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J Vet Clin 2022; 39(3): 138-143

https://doi.org/10.17555/jvc.2022.39.3.138

Published online June 30, 2022

Intestinal Lymphoma in a Halla Horse

Hyohoon Jeong , Seyoung Lee , Kyung-won Park , Eun-bee Lee , Jae-Hoon Kim , Ji-Youl Jung , Jong-pil Seo

College of Veterinary Medicine, Jeju National University, Jeju 63243, Korea

Correspondence to:*jpseo@jejunu.ac.kr

Received: March 1, 2022; Revised: April 14, 2022; Accepted: April 25, 2022

Copyright © The Korean Society of Veterinary Clinics.

A 21-year-old female Halla Horse weighing 248 kg was referred to the Jeju National University Equine Hospital with the chief complaint of anorexia accompanied by general weakness and depression for the previous three days suspected to be related to colic. Extensive diagnostic tests were performed for the following six days, including complete blood count (CBC), serum chemistry, gastroscopy, x-rays, and ultrasound imaging. The signalment, history, symptoms, and test results strongly suggested a chronic intestinal inflammatory disease with or without an alimentary tumor; hence, an exploratory laparotomy was performed. Almost the entire small intestine wall was severely thickened with diffuse ecchymosis on the serosa and protruded nodules on the mucosa. A presumptive diagnosis of an intestinal tumor was made, and the patient was euthanized, considering the patient’s welfare with poor prognosis and low expectancy. A massive part of the small intestine was collected and submitted for macroscopic and microscopic pathology evaluations. The pathologic examination, including immunohistochemistry (IHC), indicated equine intestinal lymphoma showing strong positivity for T cell marker. This report describes the clinical signs, diagnosis and pathological features of intestinal lymphoma in a Halla Horse in detail.

Keywords: intestinal lymphoma, immunohistochemistry, T cell, Halla horse.

Lymphoma or malignant lymphoma, also known as lymphosarcoma, is a haematopoietic neoplasia of the lymphoid tissue, including the lymph nodes, spleen, and gut-associated lymphoid tissue (8). The intestinal form of lymphoma is the most commonly observed equine intestinal tumor, but equine intestinal neoplasia is rare (3,9). The overall occurrence of lymphoma is approximately 1.3-2.8% of all equine tumors, with a prevalence of 0.002-0.05% of the horse population (5,6). Classification of equine lymphoma is as follows based on the anatomic distribution: multicentric or generalized, alimentary, mediastinal, cutaneous and solitary tumors of the extranodal sites (6,8). The common clinical signs of equine lymphoma include decreased appetite, depression, weight loss, fever, lymphadenopathy and dependent edema (6). A diagnosis of lymphoma is often difficult because of the insidious and atypical clinical signs. The initial diagnostic investigation of a patient with suspected lymphoma should include a physical examination, palpation of the accessible abdominal organs per rectum, complete blood count (CBC), and serum biochemistries, as well as an ultrasonographic examination to locate a mass and the extent of organ or lymph node affected (6,9). However, the definitive diagnosis of lymphoma requires the observation of neoplastic cells in the aspirates or biopsy specimens of lymph nodes and other masses (2,6,8). Although the intestinal forms of equine lymphoma can develop in horses raised in the Republic of Korea based on the history of the patients and their clinical signs, reports on the diagnostic efforts regarding this condition are extremely rare among horse owners and clinicians due to the lack of therapeutic options, poor prognosis and the cost for the diagnosis. This report describes a case of equine intestinal lymphoma including the clinical features and diagnostic procedures in detail.

A 21-year-old female Halla Horse weighing 248 kg was referred to the Jeju National University Equine Hospital with the clinical signs of anorexia accompanied by general weakness, depression, frequent stretching, and teeth grinding over the previous three days before referral. The case was suspected of colic, as stated by the owner (Fig. 1). At admission, the patient was depressed and showed decreased appetite. The body condition score of the patient was 4 to 5 out of 9 at the presentation, which was normal. The body temperature, respiratory rate, and heart rate were 36.9°C, 20 times/min, and 66 beats/min, respectively. The color of the mucous membrane was pale pink and the capillary refill time was normal within 1.5 seconds. Thoracic auscultation did not show any abnormal signs. The abdominal auscultation indicated decreased gut motility. The CBC results indicated leukopenia with lymphopenia (Table 1). The serum chemistry results revealed an increased bilirubin level (Table 2). Gastroscopy was conducted to exclude the anorexia caused by gastric ulcers, which confirmed that there were no signs of ulceration (Fig. 2). There were no specific findings at rectal palpation either. The abdominal ultrasound examination revealed diffuse small intestinal wall thickening with edema indicating the presence of small intestinal inflammation (Fig. 3). The patient was hospitalized to be given empirical treatment for colic with small intestinal inflammation and pursued further examinations. Fluid therapy with the Lactated Ringer Solution supplemented with 5% dextrose was initiated with an antibiotic (PPS; Daesung) at 0.05 mL/kg intramuscularly, consisting of 5,000 IU/kg of penicillin G benzathine hydrate, 7,500 IU/kg of penicillin G procaine, and 10 mg/kg of dihydrostreptomycin sulfate, SID along with an NSAID, flunixin meglumine (Fortis; Dongbang) at 1.1 mg/kg intravenously BID. The body temperature of the patient went up to 38.7°C on that night regardless of repeated flunixin meglumine administration. The following morning, the body temperature dropped to 37.5°C, and the patient was taken the chest and abdominal x-rays, which revealed no specific findings. The evening of the 2nd day of hospitalization, the body temperature went up to 39.9°C, so gentamicin (Gentamicin; Daesung) at 5.0 mg/kg intravenously BID was added to the existing protocol starting from the 3rd day of hospitalization. The CBC performed on day 3 showed that the leukopenia had deteriorated (Table 1) with remittent fever regardless of the continuous antibiotics, NSAID, and fluid therapy. The patient was continued on the same treatment regimen for the following four days, but there was no clinical improvement observed. Overall, the signalment, history, symptoms, and test results strongly suggested a chronic gastrointestinal inflammatory disease with or without an alimentary tumor. Consequently, an exploratory laparotomy was performed under inhalation anesthesia with appropriate fluid therapy on day seven. The patient was given an antibiotic (PPS; Daesung) along with an NSAID, flunixin meglumine (Fortis; Dongbang) preoperatively. The patient was premedicated with 10 μg/kg of detomidine (Provet Detomidin; Provet), 10 μg/kg of diazepam (Diazepam; Samjin) and 10 μg/kg of butorphanol tartrate (Butorphan; Myungmoon). Anesthesia was induced with 1.1 mg/kg of ketamine (Ketamin; Yuhan), then was maintained with isoflurane (Ifrane; Hana). The patient was placed in dorsal recumbency. The abdominal region was prepared aseptically. A sterile urinary catheter was placed in the urethra. The skin incision was made using a No. 20 scalpel blade. Upon opening the abdominal wall, the peritoneal cavity and the organs were examined carefully. The entire wall of the small intestine was thickened with edema when palpated. Diffuse ecchymosis was observed on the omentum and the serosa of the small intestine (Fig. 4A). The mucosa of the small intestine was thickened with protruded nodules (Fig. 4B). A presumptive diagnosis of an intestinal tumor was established. The patient was euthanized upon the owner’s request for the sake of the patient’s welfare with a poor prognosis. A massive part of the small intestine was collected and submitted for macroscopic and microscopic pathology evaluations including immunohistochemistry (IHC). Pathologically, abdominal neoplastic round cells were diffusely infiltrated from the mucosa to the serosa of the intestine (Fig. 5A, B). These neoplastic cells were large sized with hyperchromatic nuclei and moderate cytoplasms (Fig. 5C). Immunohistochemically, these cells showed strong positive reactions for CD3, a T cell marker (Fig. 5D).

Table 1 CBC results of the patient while hospitalized

ParameterNormal valuesDay 1Day 3Day 4Day 7
PCV (%)24-5345.9243.8545.4046.81
Hb (g/dL)8-1914.414.515.115.4
Leukocytes (103/µL)5.4-14.34.203.856.826.22
Neutrophils (103/µL)2.3-9.63.082.895.625.40
Lymphocytes (103/µL)1.5-7.70.940.820.870.55
Monocytes (103/µL)0-1.20.140.090.270.24
Platelets (103/µL)90-350153186193214


Table 2 Biochemical parameters at the initial presentation

ParameterNormal rangeValue
Na+ (mmol/L)126-146133
K+ (mmol/L)2.5-5.23.9
TCO2 (mmol/L)20-3318
CK (IU/L)120-470333
Glu (mg/dL)65-110117
Ca2+ (mg/dL)11.5-14.211.4
BUN (mg/dL)7-2519
Cre (mg/dL)0.6-2.21.4
AST (IU/L)175-340224
TBIL (mg/dL)0.5-2.35.1
GGT (IU/L)5-2411
Albumin (g/dL)2.2-3.73.1
TP (g/dL)5.7-8.07.4
Glob (g/dL)2.7-5.04.3


Figure 1.The patient is showing frequent stretching owing to the abdominal pain with the forelimbs and hindlimbs extended.

Figure 2.Gastroscopic images of the patient. Please note that there was no sign of ulceration. (A) Distal part of the esophagus (B) Squamous fundus of the stomach.

Figure 3.Transcutaneous abdominal ultrasound image (2 MHz frequency probe) of the small intestine. There is marked small intestinal wall thickening in the luminal surface with edema indicated by a white arrowhead. The serosal surface is indicated by white solid arrows.

Figure 4.(A) Multifocal ecchymosis on the serous membrane of the small intestine and the omentum. (B) Diffuse thickening of the wall and various protruded nodules on the mucosa of the small intestine.

Figure 5.(A) Neoplastic lymphocytes are infiltrated in the mucosa and submucosa of the small intestine. H&E, Bar = 100 um. (B) Neoplastic lymphocytes are observed in the muscle layer and serosa of the small intestine. H&E, Bar = 200 um. (C) Lymphoid neoplastic cells are large sized and round shaped, with hyperchromatic nuclei and moderate cytoplasms. Mitotic index (arrows). H&E, Bar = 20 um. (D) The neoplastic cells showed strong positivity for CD3, a T cell marker. IHC. Bar = 50 um.

It is often challenging to differentiate alimentary tumor from inflammatory bowel disease, nonbowel, intra-abdominal tumor and peritoneal abscess because patient history, clinical symptoms and diagnostic results can be atypical and similar (9). Although a diverse spectrum of clinical signs may be associated with lymphoma, the most commonly seen clinical symptoms include anorexia, depression, weight loss, fever, lymphadenopathy, abdominal distension, diarrhea, and edema (2,6,9). The chief complaint of the present case was decreased appetite with some similar clinical signs to colic, including abdominal pain and decreased gut motility. The stretching related to the abdominal pain and anorexia did not improve with the conventional pain- relieving therapy on top of the fluid therapy. The related general weakness and depression were not showing signs of improvement while hospitalized. Hence, an exploratory laparotomy was performed for a definite diagnosis. The remittent fever also suggested the possibility of chronic inflammatory bowel disease with or without an intestinal tumor for the present case. The leukopenia which appeared to have been corrected with antibiotic therapy, could also have been caused by the inflammation and erosion of the neoplastic lesions of the small intestine. The atypical and various clinical signs thought to be related to colic, especially in aged patients, should be considered for the possibility of an intestinal tumor by the clinicians as seen in this case as it has been reported that the lymphoma tends to occur in aged horses (mean age 16 years old) (9).

A diagnosis of lymphoma could be difficult, antemortem confirmation is made in less than 60% of cases (6,9). The possibility of tumors always has to be considered in horses with recurrent inflammatory and febrile episodes that are unresponsive to antimicrobial therapy, as with the present case, because there are no risk factors for equine lymphoma established yet (6). The initial diagnostic procedure for intestinal lymphoma should include a physical examination, rectal palpation of accessible organs, CBC, and serum biochemistries (8). Ultrasound imaging of the thorax and abdomen maybe helpful for locating a mass and the extent of the organ or localized lymph node involvement (5,9). However, the definitive diagnosis of lymphoma can be established through observation of neoplastic cells in the aspirates or biopsy specimens of lymph nodes, other masses, or in centesis samples of the body cavity fluids, bone marrow aspirates, or peripheral blood (2,6,9). Various diagnostic efforts were made for the present case, which included a thorough general physical examination, rectal examination, CBC and chemistries, gastroscopy, chest and abdominal x-rays and ultrasound imaging. Although each piece of information provided valuable clues for a presumptive diagnosis of chronic inflammatory bowel disease with or without an intestinal tumor, ultrasound imaging was the most useful diagnostic tool to assist in diagnosing intestinal tumor, as stated above and elsewhere (7,9). The wall of the small intestine consisted of five wall layers of the mucosal interface, mucosa, submucosa, muscularis, and serosa. Nevertheless, they are not readily visible on ultrasound imaging when it is 2-3 mm thick, but deviations from the normal wall structure, wall thickening with changes in echogenicity may be observed by sonogram (1,7). For the present case, obtaining better quality ultrasound images was challenging because of the nature of the thick hair coat and abundant sebum of the Halla Horse, even though the image quality was sufficient to provide a presumptive diagnosis of inflammatory bowel disease as the small intestinal thickening is most prominent in horses with lymphoma (4,9). The following steps left for a definite diagnosis to be established were a laparotomy and macro and microscopic pathology examination including IHC to determine immunophenotype. The laparotomy confirmed the presence of a tumor, and IHC allowed a definite diagnosis of equine intestinal lymphoma showing strong positivity for CD3 T cell marker in this case.

The treatment option for equine lymphoma is comparable to that of small animals, but there is little information on the treatment response for equine lymphoma is sparse since the majority of the cases are diagnosed postmortem or remain undiagnosed until the end-stage, as seen in this case (6,8). Considering the age of the patient, the extent of the lesion, and the clinical signs of pain, the owner selected euthanasia for the sake of the patient. Further diagnostic and clinical trials regarding equine lymphoma on a vast scale will be needed to provide the patient and the owners with a more accurate diagnosis, various and inexpensive therapeutic options, and information regarding prognosis.

A 21-year-old female Halla Horse was diagnosed with intestinal lymphoma based on the clinical signs, the results of various diagnostic evaluations, exploratory laparotomy, and pathology examination, including IHC. Descriptions of the clinical signs and diagnosis regarding equine intestinal lymphoma are rare among horse owners and clinicians owing to the low incidence of occurrence and difficulty for antemortem diagnosis, as well as the high mortality of the patients with the condition in the Republic of Korea. The authors expect clinicians to find this report beneficial when dealing with challenging clinical cases with various atypical clinical signs of chronic weight loss, recurrent colic, and decreased performance in aged horses.

The authors have no conflicting interests.

  1. Dechant JE, Whitcomb MB, Magdesian KG. Ultrasonographic diagnosis-Idiopathic muscular hypertrophy of the small intestine in a miniature horse. Vet Radiol Ultrasound 2008; 49: 300-302.
    Pubmed CrossRef
  2. Duran MC, Starrak G, Dickinson R, Montgomery J. Peritoneal fluid immunocytochemistry used for the diagnosis of a possible case of equine gastrointestinal B-cell lymphoma. Can Vet J 2016; 57: 601-604.
  3. Durham AC, Pillitteri CA, San Myint M, Valli VE. Two hundred three cases of equine lymphoma classified according to the World Health Organization (WHO) classification criteria. Vet Pathol 2013; 50: 86-93.
    Pubmed CrossRef
  4. Miglio A, Morelli C, Gialletti R, Lauteri E, Sforna M, Marenzoni ML, et al. Clinical and immunophenotypic findings in 4 forms of equine lymphoma. Can Vet J 2019; 60: 33-40.
  5. Savage CJ. Lymphoproliferative and myeloproliferative disorders. Vet Clin North Am Equine Pract 1998; 14: 563-578.
    CrossRef
  6. Schneider DA. Lymphoproliferative and myeloproliferative disorders. In: Robinson NE, editor. Current therapy in equine medicine. 5th ed. St. Louis: Saunders. 2003: 359-362.
    Pubmed CrossRef
  7. Sherlock C, Dawson L, Mair T. Ultrasound as a diagnostic tool in the investigation of a pony with intestinal lymphoma. Equine Vet Educ 2017; 29: 78-81.
    CrossRef
  8. Taintor J, Schleis S. Equine lymphoma. Equine Vet Educ 2011; 23: 205-213.
    CrossRef
  9. Taylor SD, Pusterla N, Vaughan B, Whitcomb MB, Wilson WD. Intestinal neoplasia in horses. J Vet Intern Med 2006; 20: 1429-1436.
    Pubmed CrossRef

Article

Case Report

J Vet Clin 2022; 39(3): 138-143

Published online June 30, 2022 https://doi.org/10.17555/jvc.2022.39.3.138

Copyright © The Korean Society of Veterinary Clinics.

Intestinal Lymphoma in a Halla Horse

Hyohoon Jeong , Seyoung Lee , Kyung-won Park , Eun-bee Lee , Jae-Hoon Kim , Ji-Youl Jung , Jong-pil Seo

College of Veterinary Medicine, Jeju National University, Jeju 63243, Korea

Correspondence to:*jpseo@jejunu.ac.kr

Received: March 1, 2022; Revised: April 14, 2022; Accepted: April 25, 2022

This is an open access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

A 21-year-old female Halla Horse weighing 248 kg was referred to the Jeju National University Equine Hospital with the chief complaint of anorexia accompanied by general weakness and depression for the previous three days suspected to be related to colic. Extensive diagnostic tests were performed for the following six days, including complete blood count (CBC), serum chemistry, gastroscopy, x-rays, and ultrasound imaging. The signalment, history, symptoms, and test results strongly suggested a chronic intestinal inflammatory disease with or without an alimentary tumor; hence, an exploratory laparotomy was performed. Almost the entire small intestine wall was severely thickened with diffuse ecchymosis on the serosa and protruded nodules on the mucosa. A presumptive diagnosis of an intestinal tumor was made, and the patient was euthanized, considering the patient’s welfare with poor prognosis and low expectancy. A massive part of the small intestine was collected and submitted for macroscopic and microscopic pathology evaluations. The pathologic examination, including immunohistochemistry (IHC), indicated equine intestinal lymphoma showing strong positivity for T cell marker. This report describes the clinical signs, diagnosis and pathological features of intestinal lymphoma in a Halla Horse in detail.

Keywords: intestinal lymphoma, immunohistochemistry, T cell, Halla horse.

Introduction

Lymphoma or malignant lymphoma, also known as lymphosarcoma, is a haematopoietic neoplasia of the lymphoid tissue, including the lymph nodes, spleen, and gut-associated lymphoid tissue (8). The intestinal form of lymphoma is the most commonly observed equine intestinal tumor, but equine intestinal neoplasia is rare (3,9). The overall occurrence of lymphoma is approximately 1.3-2.8% of all equine tumors, with a prevalence of 0.002-0.05% of the horse population (5,6). Classification of equine lymphoma is as follows based on the anatomic distribution: multicentric or generalized, alimentary, mediastinal, cutaneous and solitary tumors of the extranodal sites (6,8). The common clinical signs of equine lymphoma include decreased appetite, depression, weight loss, fever, lymphadenopathy and dependent edema (6). A diagnosis of lymphoma is often difficult because of the insidious and atypical clinical signs. The initial diagnostic investigation of a patient with suspected lymphoma should include a physical examination, palpation of the accessible abdominal organs per rectum, complete blood count (CBC), and serum biochemistries, as well as an ultrasonographic examination to locate a mass and the extent of organ or lymph node affected (6,9). However, the definitive diagnosis of lymphoma requires the observation of neoplastic cells in the aspirates or biopsy specimens of lymph nodes and other masses (2,6,8). Although the intestinal forms of equine lymphoma can develop in horses raised in the Republic of Korea based on the history of the patients and their clinical signs, reports on the diagnostic efforts regarding this condition are extremely rare among horse owners and clinicians due to the lack of therapeutic options, poor prognosis and the cost for the diagnosis. This report describes a case of equine intestinal lymphoma including the clinical features and diagnostic procedures in detail.

Case Report

A 21-year-old female Halla Horse weighing 248 kg was referred to the Jeju National University Equine Hospital with the clinical signs of anorexia accompanied by general weakness, depression, frequent stretching, and teeth grinding over the previous three days before referral. The case was suspected of colic, as stated by the owner (Fig. 1). At admission, the patient was depressed and showed decreased appetite. The body condition score of the patient was 4 to 5 out of 9 at the presentation, which was normal. The body temperature, respiratory rate, and heart rate were 36.9°C, 20 times/min, and 66 beats/min, respectively. The color of the mucous membrane was pale pink and the capillary refill time was normal within 1.5 seconds. Thoracic auscultation did not show any abnormal signs. The abdominal auscultation indicated decreased gut motility. The CBC results indicated leukopenia with lymphopenia (Table 1). The serum chemistry results revealed an increased bilirubin level (Table 2). Gastroscopy was conducted to exclude the anorexia caused by gastric ulcers, which confirmed that there were no signs of ulceration (Fig. 2). There were no specific findings at rectal palpation either. The abdominal ultrasound examination revealed diffuse small intestinal wall thickening with edema indicating the presence of small intestinal inflammation (Fig. 3). The patient was hospitalized to be given empirical treatment for colic with small intestinal inflammation and pursued further examinations. Fluid therapy with the Lactated Ringer Solution supplemented with 5% dextrose was initiated with an antibiotic (PPS; Daesung) at 0.05 mL/kg intramuscularly, consisting of 5,000 IU/kg of penicillin G benzathine hydrate, 7,500 IU/kg of penicillin G procaine, and 10 mg/kg of dihydrostreptomycin sulfate, SID along with an NSAID, flunixin meglumine (Fortis; Dongbang) at 1.1 mg/kg intravenously BID. The body temperature of the patient went up to 38.7°C on that night regardless of repeated flunixin meglumine administration. The following morning, the body temperature dropped to 37.5°C, and the patient was taken the chest and abdominal x-rays, which revealed no specific findings. The evening of the 2nd day of hospitalization, the body temperature went up to 39.9°C, so gentamicin (Gentamicin; Daesung) at 5.0 mg/kg intravenously BID was added to the existing protocol starting from the 3rd day of hospitalization. The CBC performed on day 3 showed that the leukopenia had deteriorated (Table 1) with remittent fever regardless of the continuous antibiotics, NSAID, and fluid therapy. The patient was continued on the same treatment regimen for the following four days, but there was no clinical improvement observed. Overall, the signalment, history, symptoms, and test results strongly suggested a chronic gastrointestinal inflammatory disease with or without an alimentary tumor. Consequently, an exploratory laparotomy was performed under inhalation anesthesia with appropriate fluid therapy on day seven. The patient was given an antibiotic (PPS; Daesung) along with an NSAID, flunixin meglumine (Fortis; Dongbang) preoperatively. The patient was premedicated with 10 μg/kg of detomidine (Provet Detomidin; Provet), 10 μg/kg of diazepam (Diazepam; Samjin) and 10 μg/kg of butorphanol tartrate (Butorphan; Myungmoon). Anesthesia was induced with 1.1 mg/kg of ketamine (Ketamin; Yuhan), then was maintained with isoflurane (Ifrane; Hana). The patient was placed in dorsal recumbency. The abdominal region was prepared aseptically. A sterile urinary catheter was placed in the urethra. The skin incision was made using a No. 20 scalpel blade. Upon opening the abdominal wall, the peritoneal cavity and the organs were examined carefully. The entire wall of the small intestine was thickened with edema when palpated. Diffuse ecchymosis was observed on the omentum and the serosa of the small intestine (Fig. 4A). The mucosa of the small intestine was thickened with protruded nodules (Fig. 4B). A presumptive diagnosis of an intestinal tumor was established. The patient was euthanized upon the owner’s request for the sake of the patient’s welfare with a poor prognosis. A massive part of the small intestine was collected and submitted for macroscopic and microscopic pathology evaluations including immunohistochemistry (IHC). Pathologically, abdominal neoplastic round cells were diffusely infiltrated from the mucosa to the serosa of the intestine (Fig. 5A, B). These neoplastic cells were large sized with hyperchromatic nuclei and moderate cytoplasms (Fig. 5C). Immunohistochemically, these cells showed strong positive reactions for CD3, a T cell marker (Fig. 5D).

Table 1 . CBC results of the patient while hospitalized.

ParameterNormal valuesDay 1Day 3Day 4Day 7
PCV (%)24-5345.9243.8545.4046.81
Hb (g/dL)8-1914.414.515.115.4
Leukocytes (103/µL)5.4-14.34.203.856.826.22
Neutrophils (103/µL)2.3-9.63.082.895.625.40
Lymphocytes (103/µL)1.5-7.70.940.820.870.55
Monocytes (103/µL)0-1.20.140.090.270.24
Platelets (103/µL)90-350153186193214


Table 2 . Biochemical parameters at the initial presentation.

ParameterNormal rangeValue
Na+ (mmol/L)126-146133
K+ (mmol/L)2.5-5.23.9
TCO2 (mmol/L)20-3318
CK (IU/L)120-470333
Glu (mg/dL)65-110117
Ca2+ (mg/dL)11.5-14.211.4
BUN (mg/dL)7-2519
Cre (mg/dL)0.6-2.21.4
AST (IU/L)175-340224
TBIL (mg/dL)0.5-2.35.1
GGT (IU/L)5-2411
Albumin (g/dL)2.2-3.73.1
TP (g/dL)5.7-8.07.4
Glob (g/dL)2.7-5.04.3


Figure 1. The patient is showing frequent stretching owing to the abdominal pain with the forelimbs and hindlimbs extended.

Figure 2. Gastroscopic images of the patient. Please note that there was no sign of ulceration. (A) Distal part of the esophagus (B) Squamous fundus of the stomach.

Figure 3. Transcutaneous abdominal ultrasound image (2 MHz frequency probe) of the small intestine. There is marked small intestinal wall thickening in the luminal surface with edema indicated by a white arrowhead. The serosal surface is indicated by white solid arrows.

Figure 4. (A) Multifocal ecchymosis on the serous membrane of the small intestine and the omentum. (B) Diffuse thickening of the wall and various protruded nodules on the mucosa of the small intestine.

Figure 5. (A) Neoplastic lymphocytes are infiltrated in the mucosa and submucosa of the small intestine. H&E, Bar = 100 um. (B) Neoplastic lymphocytes are observed in the muscle layer and serosa of the small intestine. H&E, Bar = 200 um. (C) Lymphoid neoplastic cells are large sized and round shaped, with hyperchromatic nuclei and moderate cytoplasms. Mitotic index (arrows). H&E, Bar = 20 um. (D) The neoplastic cells showed strong positivity for CD3, a T cell marker. IHC. Bar = 50 um.

Discussion

It is often challenging to differentiate alimentary tumor from inflammatory bowel disease, nonbowel, intra-abdominal tumor and peritoneal abscess because patient history, clinical symptoms and diagnostic results can be atypical and similar (9). Although a diverse spectrum of clinical signs may be associated with lymphoma, the most commonly seen clinical symptoms include anorexia, depression, weight loss, fever, lymphadenopathy, abdominal distension, diarrhea, and edema (2,6,9). The chief complaint of the present case was decreased appetite with some similar clinical signs to colic, including abdominal pain and decreased gut motility. The stretching related to the abdominal pain and anorexia did not improve with the conventional pain- relieving therapy on top of the fluid therapy. The related general weakness and depression were not showing signs of improvement while hospitalized. Hence, an exploratory laparotomy was performed for a definite diagnosis. The remittent fever also suggested the possibility of chronic inflammatory bowel disease with or without an intestinal tumor for the present case. The leukopenia which appeared to have been corrected with antibiotic therapy, could also have been caused by the inflammation and erosion of the neoplastic lesions of the small intestine. The atypical and various clinical signs thought to be related to colic, especially in aged patients, should be considered for the possibility of an intestinal tumor by the clinicians as seen in this case as it has been reported that the lymphoma tends to occur in aged horses (mean age 16 years old) (9).

A diagnosis of lymphoma could be difficult, antemortem confirmation is made in less than 60% of cases (6,9). The possibility of tumors always has to be considered in horses with recurrent inflammatory and febrile episodes that are unresponsive to antimicrobial therapy, as with the present case, because there are no risk factors for equine lymphoma established yet (6). The initial diagnostic procedure for intestinal lymphoma should include a physical examination, rectal palpation of accessible organs, CBC, and serum biochemistries (8). Ultrasound imaging of the thorax and abdomen maybe helpful for locating a mass and the extent of the organ or localized lymph node involvement (5,9). However, the definitive diagnosis of lymphoma can be established through observation of neoplastic cells in the aspirates or biopsy specimens of lymph nodes, other masses, or in centesis samples of the body cavity fluids, bone marrow aspirates, or peripheral blood (2,6,9). Various diagnostic efforts were made for the present case, which included a thorough general physical examination, rectal examination, CBC and chemistries, gastroscopy, chest and abdominal x-rays and ultrasound imaging. Although each piece of information provided valuable clues for a presumptive diagnosis of chronic inflammatory bowel disease with or without an intestinal tumor, ultrasound imaging was the most useful diagnostic tool to assist in diagnosing intestinal tumor, as stated above and elsewhere (7,9). The wall of the small intestine consisted of five wall layers of the mucosal interface, mucosa, submucosa, muscularis, and serosa. Nevertheless, they are not readily visible on ultrasound imaging when it is 2-3 mm thick, but deviations from the normal wall structure, wall thickening with changes in echogenicity may be observed by sonogram (1,7). For the present case, obtaining better quality ultrasound images was challenging because of the nature of the thick hair coat and abundant sebum of the Halla Horse, even though the image quality was sufficient to provide a presumptive diagnosis of inflammatory bowel disease as the small intestinal thickening is most prominent in horses with lymphoma (4,9). The following steps left for a definite diagnosis to be established were a laparotomy and macro and microscopic pathology examination including IHC to determine immunophenotype. The laparotomy confirmed the presence of a tumor, and IHC allowed a definite diagnosis of equine intestinal lymphoma showing strong positivity for CD3 T cell marker in this case.

The treatment option for equine lymphoma is comparable to that of small animals, but there is little information on the treatment response for equine lymphoma is sparse since the majority of the cases are diagnosed postmortem or remain undiagnosed until the end-stage, as seen in this case (6,8). Considering the age of the patient, the extent of the lesion, and the clinical signs of pain, the owner selected euthanasia for the sake of the patient. Further diagnostic and clinical trials regarding equine lymphoma on a vast scale will be needed to provide the patient and the owners with a more accurate diagnosis, various and inexpensive therapeutic options, and information regarding prognosis.

Conclusions

A 21-year-old female Halla Horse was diagnosed with intestinal lymphoma based on the clinical signs, the results of various diagnostic evaluations, exploratory laparotomy, and pathology examination, including IHC. Descriptions of the clinical signs and diagnosis regarding equine intestinal lymphoma are rare among horse owners and clinicians owing to the low incidence of occurrence and difficulty for antemortem diagnosis, as well as the high mortality of the patients with the condition in the Republic of Korea. The authors expect clinicians to find this report beneficial when dealing with challenging clinical cases with various atypical clinical signs of chronic weight loss, recurrent colic, and decreased performance in aged horses.

Conflicts of Interest

The authors have no conflicting interests.

Fig 1.

Figure 1.The patient is showing frequent stretching owing to the abdominal pain with the forelimbs and hindlimbs extended.
Journal of Veterinary Clinics 2022; 39: 138-143https://doi.org/10.17555/jvc.2022.39.3.138

Fig 2.

Figure 2.Gastroscopic images of the patient. Please note that there was no sign of ulceration. (A) Distal part of the esophagus (B) Squamous fundus of the stomach.
Journal of Veterinary Clinics 2022; 39: 138-143https://doi.org/10.17555/jvc.2022.39.3.138

Fig 3.

Figure 3.Transcutaneous abdominal ultrasound image (2 MHz frequency probe) of the small intestine. There is marked small intestinal wall thickening in the luminal surface with edema indicated by a white arrowhead. The serosal surface is indicated by white solid arrows.
Journal of Veterinary Clinics 2022; 39: 138-143https://doi.org/10.17555/jvc.2022.39.3.138

Fig 4.

Figure 4.(A) Multifocal ecchymosis on the serous membrane of the small intestine and the omentum. (B) Diffuse thickening of the wall and various protruded nodules on the mucosa of the small intestine.
Journal of Veterinary Clinics 2022; 39: 138-143https://doi.org/10.17555/jvc.2022.39.3.138

Fig 5.

Figure 5.(A) Neoplastic lymphocytes are infiltrated in the mucosa and submucosa of the small intestine. H&E, Bar = 100 um. (B) Neoplastic lymphocytes are observed in the muscle layer and serosa of the small intestine. H&E, Bar = 200 um. (C) Lymphoid neoplastic cells are large sized and round shaped, with hyperchromatic nuclei and moderate cytoplasms. Mitotic index (arrows). H&E, Bar = 20 um. (D) The neoplastic cells showed strong positivity for CD3, a T cell marker. IHC. Bar = 50 um.
Journal of Veterinary Clinics 2022; 39: 138-143https://doi.org/10.17555/jvc.2022.39.3.138

Table 1 CBC results of the patient while hospitalized

ParameterNormal valuesDay 1Day 3Day 4Day 7
PCV (%)24-5345.9243.8545.4046.81
Hb (g/dL)8-1914.414.515.115.4
Leukocytes (103/µL)5.4-14.34.203.856.826.22
Neutrophils (103/µL)2.3-9.63.082.895.625.40
Lymphocytes (103/µL)1.5-7.70.940.820.870.55
Monocytes (103/µL)0-1.20.140.090.270.24
Platelets (103/µL)90-350153186193214

Table 2 Biochemical parameters at the initial presentation

ParameterNormal rangeValue
Na+ (mmol/L)126-146133
K+ (mmol/L)2.5-5.23.9
TCO2 (mmol/L)20-3318
CK (IU/L)120-470333
Glu (mg/dL)65-110117
Ca2+ (mg/dL)11.5-14.211.4
BUN (mg/dL)7-2519
Cre (mg/dL)0.6-2.21.4
AST (IU/L)175-340224
TBIL (mg/dL)0.5-2.35.1
GGT (IU/L)5-2411
Albumin (g/dL)2.2-3.73.1
TP (g/dL)5.7-8.07.4
Glob (g/dL)2.7-5.04.3

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Vol.39 No.4 August, 2022

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The Korean Society of Veterinary Clinics

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