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A Case of Feline Infectious Peritonitis with Intestinal Manifestation in a Cat
Hyun-jung Oh, Jung-min Sohn, Sun-young Jung, Bo-eun Kim,
Seo-yeoun JI, Joo-hyun Jung*, Dae-yong Kim, Hwa-young Youn, Junghee Yoon and Min-cheol Choi1 College of Veterinary Medicine and the Research Institute for Veterinary Science, Seoul National University, Seoul 151-742, Korea
*Ilsan Animal Medical Center, Daehwa-dong 2030, Ilsanseo-gu, Goyang-si, Gyeonggi-do 411-803, Korea (Accepted: October 13, 2014)
Abstract : A 2-year-old, intact male, Persian exotic cat, weighing 2 kg with a history of a palpated abdominal mass was admitted to Veterinary Medical Teaching Hospital, Seoul National University. On routine complete blood count (CBC) and serum biochemical analyses, there were anemia and 0.45 of albumin to globulin ratio. A feline infectious peritonitis (FIP) virus antibody test kit was negative. Radiography, ultrasonography and computed tomography (CT) were performed. A markedly enlarged abdominal mass was found. On cytologic examination of this mass, it was diagnosed as alimentary lymphoma or pyogranulomatous inflammation. Chemotherapeutic treatment for intestinal lymphoma was provided for several weeks, but the mass size was increased and clinical signs were not improved.
The cat died six days after discontinuing chemotherapy. On postmortem examination, the definitive diagnosis was FIP.
This case describes a cat with FIP in which an abdominal tumor had been suspected clinically.
Key words : FIP, abdominal mass, CT, non-effusive, effusive.
Introduction
The feline infectious peritonitis virus (FIPV) is a virulence form of feline enteric coronavirus (FECV) that can present with a variety of clinical signs which characterized by fever, anorexia, depression and ascites (7,12,13,14,17). On some occasions granulomatous masses can be palpated in the mesentery or may be associated with visceral organs (2). The most noticeable characteristics are diffuse fibrinous peritoni- tis, mesothelial hyperplasia and focal necrosis in parenchyma- tous organs on postmortem examination. The body cavities also may contain varying quantities of viscid exudate.
According to the amount of exudated fluid into the body cav- ities, feline infectious peritonitis (FIP) can be divided with two forms, effusive and non-effusive. Assorted clinicopatho- logical features suggestive of FIPV infection have been examined, with variable diagnostic utility (3,7). At presents, histopathological or postmortem examination remains the only test to definitively diagnose FIP (7,18). Although none of definite diagnostic tests for FIPV infection, combination of history, physical examination, and competent choice of diagnostic tests should increase the index of suggestion for FIPV infection when considered along with relevant clinical signs. This case shows that natural FIP can be dominated by, or restricted to, a massive thickening of the small intestine, leading to the clinical suspicion of an abdominal neoplasm.
The purpose of this case is to characterize FIP presenting as a tumor in the abdominal cavity and to help strengthen ante- mortem diagnosis and not exclude the possibility of FIPV
infection.
Case
A 2-year-old, intact male, Persian exotic cat, weighing 2 kg was referred to Veterinary Medical Teaching Hospital, Seoul National University with a history of a palpated abdominal mass, anorexia, vomiting and increased daytime sleepiness.
Physical examination revealed a body condition score of 2/9, 6% dehydration, mildly increased abdominal pressure and a solid mass in abdominal cavity at just caudal costal arch of right side when palpating the abdomen.
A blood sample from the jugular vein was taken for rou- tine CBC and serum biochemical analyses. The results were PCV 21.4% (reference range; 27.7-46.8%), which repre- sented anemia, mildly decreased BUN (8.8 mg/, reference range; 15-34 mg/), creatinine (0.91 mg/, reference range; 1.0- 2.2 mg) and slight elevation of glucose (132 mg/, reference range; 60-130 mg/). Albumin was low margin of normal range and an albumin to globulin ratio was 0.45 (albumin 2.4 g/dl, Total protein 7.71 g/dl). Both a FIP virus antibody test kit and feline leukemia virus antigen-feline immunodefi- ciency virus antibody test kit were negative.
On abdominal radiographs, mild hepatomegaly and dif- fuse, mild loss of serosal detail, especially in the cranial abdomen, were identified (Fig 1). The abdominal ultrasonog- raphy revealed an oval-shaped, hypoechoic, heterogeneous mass in the cranial to mid-abdomen and medial to the right liver lobe (Fig 2A). This mass which was attached to the jejunal segments contained necrolytic and hemorrhagic lesion with mineralization, and tortuous course of the intestinal loops were adjacent to the mass (Fig 2B). Several large blood vessels were across the mass with severe blood signal (Fig
1Corresponding author.
E-mail: [email protected]
2C). There were a small amount of anechoic free fluid and increased echogenicity in the mesenteric fat around the mass (Fig 2D). As free fluid was insufficient, abdominocentesis
was not conducted.
To determine the origin of the mass, CT (computed tomog- raphy) was performed. Enhanced CT with 3 ml/kg of con- Fig 1. Abdominal radiographs, lateral (A) and ventrodorsal (B) view. Mild-diffuse loss of serosal detail is observed on both projections.
Especially in the cranial abdomen (arrow), this loss is more prominent.
Fig 2. Abdominal ultrasonographs of the mass in the cranial to mid-abdomen. (A), A solitary abdominal mass has oval shape and inho- mogenous, hypoechoic parenchymal echogenicity. (size: L× W × H = 4.06 × 2.98 × 2.88 cm) (B), Color Doppler shows several large blood vessels across the mass with severe blood signal. (C), Tortuous course of intestinal loops adjacent to the mass is shown. (D), Also, there is a small amount of anechoic free fluid around the mass.
trast agent (Omnipaque®, Cork, Ireland) intravenously followed by plain scan (3 mm slice thickness, pitch 1.5) showed a markedly enlarged mass, which may be arise from the small intestine, with heterogeneous contrast enhancement and adja- cent to the superior mesenteric vein in the caudal region of the right kidney with left displacement of the duodenum (Fig 3A). This superior mesenteric vein had irregular and indis- tinct margin, so possibly adhered to the mass (Fig 3C). The adjacent jejunal lymph node was indistinct and the pancreat- icoduodenal lymph node was mildly enlarged, which also possibly were malignant infiltration or inflammatory change (Fig 3B). Moderate to severe splenomegaly and a nodule with contrast enhancement in the splenic parenchyma was observed (Fig 3C).
Cytological analysis of fine needle aspirates from the splenic parenchyma and abdominal mass was performed. The result of the abdominal mass was suspected to intestinal lym- phoma or pyogranulomatous inflammation. However, the diagnostic value in splenic sample was not found.
Depending on the results of cytologic examination, the cat was respected to alimentary lymphoma and conducted che- motherapy for lymphoma. But as a result of deterioration of clinical signs, hematological results and imaging findings, the chemotherapy was discontinued. At six days after stop-
ping chemotherapy, this cat was expired.
On postmortem examination, the definitive diagnosis was FIP characterized by severe chronic-active multifocal to coa- lescing pyogranulomatous inflammatory lesions confined to the mesentery and intestine with a small amount of ascites.
Discussion
FIP has been presented the typical physical and historical findings and numerous distinguishing laboratory, clinical, and imaging abnormalities. The earliest signs of apparent FIP involve a progressively worsening malaise, fluctuating fever, anorexia, and weight loss. Other signs of disease are super- imposed on these basic disease signs, depending on the form and organ distribution of the inflammation (2,12,19).
Previously published studies have reported that cats younger than 5 years of age, males and originating from pure breed cat- teries or shelters are more commonly affected (1,7,15).
Laboratory results in cats with FIP often revealed several abnormalities which tend to be similar regardless of the form of disease; anemia, hyperglobulinemia, lymphopenia, and feline infectious enteric coronavirus (FECV) titers > 1:1600 (3,7,11,15,16). The most constant findings in cats with FIP are elevated globulin and decreased albumin : globulin (A : G ratio). The elevation of the serum total proteins is associ- ated with increased level of globulin and decreased level of albumin. An albumin / globulin ratio < 0.6 is considered diag- nostic for an inflammatory process, and most commonly FIP (5,12).
This case seems consistent with age, breed and sex with other previously published studies indicating that young (< 5 years old), purebred, male cats are most commonly affected.
Additionally, this cat presented with previously mentioned clinical signs such as anorexia, weight loss, vomiting and biochemistry and hematological abnormalities suggesting of FIP infection.
So the diagnosis of FIP may be relatively simple, given its affinity for younger cats, its strong tendency to involve cat- teries and shelters, the typical physical and historical find- ings and numerous characteristic laboratory abnormalities.
Nonetheless, it somehow remains one of the most difficult Fig 3. The contrast enhanced and reformatted CT images of the
abdomen. (A), Transverse CT image. A markedly enlarged mass with heterogenous contrast enhancement (asterisk) is identified.
The mass is in the caudal region of the right kidney and the duodenum is displaced to the left side by the mass (arrow). (B), Coronal CT image. A strong contrast-enhanced pancreati- coduodenal lymph node (arrow head) and enlarged spleen (small hollow arrow) are shown. The mass (asterisk) is in the right mid-abdomen. The enhanced mass may invade into the pancre- aticoduodenal lymph node and spleen. (C), Coronal and trans- verse CT image. This superior mesenteric vein (short arrow) has irregular and indistinct margin, so possibly adhered to the mass.
Also a nodule with contrast enhancement in the splenic paren- chyma is observed (small hollow arrow).
Fig 4. Microscopic appearance of the suspected lymphoma lesion.
The severe chronic-active multifocal to coalescing pyogranulo- matous inflammatory lesions are confined to the mesentery and intestine.
decrease in serosal detail in the cranial to mid-abdomen. The abdominal ultrasonography in this region showed an oval shaped mass with little anechoic free fluid. It is difficult to examine peritoneal fluid because of insufficient amount. The characteristics and invasive range of the mass were detected more specifically by CT scan. But we couldn't diagnose FIP infection based on imaging diagnostic test alone. In a cyto- logical test of the mass, the results represented intestinal lym- phoma and granulomatous inflammation depending on aspirating sites of the mass.
In our case, this cat was tentatively diagnosed with alimen- tary lymphoma. However the definitive diagnosis was FIP with pyogranulomatous inflammatory lesions, not lymphoma on the postmortem examination. Our case had a mass in abdominal cavity with a small amount of ascites at first time.
The dry form has been less recognized and reported than wet form. Also, FIP with a solitary mass is not common. A soli- tary intestinal mass has previously been reported in 17% of FIP cases diagnosed histologically (4,7). These made it more difficult to diagnose the non-effusive form of FIP.
Many previous studies state that the lesion like a mass of dry FIP have been mistaken for cancer, in particular lym- phoma (6,9,12). Differential diagnoses of a solitary mass in the abdominal cavity associated with FIP infection include abdominal lymphadenopathy and lymphoma depending on the involvement of abdominal parenchymatous organs, espe- cially the kidneys, bowel wall and liver (6,7,9,10,12). Biopsy of visible lesions as well as surrounding organs, and postmor- tem examination are needed for definite diagnose of the mass.
FIP has usually been divided with effusive and non-effu- sive form (8,9). The effusive (wet, non-parenchymatous) FIP is the most common form, which is a transmissible inflam- matory condition of the visceral serosa and omentum with exudation into the abdomen (19). The non-effusive (dry, par- enchymatous) form is characterized by granulomatous or pyogranulomatous involvement of parenchymatous organs, especially the kidneys, mesenteric lymph nodes, bowel wall, liver, brain and eyes (10,12). However no strict distinction between the effusive and non-effusive can be made.
Non-effusive FIP may become effusive form in the termi- nal stages of the disease, when the immune system col- lapses. If humoral immunity occurs, but cellular immunity fails to develop, the resulting disease is effusive or wet (12).
In this case, the cat had little peritoneal fluid like dry form of FIP at first. After tentative diagnosis of lymphoma, the amount of peritoneal fluid increased during chemotherapeutic treat- ment. Also we can find features of wet form such as yellow-
describes minutely FIP with a mass confined to intestine and mesentery, so it helps to strengthen antemortem diagnosis.
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고양이에서 장 병변을 가진 고양이 전염성 복막염 감염 증례
오현정·손정민·정선영·김보은·지서연·정주현*·김대용·윤화영·윤정희·최민철1
서울대학교 수의과대학, *일산동물의료원
요 약 : 복강 내 종괴 촉진 및 구토, 식욕부진, 발열, 체중 감소, 수면시간 증가를 보이는 한 마리의 고양이가 서울대 학교 부속 동물병원에 내원하였다. 신체검사, 혈액검사와 더불어 영상학적 검사가 진행되었다. 복부 초음파, CT 검사 를 통해 소장분절과 연결된 종괴가 확인되었으며, 종괴에 대한 세포학적 검사 결과 소화기 림프종으로 잠정 진단되었 으며 이에 따른 항암치료가 이뤄졌다. 항암치료가 진행되는 동안 증상은 호전되지 않았고, 결국 항암치료 중단 6일 후 폐사하였다. 부검이 이뤄졌으며 최종적으로 병변은 조직병리학적 검사를 통해 고양이 전염성 복막염으로 확진하였다.
주요어 : 고양이 전염성 복막염, 복강 종괴, 컴퓨터 단층촬영, 비삼출성, 삼출성
