Lymphomatosis as a Cause of Abdominal Pain and Distension in Two Adult Horses.

Two equine patients presented separately with severe abdominal distention, colic, lethargy, and decreased appetite. An ante-mortem diagnosis of lymphoma was reached in each case based on peritoneal fluid cytology. Due to a poor prognosis, the horses were humanely euthanized. Post-mortem examination with histology and immunohistochemistry confirmed both cases as lymphoma: alimentary B-cell lymphoma of the distal jejunum and cecum in one case, and T-cell lymphoma of the cecum in the second case. Both cases exhibited extensive metastasis with peritoneal and pleural serosae covered in small nodules and plaque like masses consistent with lymphomatosis. These cases document a unique presentation of lymphoma in equine patients presenting as peritoneal lymphomatosis with ascites.

Feline sarcomatoid renal cell carcinoma with peritoneal carcinomatosis and effusion.

A 9-y-old, castrated male, domestic medium-hair cat diagnosed previously with chronic kidney disease developed anorexia and vomiting. Ultrasonography revealed abdominal effusion and a left renal perihilar mass. Cytologic evaluation of the peritoneal fluid and mass identified atypical epithelioid cells suspected to be of renal epithelial or possible mesothelial origin. Immunohistochemical (IHC) evaluation of a formalin-fixed, paraffin-embedded peritoneal fluid cell block indicated both pancytokeratin and vimentin expression in the atypical epithelioid cell population. With scanning electron microscopic evaluation, similar epithelioid cells lacked the cell-surface microvilli expected of mesothelium, supporting an antemortem diagnosis of probable carcinoma. On postmortem examination, the left kidney was effaced by an infiltrative neoplasm with myriad similar nodules throughout the peritoneum. The neoplasm was composed primarily of polygonal-to-spindle-shaped cells with strong vimentin and weak pancytokeratin cytoplasmic immunolabeling. Further IHC characterization with PAX8, CK18, KIT, napsin A, SMA, desmin, CD18, and claudin 5 was performed. Histologic and IHC findings supported a diagnosis of sarcomatoid renal cell carcinoma with peritoneal carcinomatosis. An in vitro cell culture line of neoplastic cells harvested from the primary tumor was successfully established for future research endeavors.

Concurrent Clostridial Enteritis and Oviductal Adenocarcinoma with Carcinomatosis in an Adult Alpaca (Vicugna pacos).

An adult alpaca (Vicugna pacos) with a history of colic and anorexia was euthanized because of failure to respond to treatment. Macroscopically, pale-tan, multifocal to coalescing, firm nodules and plaques markedly expanded the omentum, mesentery and the parietal and visceral peritoneum of multiple abdominal organs, especially the right oviduct and associated mesosalpinx. Abundant dark-red watery digesta were present in the duodenum and jejunum. Histological evaluation of the right oviduct, abdominal visceral nodules and plaques and mesenteric lymph nodes revealed transmural expansion and replacement by an epithelial malignant neoplasm, comprised of tubules and acini of ciliated columnar cells supported by abundant fibrous connective tissue. Both ovaries were histologically normal. On the basis of the ciliated morphology of the neoplastic cells, the focus on the proximal reproductive tract and the unremarkable ovaries, a reproductive tubal adenocarcinoma with carcinomatosis was diagnosed, with both the endometrium and oviduct considered as the tissues of origin. The prominent ciliated morphology of the neoplastic cells and the classification of human fallopian tube (oviduct) neoplasia lead us to propose oviductal adenocarcinoma with widespread carcinomatosis as the definitive diagnosis. The lamina propria of the small intestine was infiltrated segmentally by lymphocytes, plasma cells and neutrophils, and Clostridium perfringens with beta2 toxin production was identified by polymerase chain reaction in the small intestinal contents. To our knowledge, this is the first report of these two distinct diseases in an alpaca.

Clinical, CT, and ultrasonographic features of canine and feline pleural and peritoneal carcinomatosis and sarcomatosis.

Carcinomatosis and sarcomatosis describe the widespread dissemination of metastatic neoplastic cells throughout the body. Studies describing their clinical and imaging features in veterinary patients are limited. The objective of this retrospective, multicenter, cross-sectional study is to describe the clinical, ultrasonographic, and CT features of pleural and peritoneal carcinomatosis and sarcomatosis in dogs and cats to aid detection and differentiation of these lesions. Medical records and CT and ultrasonographic images were reviewed. Although a large degree of overlap was observed between the imaging features and clinical signs of canine and feline carcinomatosis and sarcomatosis, some distinguishing features were observed. Dogs were significantly more likely to present with abdominal pain compared to cats (P = .022), whereas cats more commonly presented with inappetence (P = .019). Dogs with sarcomatosis had a significantly heavier bodyweight than dogs with carcinomatosis (P = .005), largely due to a higher prevalence of splenic hemangiosarcoma in this patient cohort. Peritoneal effusion was more frequently observed in dogs with carcinomatosis compared to dogs with sarcomatosis (P = .021). Imaging and clinical features observed in this study may help to distinguish sarcomatosis and carcinomatosis lesions. Due to the large degree of overlap observed, cytological or histopathological analysis is recommended for definitive diagnosis.

Multicystic peritoneal tumor in two layer hens.

In chicken, peritoneal cystic lesions have not been clearly categorized. In this study, diffuse peritoneal multiple cysts were observed in two layer hens. The cysts in the serosa were lined with single layers of squamous or cuboidal cells. The papillary proliferations of columnar cells were also observed in one case. The smooth muscle layer or mass were observed around the cysts in both cases. The cystic lining cells were positive for pan-cytokeratin, vimentin, S100 and Wilms tumor 1. Ultrastructurally, they had sparsely microvilli on the luminal surface. The histological results indicated the present cases were multicystic mesothelioma, but also had characteristics of Mullerian epithelium. This is the first report describing the detailed pathological feature of unique multicystic tumor in chicken.

Ultrasonographic features of colonic B-cell lymphoma with mesenteric lymphomatosis in a cat.

A 10-year-old male neutered Domestic Shorthair cat was referred for chronic inappetence, weight loss, and hematochezia and an abdominal mass. Abdominal ultrasonography revealed a heterogeneously hypoechoic transmural colonic mass, which extended beyond the serosa and into the adjacent mesentery. Cytology and clonality assays of fine needle aspirates of the mass and mesenteric nodules yielded a diagnosis of B-cell lymphoma. Colonic lymphoma with mesenteric involvement can have a similar appearance to carcinomatosis, therefore a definitive diagnosis requires sampling and further testing of the mesenteric lesions.

Diagnostic efficacy of imaging and biopsy methods for peritoneal mesothelioma in a calf.

BACKGROUND: Peritoneal mesothelioma is a rare abdominal disease; that occasionally occurs congenitally in younger calves. Cytologic examination of peritoneal effusion (PE) was utilized to diagnose this disease, and was not diagnostic. Diagnostic accuracy has been elevated by recent use of ultrasonography (US), despite most diagnoses have been obtained post-mortem in slaughter houses or during clinical necropsy. In humans, ante-mortem diagnosis is highly associated with clinical use of computed tomography (CT) and laparoscopy together with imaging-assisted biopsy. The present report evaluates the diagnostic applicability of CT and laparoscopy as well as US via the practical application of these imaging modalities in an affected calf, and compares the cytologic and histologic findings among in PE, and specimens obtained from fine-needle aspiration and core-needle biopsy. In addition, the present results were reviewed in comparison with those of previous bovine and human reports. CASE PRESENTATION: A 58-day-old male Japanese black calf presented first with scrotal swelling, followed by progressive abdominal distention. Abnormalities of the case included: 1) accumulation of anechoic PE inside the swollen scrotum and abdomen; 2) formation of multiple echogenic nodules within the peritoneal membrane based on US images; 3) presence of hyper-dense spots (suspected calcification) along the margins of the nodules; 4) anatomic connections between intra-abdominal nodular lesions and the swollen tunica vaginalis via the inguinal region based on CT images; 5) serosanguineous-colored and less-turbid characteristics of PE; and 6) formation of multiple nodules over all of the serosa of the rumen as well as the peritoneal wall based on laparoscopic views. Fine-needle aspiration and core-needle biopsy were successfully performed under US and laparoscopic observations, respectively. Histology findings of the core-needle biopsy specimen appeared more indicative (characterization of tubular structures comprised of cubical or columnar abnormal mesothelial cell linings) diagnostically of peritoneal mesothelioma than did findings of the fine-needle aspiration specimen. CONCLUSIONS: To the best of our knowledge, this report is the first description of clinical applications of CT and laparoscopy to diagnose peritoneal mesothelioma in a calf. Laparoscopy enhanced the diagnostic accuracy due to clear gross visualization of the intra-abdominal abnormalities and applicability to imaging-guided core-needle biopsy.

Acute Abdominal Distension Due to Disseminated Peritoneal Neoplasia in a Rhesus Macaque (Macaca mulatta).

This report describes the clinical, radiographic, and pathologic findings in a female rhesus macaque that presented with acute abdominal distension and tympany. The macaque was euthanized after evidence of severe colonic distension on radiography and observation of widespread peritoneal adhesions on exploratory laparotomy. Gross and histopathologic evaluation revealed extensive entrapment of gastrointestinal and reproductive tracts by serosal fibrovascular proliferative tissue containing foci of endometriosis. The diagnosis of endometrial stromal sarcoma was supported by expression of CD10, Wilm tumor 1, estrogen receptor, and progesterone receptor and failure to express immunohistochemical markers characteristic of a range of differential diagnoses. In humans, this relatively uncommon neoplasm can arise from sites of endometriosis and often presents clinically as intestinal obstruction, similar to the presentation in this macaque.

Primary Myxoid Liposarcoma of the Greater Omentum in a Rhesus Macaque (Macaca mulatta).

We here report a spontaneous case of primary myxoid liposarcoma of the greater omentum with subsequent transperitoneal recurrence. The primary mass was incidentally found during an exploratory laparotomy for a presumed diagnosis of trichobezoar or phytobezoar and was removed surgically. Histopathologic examination of the mass revealed the presence of a myxoid liposarcoma. Eleven months later, recurrence with severe transperitoneal sarcomatosis of the myxoid liposarcoma was noted and confirmed by necropsy and histopathology. A review of the literature revealed that liposarcoma in NHP conforms to the behavior and prognosis of this neoplasm in humans.

Peritoneal and scrotal carcinomas of unknown origin in two bovine calves.

Two unrelated bovine beef calves, aged 2 mo and 3 mo, were presented to The Ohio State University Veterinary Medical Center because of scrotal swelling and abdominal distension. On postmortem examination, there was abundant peritoneal fluid and numerous small friable masses covering all peritoneal surfaces and extending into the scrotum via the tunica vaginalis, with no identifiable primary neoplasm. Based on light microscopy, differential diagnoses included malignant mesothelioma and anaplastic carcinoma. Immunohistochemically, the neoplasms labeled positive for cytokeratin, and negative for vimentin and calretinin. Neoplastic cells contained periodic acid-Schiff-positive, diastase-resistant cytoplasmic granules, and lacked Alcian blue-positive, hyaluronidase-negative cytoplasmic vacuoles. Ultrastructurally, the cells had features of carcinoma, including secretory granules, and lacked typical features of mesothelioma, such as long slender microvilli. Our final diagnosis was carcinoma in both calves, despite the equivocal gross and light microscopic findings. We propose that a presumptive diagnosis of peritoneal mesothelioma in bovine calves should be avoided without corroboration by a combination of histology, histochemistry, immunohistochemistry, and, if possible, electron microscopy.

Sonographic features of peritoneal lymphomatosis in 4 cats.

BACKGROUND: The metastatic spread of feline lymphoma to the peritoneum ("lymphomatosis") has been rarely reported in the literature. The sonographic features specific to this rare disease manifestation have not been described and have important treatment and prognostic considerations prompting definitive diagnosis. OBJECTIVES: To describe the ultrasonic features of feline peritoneal lymphomatosis. ANIMALS: Four cats with alimentary lymphoma and peritoneal metastasis confirmed using cytology, histology, or both. RESULTS: The sonographic features described include either a nonobstructive, focally diffuse, and circumferential intestinal mass, or an eccentric, focally diffuse, gastric mass. The intestinal and gastric lesions exhibited hypo-to-anechoic transmural wall thickening with loss of wall layering in association with discrete-to-coalescing plaques or sheets of thickened, hypoechoic tissue throughout the mesentery or omenta. All cases exhibited only small volumes of anechoic free peritoneal fluid. Three of the 4 cats also had multiple small hypoechoic nodular foci on the parietal and/or visceral peritoneal surfaces. Two cats had bilateral renomegaly because of lymphoma invasion (2/4) and 1 cat had local lymphadenopathy secondary to lymphoma invasion (1/4). CONCLUSIONS AND CLINICAL IMPORTANCE: Peritoneal lymphomatosis is a rare manifestation of lymphoma metastasis and to date appears to be associated specifically with B-cell alimentary lymphoma.

Intestinal gastrointestinal stromal tumor in a cat.

A 12-year-old, 3.6-kg, spayed female domestic shorthaired cat had a 2-month history of anorexia and weight loss. Abdominal ultrasonography and computed tomography revealed an exophytic mass originating from the jejunum with very poor central and poor peripheral contrast enhancement. On day 14, surgical resection of the jejunum and mass with 5-cm margins and an end-to-end anastomosis were performed. Histopathological examination revealed the mass was a transmural, invasive cancer showing exophytic growth and originating from the small intestinal muscle layer. Immunohistochemical analysis of tumor cells revealed diffuse positivity for KIT protein and negativity for desmin and S-100. The mass was diagnosed as a gastrointestinal stromal tumor (GIST). Ultrasonographic findings indicated the tumor probably metastasized to the liver and omentum, as seen in humans and dogs. The owner rejected further treatment at the last visit on day 192. To our knowledge, this is the first report of intestinal tumor and metastasis in feline GIST and its imaging features.

Subcutaneous malignant mast cell tumor in a Japanese macaque (Macaca fuscata).

The histopathological, immunohistochemical, and ultrastructural morphologic characteristics of a tumor in the subcutaneous tissue of the chest of a 19-year-old female Japanese macaque were investigated. Consequently, the mass was diagnosed as a malignant mast cell tumor (MCT). Tumors were present in both mammary gland portions of the anterior thorax. Both tumors showed the same histopathological findings. The tumor tissue was defined by the presence of delicate connective tissue, and the tumor cells grew in a cord-like or cobblestone pattern. The tumor cell cytoplasm was very clear. The nuclei were relatively uniform and the cells showed a low nucleus-cytoplasm ratio. The cytoplasmic granules stained blue with Alcian blue and eosinophils had infiltrated into the tumor tissue. Furthermore, immunohistochemical analysis revealed that the tumor cell membrane was positive for the anti-c-kit antibody. In ultrastructural morphologic analyses, all tumor cells showed a rich cytoplasm and, occasionally, granules wrapped in a limiting membrane of high electron density. The tumor cells had metastasized to the axillary lymph nodes, the kidney, and the peritoneum. Based on these results, the mass was diagnosed as a malignant MCT originating from the subcutaneous tissue of the chest. Since cases of MCTs in macaques are very rare, this report presents important new knowledge of neoplastic lesions in this species.

Omental leiomyosarcoma with unusual giant cells in a Beagle dog - Short communication.

A 10-year-old castrated male Beagle dog was presented with a 2-month history of intermittent vomiting and abdominal pain. The dog was referred to the Veterinary Teaching Hospital at Iwate University for further evaluation, and a splenic tumour was suspected on the basis of ultrasonography and computed tomography. Surgery identified a large, solid, light-pink mass on the greater omentum with blood-coloured ascites in the abdominal cavity, and resection was performed. Microscopically, the mass comprised spindle-shaped tumour cells and scattered osteoclast-like giant cells. Most spindle-shaped cells were positive for vimentin, desmin, and smooth muscle actin (α-SMA), whereas osteoclast-like giant cells were positive only for vimentin. On the basis of histopathological and immunohistochemical findings, a diagnosis of leiomyosarcoma was made. To the best of our knowledge, this represents the first report of leiomyosarcoma associated with osteoclast-like giant cells developing from the greater omentum in a dog.

Primary diffuse malignant peritoneal mesothelioma in a striped skunk (Mephitis mephitis).

A 10-year-old female striped skunk (Mephitis mephitis) was admitted with severe abdominal distension and lethargy. Cytological examination of the peritoneal fluid revealed activated mesothelial cells. At necropsy, numerous growing together, projecting, 2 to 20 mm in diameter tawny to white masses were scattered throughout the peritoneum including the mesentery, omentum and intestinal serosa. Microscopically, the tumor was composed of prominent papillo-tubular structures, and immunohistochemically, the spindle to polygonal-shaped tumor cells with nuclear polymorphism were strongly reactive for calretinin. Based on those diagnostic features, the neoplasia was diagnosed as malignant mesothelioma. This is the first case report of mesothelioma in the skunk.