Mammary adenocarcinoma in a male squirrel monkey (Saimiri sciureus)

A nodule was identified within the right mammary gland of a 16-year-old male squirrel monkey (Saimiri sciureus). The mass was excised and diagnosed as a mammary adenocarcinoma. The monkey developed congestive heart failure 1.5 years later and was euthanatized. At necropsy, a subcutaneous mass was found in the right axillary region. Histologically, the mass was identified as a lymph node whose architecture was effaced by neoplastic cells resembling those of the mammary tumor. Metastasis to internal organs was not observed. This is the first reported case of a mammary tumor in a New World primate and the only known case of mammary cancer in a male nonhuman primate.     

Frequency of an accessory popliteal efferent lymphatic pathway in dogs

Staging and therapeutic planning for dogs with malignant disease in the popliteal lymph node are based on the expected patterns of lymphatic drainage from the lymph node. The medial iliac lymph nodes are known to receive efferent lymph from the popliteal lymph node; however, an accessory popliteal efferent pathway with direct connection to the sacral lymph nodes has also been less frequently reported. The primary objective of this prospective, anatomic study was to describe the frequency of various patterns of lymphatic drainage of the popliteal lymph node. With informed client consent, 50 adult dogs with no known disease of the lymphatic system underwent computed tomographic lymphography after ultrasound‐guided, percutaneous injection of 350 mg/ml iohexol into a popliteal lymph node. In all 50 dogs, the popliteal lymph node drained directly to the ipsilateral medial iliac lymph node through multiple lymphatic vessels that coursed along the medial thigh. In 26% (13/50) of dogs, efferent vessels also drained from the popliteal lymph node directly to the internal iliac and/or sacral lymph nodes, coursing laterally through the gluteal region and passing over the dorsal aspect of the pelvis. Lymphatic connections between the right and left medial iliac and right and left internal iliac lymph nodes were found. Based on our findings, the internal iliac and sacral lymph nodes should be considered when staging or planning therapy for dogs with malignant disease in the popliteal lymph node.     

Lymphocytosis and lymphadenopathy in a dog arising from two distinct lymphoid neoplasms

A 10-year-old intact male Golden Retriever was presented to The Ohio State University Veterinary Medical Center for acute, non-painful facial swelling of the right mandibular region. On physical examination, the right mandibular swelling was found to represent marked lymphadenopathy of the submandibular lymph node. At this time, marked lymphadenopathy of the prescapular and popliteal lymph nodes was also appreciated. The CBC showed a moderate leukocytosis (38.4 × 10⁹ cells/L, reference interval [RI] 4.8-13.9 × 10⁹ cells/L) characterized by a moderate lymphocytosis (28.4 × 10⁹ cells/L, RI 1.0-4.6 × 10⁹ cells/L). Evaluation of peripheral blood and enlarged prescapular and popliteal lymph nodes revealed two morphologically different populations of homogeneous lymphocytes, with the lymphocyte population in the lymph nodes being distinct from that in the blood smear. Flow cytometry of peripheral blood revealed CD45-, CD5+, CD4-, CD8-, variably CD21+ neoplastic lymphocytes compatible with T-zone lymphocytes due to the absence of CD45 expression. Flow cytometry of the lymph node aspirate indicated a distinct population of CD21+ lymphocytes consistent with a B-cell phenotype along with a smaller proportion of the T-zone lymphocytes observed in the blood confirming the presence of two distinct populations of neoplastic lymphocytes, one involving T cells, and the other involving B cells.     

Comparison of Computed Tomographic and Radiographic Popliteal Lymphangiography in Normal Dogs

Objective: To (1) describe computed tomographic (CT) popliteal lymphangiography; (2) compare the number of thoracic duct (TD) branches detected by CT and by radiography after popliteal lymphangiography; and (3) to compare the number of branches detected after left and right popliteal lymphangiography. Study Design: Experimental study. Animals: Adult dogs (n=6). Methods: A randomly selected popliteal lymph node was percutaneously injected with 12 mL iodinated contrast medium through a 25‐g butterfly catheter over 4–5 minutes. Lateral and ventrodorsal (VD) thoracic radiograph projections and thoracic CT were performed. The procedure was repeated using the contralateral lymph node after a 48–72 hours washout period. Results: One dog had TD branches visible on CT but not on radiographs. A significantly greater number of TD branches were observed with CT popliteal lymphangiography compared with lateral and VD radiographic popliteal lymphangiography (P=.003 and P<.001, respectively). The number of visible TD branches observed between the 6th thoracic and 1st lumbar vertebrae were not significantly different in these dogs (P=.146). A significant difference in number of TD branches observed was not found after left or right popliteal lymph node injection (P=.097). Conclusions: CT popliteal lymphangiography consistently identified a greater number of TD branches when compared with radiographic popliteal lymphangiography. Injection of either popliteal lymph node resulted in the same number of TD branches being observed.     

Malignant histiocytosis in cattle

Malignant histiocytosis was diagnosed in 4 cows. In all cases the tumor tissues were composed of cytologically atypical histiocytes with evidence of erythrophagocytosis. The tumor in case 1 appeared highly anaplastic with marked nuclear pleomorphism, and had areas of spindle cell differentiation, but had no relation to malignant fibrous histiocytoma. The neoplastic tissue in case 2, characterized by cohesive growth of tumor cells, was distinguishable from anaplastic carcinoma cells by cytokeratin immunostaining. There were many hemosiderin-laden neoplastic cells suggestive of high phagocytic activity in a lymph node of case 3. The neoplastic cells in case 4, frequently multinucleated, were less atypical than in the other cases. All cases expressed histiocyte-associated markers (lysozyme and HAM56), and were negative for cytokeratin, S100, and T- and B-cell lineage-specific markers (CD3 and CD79a). The most frequent HAM56 immunoreactivity was detected in case 4, and the giant, multinucleated forms, reminiscent of epithelioid cell differentiation. seemed not to indicate cytological pleomorphism as a result of neoplastic transformation.     

A neuroendocrine carcinoma of undetermined origin in a dog

In this report, we describe a case of neuroendocrine carcinoma of undetermined origin in a dog. Necropsy revealed scattered small neoplastic nodules in the bilateral lungs and a small nodule in the parapancreatic lymph node. Histopathologically, both pulmonary and lymph nodal nodules showed a similar histologic pattern, with neoplastic cells being arranged in diffusely proliferating sheet-like cellular nests separated by variable amounts of fibrous septa, sometimes forming rosettes and duct-like structures. Scattered small necrotic foci and invasion to fibrous septa were typically observed. Neoplastic cells showed round to oval-shaped nuclei with prominent nucleoli and abundant eosinophilic cytoplasm that were positive for Grimelius' silver impregnation staining and immunostaining with cytokeratin, synaptophysin, vasoactive intestinal peptide and chromogranin A, indicative of the development of a neuroendocrine carcinoma. However, judging from the distribution of tumors lacking the portion suggestive of the primary site in any organ examined, as well as no further indication of differentiation potential of neoplastic cells, this tumor has so far been diagnosed as neuroendocrine carcinoma of undetermined origin.     

Primary osseous melanoma in the tibia of a dog

An 18-month-old, female Cane Corso dog was presented with a suspected primary tumor of the tibia. Plain radiographs and computed tomography (CT) of the tibia were highly suggestive of a primary bone neoplasm. A diagnosis of malignant melanoma was made by cytology. Total body survey radiographs, CT scan of the thorax, and abdominal ultrasound excluded the presence of neoplastic lesions other than in the tibia. Limb amputation was performed. Histology and immunohistochemical analysis of the tibial neoplasm confirmed the diagnosis of a melanoma with secondary metastasis to the popliteal lymph node. The dog was alive and in good physical condition 43 months after surgery.     

Phycomycosis in a dog.

Chronic vomiting in a 2-year-old dog was suspected to be due to a neoplasm of the stomach wall. During exploratory laparotomy, a lymph node from the pyloric area was examined microscopically. Inasmuch as neoplastic cells or evidence of metastasis were not found, all visibly involved tissue was removed surgically. A diagnosis of phycomycosis was then established by histologic evaluation of the tissue removed. It was concluded that diagnosis of this disease is important inasmuch as it may be treated successfully, in contrast to the situation with malignant neoplastic conditions, which it grossly resembles.     

Clinical,cytologic, and histologic features of a mammary micropapillary carcinoma in a dog

Mammary invasive micropapillary carcinoma is a rare variant of mammary carcinoma that was recently recognized in dogs. The cytologic features and biologic behavior of such neoplasms in dogs have not yet been widely discussed in the veterinary literature. We report the clinical, cytologic, and histologic features of a canine micropapillary carcinoma in a 13‐year‐old female mongrel dog. The mammary region presented with extreme local pain, severe edema and erythema, and multifocal epidermal ulceration, which is typical for an inflammatory mammary carcinoma. Fine‐needle aspirates were highly cellular and consisted of individual cells and papillary cell clusters with characteristics of malignant epithelial cells. Histologic examination revealed neoplastic cells arranged in small papillae without fibrovascular cores, sometimes inside clear lymphatic spaces, indicating lymphovascular invasion. Regional lymph node evaluation revealed metastatic cells. Due to deteriorating clinical condition the dog was euthanatized 5 months after mastectomy. At necropsy, metastatic neoplastic mammary cells were found in popliteal and mediastinal lymph nodes, the right femoral biceps muscle, liver, heart, lungs, and urinary bladder.     

Morphologic characteristics of a transplantable tumor derived from a spontaneous malignant fibrous histiocytoma in the rat

Malignant fibrous histiocytoma (MFH) developed spontaneously in subcutaneous tissue of the head of a 15-month-old male Fischer 344 rat. The tumor was serially transplanted into syngeneic rats up to the 45th generation and was designated MFH-MT. Light and electron microscopic examinations revealed that the original and serially transplanted tumors were composed of an admixture of fibroblast-like and histiocyte-like cells arranged in a storiform pattern. Neoplastic cells gave positive reactions for acid phosphatase, alkaline phosphatase, nonspecific esterase, alpha-1 antitrypsin and lysozyme. The tumors transplanted into the lungs and cutaneous tissue of the tail had a mixed histologic appearance of storiform, pleomorphic, myxoid and giant cell types. Moreover sclerosing hemangioma-like and osteosarcoma-like structures were also found. MFH-MT grew well in athymic nude mice showing neoplastic proliferation of pleomorphic cells strongly positive for alpha-1 antitrypsin. Development of MFH-MT was significantly retarded by the two antitumor drugs tested. The retarded tumors consisted predominantly of fibroblast-like cells and abundant collagenic fibers, whereas histiocytic cells decreased in number.     

The lymph drainage of the neoplastic mammary glands in the bitch: a lymphographic study

The purpose of this investigation was to study the lymph drainage of the neoplastic mammary glands in the bitch using indirect lymphography. The main conclusions drawn from the study of 41 natural cases were as follows: the first or cranial thoracic and second or caudal thoracic neoplastic mammary glands usually drain into the ipsilateral axillary lymph nodes and rarely into the ipsilateral axillary and sternal lymph nodes, simultaneously. The third or cranial abdominal neoplastic mammary gland usually drains into the ipsilateral axillary and superficial inguinal lymph nodes simultaneously, but sometimes only cranially into the ipsilateral axillary lymph nodes. Rarely, it drains only caudally into the ipsilateral superficial inguinal and medial iliac lymph nodes, simultaneously. The fourth or caudal abdominal neoplastic mammary gland usually drains only caudally into the ipsilateral superficial inguinal lymph nodes. Rarely, it drains into the ipsilateral axillary and superficial inguinal lymph nodes simultaneously. The fifth or inguinal neoplastic mammary gland usually drains into the ipsilateral superficial inguinal lymph nodes but rarely, does it also drain into the ipsilateral popliteal lymph node and into a lymphatic plexus at the medial aspect of the ipsilateral thigh. Lymphatic connections between the neoplastic and adjacent normal mammary glands were demonstrated in only one case. The lymph drainage pattern of the neoplastic mammary glands is slightly different to that described in normal glands using the same radiographic method.     

Lymphography of the thoracic duct by percutaneous injection of iohexol into the popliteal lymph node of dogs: experimental study and clinical application

OBJECTIVE: To evaluate the efficacy of percutaneous administration of iohexol into the popliteal lymph node as a non-invasive technique for thoracic duct lymphangiography in dogs. STUDY DESIGN: Experimental study and clinical report. ANIMALS: Normal adult dogs (n=4) and 1 dog with recurrent chylothorax. METHODS: For the experimental study, 4 dogs (weight, 8.4-12.3 kg) had 5-10 mL iohexol injected percutaneously into 1 popliteal lymph node and then thoracic radiographs were taken. Popliteal lymph nodes were examined by histopathology 8 days later. One 25-kg dog with recurrent chylothorax had 25 mL iohexol injected into the right popliteal lymph node followed by thoracic radiography. RESULTS: In experimental dogs, the thoracic duct was best visualized on thoracic radiographs after administration of 10 mL iohexol. Clinically, no abnormalities were identified in the injected limb and except for 1 dog that had large numbers of siderocytes and erythrophagocytic macrophages in the injected lymph node, the histopathologic findings in the other injected popliteal lymph nodes were not different from contralateral nodes. In the clinical case, the thoracic duct was visualized, but there was leakage of iohexol around the node. CONCLUSION: The thoracic duct in dogs can be visualized by lymphography after percutaneous injection of iohexol (1 mL/kg at 2 mL/min) into the popliteal lymph node. CLINICAL RELEVANCE: Percutaneous popliteal lymph node administration of iohexol should be considered as an alternative to mesenteric lymph node injection for radiographic identification of the thoracic duct in dogs.     

Pathological findings of Japanese Black Cattle living in the restricted area of the Fukushima Daiichi Nuclear Power Plant accident, 2013–2016

Fifty‐one Japanese black cattle from four farms in the evacuation zone of the Fukushima nuclear accident were examined pathologically during the period, 2013–2016. We found no evidence of a radiation effect on pathological findings in any of these autopsy cases, although nine cases (3.7%) of enzootic bovine leukosis (EBL) and three cases (1.2%) of goiter were diagnosed. Estimated integrating dose of external exposure in EBL cases ranged from a maximum of 1200 mSv to a minimum of 72 mSv. Clinically, five cases showed wobble, dysstasia or paralysis. Exophthalmos was observed in three cases. Macroscopically, enlarged lymph nodes, multiple irregular masses of intra‐abdominal and intrapelvic adipose tissue, diffuse thickening of the abomasal submucosa with ulceration, and numerous white nodules of myocardium were observed. Histologically, neoplastic lymphoid cells were extensively proliferated and infiltrated in the lesions. Lymphoid tumor cells showed mature or large lymphoblastic appearance. Immunohistochemically, tumor cells were positive for BLA‐36, CD20 and CD5, and negative for CD3. Three cases showed diffuse enlargement of the thyroid gland with no mass or nodule lesion. Histologically, diffuse proliferation of follicular epithelium was observed with preservation of normal structures. There were no malignant findings such as cellular atypia or invasion to capsule.     

Disseminated haemangiosarcoma in an eastern barred bandicoot (Perameles gunnii)

A captive adult male Eastern barred bandicoot (Perameles gunnii) presented with three palpable subcutaneous masses in November 1998. A diagnosis of haemangiosarcoma was made based on histological examination of one excised mass. Euthanasia of the animal was performed 11 days postsurgery and a proliferative lesion in the paralumbar musculature and similar, smaller proliferative lesions surrounding the right popliteal lymph node and in the ventricular wall of the heart were found. Metastatic lesions were found in the liver and lung. The histological features of the neoplastic tissues supported the diagnosis of a poorly differentiated, disseminated haemangiosarcoma. This is the first reported case of haemangiosarcoma in the Eastern barred bandicoot.     

RESULTS OF RADIATION THERAPY IN 19 DOGS WITH CUTANEOUS MAST CELL TUMOR AND REGIONAL LYMPH NODE METASTASIS

The records of 19 dogs with cutaneous mast cell tumor and regional lymph node metastasis (WHO Stage 2) were reviewed to determine the efficacy of radiation therapy in this population. Dogs with grade I (n = 1), grade II (n = 16), and grade III (n = 2) cutaneous mast cell tumor were included in this study. All dogs were treated with a combination of pre-irradiation surgical cytoreduction of the primary tumor, irradiation of the primary tumor and regional lymph node, and oral prednisone. Total radiation dose to the primary tumor and regional lymph node ranged from 48 to 57 Gray (Gy). The medial iliac and hypogastric lymph nodes were irradiated prophylactically in 11 dogs with primary tumor of the pelvic limb and positive ipsilateral popliteal lymph node. Total radiation dose to these lymph nodes ranged from 48 to 57 Gy. For all radiation fields, dose per fraction was 3 Gy, and therapy was administered on a Monday through Friday schedule. Acute and late radiation side effects observed in this study were considered acceptable. The median disease-free survival was 1,240 days (95% confidence interval 256 to 2,391 days). The disease-free survival in dogs with stage 2 mast cell tumor suggests that the combination of surgery, irradiation, and prednisone for the primary tumor along with irradiation of the positive lymph node is effective.     

Response of efferent lymph and popliteal lymph node to epidermal infection of sheep with orf virus

Functional and phenotypic changes in the cell populations were monitored in the popliteal efferent lymph of sheep following experimental epidermal infection with orf virus. In another group of sheep, cells from the popliteal lymph node draining the site of infection were similarly monitored and compared with the cells from contralateral popliteal and mesenteric lymph nodes. All sheep showed serological evidence of previous exposure to orf virus. Following infection, anti-orf antibody titres rose and efferent lymphocyte and blast cell output increased. Interferon-like activity was detected in efferent lymph early after orf virus but not mock infection. Lymphocytes from the draining popliteal lymph node showed antigen-specific lymphoproliferation on Days 3-7 while cells in the efferent lymph demonstrated proliferative activity on Days 4-6. The requirement for exogenous antigen-presenting cells in the culture of efferent lymphocytes varied between individual sheep. The culture supernatant from proliferating lymph node cells contained interferon-like activity but no anti-orf antibodies, the reverse of that from cultured efferent lymphocytes, perhaps indicating a different reactive T cell population. During the course of the experiment there was an increase in the percentage of efferent lymphocytes expressing MHC Class II antigens and surface immunoglobulins, the latter being recorded as a double peak. The short-term nature of the local T cell response may in part explain the incompleteness of immunity to orf virus in sheep.     

Utility of polymerase chain reaction for analysis of antigen receptor rearrangement in staging and predicting prognosis in dogs with lymphoma

In lymphoid neoplasia, molecular assays to confirm clonality rely on the fact that lymphoid cells normally contain DNA regions with unique sequences, resulting from recombination of the V, D, and J genes. The purpose of this study was to determine the utility of polymerase chain reaction (PCR) for antigen receptor rearrangements (PARR) for molecular staging and predicting prognosis in canine lymphoma. We hypothesized that the PARR assay would offer a sensitive method for detecting neoplastic cells in blood, and that the presence of such cells would be a negative prognostic finding compared with dogs with no detectable circulating tumor cells. Eighty-six patients with histologically or cytologically confirmed lymphoma were studied from initial diagnosis until death or euthanasia. All patients had PARR assays of a representative tumor-infiltrated lymph node and peripheral whole blood. Sixty-two patients had clonal rearrangements detected in the lymph node and were able to be staged by PARR. Seventeen patients (27%) had no detectable tumor in their blood and 45 (73%) were blood positive. Our findings showed that (1) PARR correlated with clinical stage in that the PARR assay was more likely to detect tumor cells in blood in stage 5 lymphomas, (2) PARR was more sensitive for detecting circulating tumor cells than visual assessment of blood or bone marrow because 80% of stage 3 lymphomas were blood-PARR-positive, and (3) PCR stage was not prognostic for disease-free interval (DFI) or survival.     

Lymphangiosarcoma in a 3.5-year-old Bullmastiff bitch with vaginal prolapse, primary lymph node fibrosis and other congenital defects

Lymphangiosarcoma is an extremely rare tumour in dogs with only 16 cases reported in the literature. Lymphoedema, which may be primary due to defects in the lymphatic system, or secondary to various other pathologies, often precedes malignancy. Of the 16 canine reports, only 1 dog was confirmed as having had prior primary lymphoedema due to aplasia of the popliteal lymph nodes. A case of lymphangiosarcoma is described in a 3.5-year-old purebred, Bullmastiff bitch which presented with vaginal blood 'spotting' for 3 weeks after cessation of oestrus, during which intromission by the male had been unsuccessful. During ovariohysterectomy a large multicystic, proliferative, spongy, fluid-filled, brownish-red mass surrounding the cervix and projecting into the abdominal space was removed with the cervix, and a diagnosis of lymphangiosarcoma made on histological and electron microscopic examination of the tissue. Ultrastructurally, no basement membrane or pericytes were found, only some of the neoplastic endothelial cells were linked by tight junctions while there were gaps between others, and neither micropinocytotic vesicles nor Weibel-Palade bodies occurred in the cells examined. Very few of the endothelial cells lining the many interlinking, tortuous maze of channels, stained slightly positive immunohistochemically for factor VIII-related antigen. The channels were filled mostly with serous fluid, and occasionally mixed leucocytes and some erythrocytes. The endothelium was often associated with underlying blocks of collagenous material, as well as loosely-arranged aggregates of lymphocytes, other mononuclear cells and occasional neutrophils in the connective tissue septae and more prominently perivascularly. The bitch was discharged on antibiotic treatment but returned 2 weeks later with apparent prolapsed vagina which failed to reduce over the next week. Laparotomy revealed the tumour to have spread extensively in the caudal abdomen to involve the broad ligament and the ventral rectal serosa, and the 'prolapsed' tissue was found to be expanded vaginal wall. The bitch was euthanased and necropsied, Histological examination confirmed lymphangiosarcomatous invasion of the submucosal and muscular layers of the retroperitoneal, traumatised, prolapsed part of the vagina, the urethra and the ventral rectal wall. The broad ligament was diffusely invaded with tumour which had proliferated into the caudal abdominal space, and 3 small intra-trabecular foci of tumour were found in the right popliteal lymph node near the hilus. Mitotic figures were generally scarce. There was mild subcutaneous oedema of the ventral trunk extending from the axillae to the inner proximal thighs, which had not been evident clinically, and the lymph nodes (peripheral more so than internal) microscopically showed marked trabecular and perivascular fibrosis especially in hilar regions. Other congenital defects were hepatic capsular and central venous fibrosis with lymphatic duplication and dilatation in all areas of connective tissue, ventrally-incongruous half-circular tracheal rings, and multifocal renal dysplasia affecting the right kidney. There was locally-extensive subacute pyelonephritis of the left kidney.