Immunohistochemical staining patterns of canine meningiomas and correlation with published immunophenotypes

This study examined immunohistochemical staining patterns for several meningioma variants involving either the brain or spinal cord of dogs. Formalin-fixed, paraffin-embedded tissue from 15 tumors was obtained. The selected tumor group included seven meningothelial, three transitional, two malignant (anaplastic), one myxoid, one papillary, and one osteomatous meningiomas. Tumors were evaluated for reactivity to the following six immunohistochemical markers: vimentin, pancytokeratin, glial fibrillary acidic protein (GFAP), S100, neuron-specific enolase (NSE), and synaptophysin. Vimentin expression was detected in all meningiomas, and 14 of 15 tumors demonstrated intense vimentin staining in more than 50% of the neoplastic cells. Pancytokeratin expression was present in 11 of 15 neoplasms; however, positive staining frequently was focal and often involved a small percentage of the neoplastic cells. GFAP expression was detected in a single, anaplastic meningioma. Although expression of NSE and S100 was detected in 12 of 25 meningiomas, the intensity of the staining and the percentage of positive neoplastic cells was highly variable. Synaptophysin was uniformly negative. These results will help to establish immunohistochemical profiles for meningiomas that will improve our ability to correctly differentiate these neoplasms of meningeal origin from central nervous system tumors originating from other sites.     

Identification of immunoglobulin light chains in canine extramedullary plasmacytomas by thioflavine T and immunohistochemistry

Extramedullary plasmacytomas were studied in 29 dogs. The site at which tumors occurred and the age and sex of the dogs were similar to those in previous reports. The skin of the digits, chin, ear, and lip represented the most common (17/29) tumor sites. Males and females were equally represented, and tumors occurred in middle-aged to old dogs (mean age, 9.0 years). A breed predilection was seen in the Cocker Spaniel (n = 7; 24%); Cocker Spaniels represented only 4% (210/4,725) of the submissions during the same period. Tumors were stained with immunohistochemical markers (lambda light chain, K light chain) and thioflavine T. Immunoreactivity was limited to either lambda or K light chains, consistent with a monoclonal plasma cell population. The majority of tumors expressed lambda light chains, consistent with previously reported canine plasma cell dyscrasias. Thioflavine T cytoplasmic fluorescence was seen in the majority (18/29) of plasmacytomas and with inflammatory plasma cells present in control specimens. Other round cell neoplasms (lymphosarcoma, histiocytoma, and mastocytoma) were negative with thioflavine T, indicating that positive staining with thioflavine T was specific for plasma cells (neoplastic and inflammatory). This study confirms by immunohistochemistry that canine extramedullary plasmacytomas disproportionately express lambda light chains and establishes thioflavine T staining as a rapid histochemical method for diagnosis of these tumors.     

Canine ovarian neoplasms: a clinicopathologic study of 71 cases, including histology of 12 granulosa cell tumors

In a retrospective study of 71 primary ovarian tumors in the dog, epithelial tumors (46%) were more common than sex cord stromal (34%) and germ cell tumors (20%). There were more adenocarcinomas (64%) than adenomas. Sex cord stromal tumors were equally divided into Sertoli-Leydig (12/24) and granulosa cell tumors (12/24). There were equal numbers (7/14) of dysgerminomas and teratomas among the germ cell tumors. Most teratomas (6/7) were malignant. Most granulosa cell tumors were solid; two were mostly cystic. Patterns included sheets of round and ovoid to spindle-shaped cells separated by thin, fibrovascular stroma; neoplastic cells formed rosettes or Call-Exner bodies. In some areas, neoplastic cells were in cords or columns and formed cyst-like structures. Four granulosa cell tumors were macrofollicular, having cysts lined with granulosa cells. Median ages of dogs with different ovarian neoplasms were similar; all were more than 10 years old, except the dogs with teratoma (mean age, 4 years). Most neoplasms were unilateral (84%), except the Sertoli-Leydig cell tumors, many of which were bilateral (36%). Size of ovarian neoplasms varied (2 cm3 to 15,000 cm3). Twenty-nine percent of neoplasms metastasized; adenocarcinomas (48%) and malignant teratomas (50%) had the highest rates, and distant metastasis was more common in malignant teratoma. Endometrial hyperplasia was in 67% of the dogs; it was most common in dogs with sex cord stromal tumors (95%). Uterine malignancy was not seen in dogs with granulosa cell tumors, although hyperplasia endometrium was in all dogs with this tumor. Cysts in the contralateral ovaries were most common in dogs with sex cord stromal tumors.     

Clinico-pathological aspects of canine cutaneous and mucocutaneous plasmacytomas

In this study the clinico-pathological aspects of cutaneous and mucocutaneous plasmacytomas were investigated in 63 dogs (one dog with two tumours). The tumours were most commonly observed in the skin of the trunk and legs. Yorkshire Terrier (n = 8) was the most commonly affected breed and males were affected more commonly than females (36 versus 23, respectively). Plasmacytomas were histologically classified into mature, hyaline, cleaved, asynchronous, monomorphous blastic and polymorphous blastic cell types. Monomorphous blastic cell type was the most frequent type (n = 21), followed by cleaved (n = 19) and asynchronous (n = 11) cell types. Secondary amyloid depositions were observed in eight cases. Immunohistochemical staining showed monoclonal lambda light chain positivity in all cases. In the immunohistochemical staining for cyclin D1, which is a prognostic marker in human plasma cell tumours, moderate numbers of positive tumour cells were observed in only one case of (muco)cutaneous plasmacytoma. All other cases were negative or contained few positive tumour cells. On the other hand, high numbers of tumorous plasma cells reacted positively with cyclin D1 in three out of six cases of canine multiple myelomas. Prognosis of the (muco)cutaneous plasmacytomas was good, except in one dog which developed a lymphoma afterwards. No significant correlations were observed between the cell type and the location of the tumour, presence of amyloid or prognosis.     

Gross, histologic, cytochemical, and immunocytochemical study of medullary thyroid carcinoma in sixteen dogs

The gross, histomorphologic, cytochemical, and immunocytochemical findings in 16 dogs with medullary thyroid carcinoma were evaluated. Grossly, the neoplasms were encapsulated, firm, lobulated, and grey-white to tan. The typical histologic pattern was groups or sheets of round to polygonal cells with fibrovascular stroma, which was thickened and hyalinized in places. Variants of clear cell (two dogs), giant cell (one dog), and oxyphil cell (one dog) types were also seen. In all 16 dogs, Grimelius-stained sections of the neoplasms revealed intracytoplasmic silver granules; ten tumors contained amyloid and four contained mucin. Immunohistochemically, the neoplasms reacted to AE1/AE3 (n = 13), S-100 protein (n = 5), neuron specific enolase (n = 14), synaptophysin (n = 11), calcitonin (n = 16), somatostatin (n = 4), gastrin (n = 7), and serotonin (n = 6). Only one neoplasm was positive for vimentin. None of the neoplasms reacted to antibodies for neurofilaments, thyroglobulin, insulin, glucagon, or adrenocorticotrophic hormone. Eleven neoplasms contained multiple (two to four) peptides, in various combinations. It was concluded that in dogs, gross and histologic features can be used to distinguish medullary thyroid carcinoma from other thyroid malignancies. Cytochemical and immunocytochemical studies with neuron specific enolase, synaptophysin, and calcitonin can be used to establish the diagnosis of medullary thyroid carcinoma in dogs.     

Renal amyloidosis in related English foxhounds

Renal amyloidosis was diagnosed in six related English foxhounds from two separate hunting kennels. There was no apparent age or sex predilection. All the dogs had clinical and laboratory findings compatible with renal disease. The onset of clinical signs was acute in all cases with death or euthanasia in five of the six affected dogs occurring within one week of presentation. The remaining dog was treated with diuresis which produced a temporary improvement. Histological examination of renal tissue from affected dogs identified the presence of both glomerular and interstitial amyloid, which was confirmed by immunohistochemical staining to be of the reactive type (amyloid A). There were occasional sclerosed glomeruli or glomeruli with thickened Bowman's capsules, in addition to interstitial and periglomerular infiltration with a predominance of plasma cells and lymphocytes and secondary changes including tubular eosinophilic casts. Renal papillary necrosis was identified in three dogs. One hound had concurrent multicentric lymphoma. Pedigree analysis of the affected dogs revealed that four individuals shared a common great grandsire and that the same dog was the grand-sire of a further case. Pedigree analysis of five additional dogs from one of the kennels, all of which had clinical signs of acute renal failure but from which renal tissue was not available, revealed a close relationship to those foxhounds with confirmed renal amyloidosis.     

Hyalinizing pancreatic adenocarcinoma in six dogs

Exocrine pancreatic carcinoma is a particularly malignant neoplasm of the dog. Clinical and pathologic findings of an unusual variant of exocrine pancreatic neoplasia termed hyalinizing pancreatic adenocarcinoma were evaluated in 6 dogs. On microscopic examination, neoplasms were composed of tubules and acini of epithelial cells, with bright eosinophilic granular apical cytoplasm. Tubular lumina and tumor stroma contained abundant hyaline material that resembled amyloid. The hyaline material was not congophilic, and tumor cells and hyaline material were immunohistochemically negative for amyloid A, immunoglobulin light chains (kappa and lambda), amylin (islet amyloid polypeptide), laminin, and alpha(1)-antitrypsin. Two patients survived longer than 15 months after diagnosis; one of these dogs was untreated and had grossly evident metastasis at the time of diagnosis. The deaths of the other 4 dogs occurred as a result of poor recovery after partial pancreatectomy or in association with other concurrent life-threatening conditions. Two dogs were diagnosed with panniculitis, a condition rarely associated with pancreatic disease. Further evaluation is needed to determine the composition and biologic significance of intratumor hyaline material. Studies that associate exocrine pancreatic carcinoma grade and histologic subtype with prognostic outcomes in the dog are warranted such that appropriate therapy can be elected.     

Canine carcinosarcomas in the head

Four cases of neoplasms in the heads of old dogs were studied. All the dogs showed both carcinomatous and sarcomatous malignant components in an admixed growing pattern. Histologic analysis of the tumors showed that the carcinomatous cells resembled squamous cell carcinoma in all dogs except one, where an adenoid arrangement of the neoplastic cells was also observed. The sarcomatous component showed osteoid matrix produced by pleomorphic poorly differentiated cells, which is regarded as a typical feature of osteosarcomas. Immunohistochemical analysis demonstrated that the components were positive only for cytokeratin (carcinomatous component) or vimentin (sarcomatous component). This observation led us to classify the neoplasms as true carcinosarcomas, thus providing evidence of a new preferential location for this unusual tumor in dog.     

Immunohistochemical detection of inhibin-alpha, -betaB, and -betaA chains and 3beta-hydroxysteroid dehydrogenase in canine testicular tumors and normal testes.

Immunohistochemical detection of inhibin-alpha, -betaA and -betaB chains and 3beta-hydroxysteroid dehydrogenase (HSD) was carried out on primary testicular tumors from 15 dogs and normal testes from three adult dogs. Histopathologically, the tumors were composed of three types: Leydig cell tumors in five dogs, Sertoli cell tumors in five dogs, and seminoma in five dogs. In normal testes, immunostaining against inhibin-alpha, -betaA, and -betaB chains and 3beta-HSD revealed positive reactivity in the cytoplasm of Leydig cells. In testicular tumors, immunoreactive cells against inhibin-alpha, -betaA, and -betaB chains and 3beta-HSD were localized in all Leydig cell tumors but not in any Sertoli cell tumors or seminomas. The results of radioimmunoassay for plasma inhibin in dogs with Leydig cell tumors showed higher concentrations than those in dogs with Sertoli cell tumors and seminomas and those in normal dogs. The concentration of inhibin in the plasma was markedly decreased by the surgical removal of the Leydig cell tumor in one dog. Our findings suggest that inhibin is synthesized by normal and neoplastic Leydig cells in the canine testis, and the secreted inhibin may be inhibin A and inhibin B.     

Histopathologic and immunophenotypic characterization of extramedullary plasmacytomas in nine cats

To contribute to the existing body of knowledge in the literature on the apparently rare extramedullary plasmacytoma in cats, lymphoid tumors with plasmacytic cellular morphology taken from nine cats were examined. The paraffin-embedded material was investigated by standard hematoxylin and eosin, and special staining techniques (Giemsa, Congo-red, and periodic acid-Schiff reaction). The tumors also were examined immunohistochemically for the presence of immunoglobulin G, immunoglobulin A, immunoglobulin M, immunoglobulin light chains (lambda, kappa), various amyloid proteins, and FeLV-antigen (p27 protein). An immunoglobulin-producing tumor of plasmacellular origin (extramedullary plasmacytoma [EMP]) could be diagnosed in all cases on the basis of immunohistochemical light-chain expression. All but one of the neoplasms occurred in the skin of older, predominantly male cats. As in humans and dogs, the following types could be identified according to their morphologic features: mature type (two), cleaved type (two), asynchronous type (four), and polymorphous type (one). The tumor tissue of three cats revealed amyloid deposits, which were immunohistochemically diagnosed as ALlambda-amyloid in all three cases.     

Characterization of lymphocytes in canine gastrointestinal lymphoma

Primary canine gastrointestinal lymphoma has been believed to be of B-cell origin based on the morphology and behavior of the neoplastic cells and the evidence from the human medical field. However, the neoplasms have not to date been characterized as to the origin of the cell population. Forty-four cases diagnosed as canine gastrointestinal lymphoma were retrieved from the records of the Veterinary Teaching Hospitals at the University of Minnesota and the University of Wisconsin-Madison. Four of the cases have been previously identified as epitheliotropic T-cell gastrointestinal lymphoma. Twenty-three of the dogs were female, with 11 intact and 12 neutered, and 21 of the dogs were male, with 12 intact and nine neutered. Sixteen breeds as well as individuals of mixed breeding were represented. The Boxer and the sharpei were the most commonly represented breeds with six individuals each. The age range of the dogs was 1.5-14.66 years, with two dogs identified as adult and two of unknown age. Archived tissue blocks of gastrointestinal samples were sectioned in duplicate and prepared for immunohistochemical staining with CD3 (T-cell marker) and CD20 (B-cell marker). In 75% of the cases examined under light microscopy, 50-95% of the neoplastic cells stained positively with CD3 and exhibited marked epitheliotropic behavior. In three of the cases, from 10% up to 50% of the neoplastic cells stained positively with CD20, with widely scattered CD3(+) cells. In the remainder of the cases, few to none of the neoplastic cells stained with either of the markers. This retrospective study shows that canine primary gastrointestinal lymphoma is more commonly of T-cell origin, rather than B-cell origin.     

Immunohistochemical study of expression of immunoglobulins in canine B-cell lymphomas

Nineteen canine lymphomas were included in this study. Tumors were classified according to the updated Kiel classification adapted for canine lymphomas by Fournel-Fleury et al. Immunoglobulin light chains (kappa and lambda) and IgM and IgG expression were determined by immunohistochemical method. In all examined cases neoplastic cells were positive for one of the immunoglobulin light chains. Expression of lambda light chains and kappa light chains was observed in 18/19 and 1/19 tumors, respectively. In the majority of neoplastic cells in each examined specimen this reaction had a membranous pattern (skappa/slambda). In all examined cases the presence of immunoglobulin light chains was also observed in the cytoplasm of some neoplastic cells (ckappa/clambda). These cells were usally rare and never constituted a dominant population. The expression of immunoglobulin was found in 13/19 cases. Most lymphomas were sIgM positive (11/13 cases). In one case expression of IgG was found, and in another lymphoma two populations of neoplastic cells with different expression of examined immunoglobulins (cells with IgM+ and IgG+ phenotypes) were observed. The reaction also had a membranous pattern. The cells containing cytoplasmic immunoglobulins were rare, and in most cases were of the same type as the surface immunoglobulins. Our study has confirmed that canine lymphomas are a monoclonal proliferation of B-cells usually expressing immunoglobulin lambda light chains and that the vast majority of tumors deriving from B-cells express IgM. Our study also indicates a possibility of occurence of biclonal lymphomas in canine species.     

Canine orbital meningiomas: a review of 22 cases

Clinical and pathologic features of primary orbital meningiomas in the dog were reviewed. Twenty-two meningiomas, confined to the orbit, were identified from the Comparative Ophthalmic Pathology Laboratory of Wisconsin from 1981 to 1997. The dogs ranged in age from 3 to 17 years (mean = 9.2 years). The clinical presentation, reported in 20 cases, was indicative of a retrobulbar mass and included exophthalmos and orbital swelling (18/20), and papilledema or abnormalities of the posterior segment (7/20). Visual acuity was reported in 15 cases; of those, 12 dogs were blind in the affected eye. Follow-up information was obtained on 17 cases; six dogs developed local recurrence of the neoplasm. Two dogs with recurrent neoplasms simultaneously developed blindness in the opposite eye. Extension along the optic nerve to the optic chiasm was suspected. No metastasis was found at the time of the study. Enucleation with excisional biopsy was effective therapy to date in 11 cases (0.2–4.5 years follow-up time). All neoplasms were located within the vicinity of the optic nerve and, when sectioned through the optic nerve head, appeared to completely envelope the nerve. The neoplastic cells were arranged in tight whorls and bundles characteristic of meningiomas. Most tumors had islands of chondroid and osseous metaplasia (17/22). Ocular invasion was limited to small foci in the posterior choroid or optic nerve head of six dogs. Immunoperoxidase stains on 10 cases were positive for vimentin and S-100, but negative for cytokeratin. Electron microscopy revealed complex interdigitations between cell membranes and few desmosomal intercellular attachments. Primary orbital meningiomas have a characteristic histologic appearance and may recur locally after surgical excision.     

Localized amyloidosis in canine mammary tumors

Histopathologic and immunohistochemical examinations were performed on localized amyloidosis associated with mammary tumors in two dogs. These tumors were identified as adenoma and adenocarcinoma. An acellular, amorphous pale eosinophilic material (amyloid) was observed in the lumina of acini lined by neoplastic cells and in the stroma of the tumors. Concentrically laminated pale eosinophilic bodies (corpora amylacea) were also found in the lumina of the acini. Amyloid and corpora amylacea stained positively with Congo red with and without 5% potassium permanganate pretreatment and revealed a green birefringence under polarized light. Corpora amylacea showed an occasional Maltese-cross pattern. Immunohistochemically, amyloid and corpora amylacea usually stained positively with anti-bovine alpha-casein antibody but negatively with anti-human amyloid AA, anti-bovine kappa-light and lambda-light chains, anti-human lactoferrin, anti-human transferrin, anti-human secretory component, and anti-human polyglucosan antibodies. These findings suggested that the amyloid deposition in these canine mammary tumors was related to lactating casein.     

Serum concentrations of immunoglobulins G, A, and M in dogs with neoplastic disease

The concentrations of the three major classes of immunoglobulins (Ig) were determined in canine serum by single radial immunodiffusion against calibrated standards. Serum samples were collected from 121 dogs categorized into 3 groups: normal dogs (n = 34), those with lymphosarcoma (n =41), and those with malignant, solid neoplasms other than lymphosarcoma (n = 46). The mean value for serum IgM concentration in the group of dogs with lymphosarcoma was significantly (P less than or equal to 0.02) higher than was the mean IgM concentration of the normal dogs. Dogs with neoplasms other than lymphosarcoma had significantly increased serum concentrations of IgG and IgM antibodies. There was no significant difference in serum IgA concentration among the three groups. A wide range of Ig concentrations was in the serum of clinically normal dogs, as well as in dogs with neoplastic diseases. Although individual dogs with neoplasms had low serum Ig concentrations, the 81 dogs with neoplastic disease were generally able to synthesize Ig.     

Extramedullary plasmacytoma of the salivary gland in two Syrian hamsters (Mesocricetus auratus)

Two Syrian hamsters developed marked swelling of the ventral neck. Histologic examination of both masses revealed that the submaxillary salivary glands were effaced by large numbers of neoplastic plasma cells. In one hamster, neoplastic cells had infiltrated the adjacent lymph node. The neoplastic cells expressed CD79a antigen and were negative for CD3, lambda, and kappa light chains. Ultrastructural features of neoplastic cells in the salivary gland of one hamster included abundant cytoplasmic rough endoplasmic reticulum profiles, and peripherally displaced nuclei that contained marginated heterochromatin, consistent with plasma cells. Salivary gland plasmacytomas are extremely rare in humans and have not previously been reported in nonhuman species. The occurrence of such neoplasms in two hamsters suggests that this species may be predisposed to developing tumors of this type.     

Canine hepatocellular carcinoma

In a study of 110 primary hepatic neoplasms in dogs, 55 hepatocellular carcinomas and two combined hepatocellular and cholangiocarcinomas were diagnosed. These neoplasms were classified into the following 11 groups based on histo-architectural pattern: trabecular, peliod, cobblestone, peritheliomatous, anaplastic, pseudoglandular, pleomorphic, scirrhous, clear cell, solid, and combined hepatocellular and cholangiocarcinoma. The neoplastic hepatocytes varied from almost normal to highly anaplastic spindle cells. Pleomorphic and giant cells were common in some groups, rare or absent in others. Metastasis was found in 61% (35 of 57), in contrast to a much higher percent in man, indicating the possibility of a different pathogenesis in the dog.     

Symptomatic granular cell tumor involving the pituitary gland in a dog: a case report and review of the literature

A granular cell tumor involving the pituitary gland, optic chiasm and ventral pyriform lobes was discovered in a 12-year-old Labrador Retriever. Clinical signs included acute blindness, seizures, ataxia, weakness, and behavioral changes. The diagnosis was established by histopathologic and ultrastructural examination of neoplastic tissues collected at necropsy. Granular cell tumors involving the central nervous system are well documented in humans but rarely have been described in dogs. The location of the neoplasm and the clinical symptoms seen in this dog closely parallel those of a rare syndrome in humans commonly described as symptomatic parasellar or pituitary granular cell tumors. The cell of origin for these tumors is still highly debated, and attempts to characterize human granular cell tumors through immunohistochemistry have produced conflicting results. An immunohistochemical profile of this neoplasm revealed focal positive staining for vimentin with a lack of staining for neuron-specific enolase, glial fibrillary acidic protein, S-100, and synaptophysin. All neoplastic cells were strongly positive with the periodic acid-Schiff reaction.     

Ultrastructural characteristics of canine transmissible venereal tumor at various stages of growth and regression.

Ultrastructural study of canine transmissible tumors in developing, mature, and regressing stages from 6 dogs revealed the presence of healthy and degenerating tumor cells in all neoplasms. The total number of neoplastic cells seemed to decrease, and the number of degenerating neoplastic cells seemed to increase in mature tumors. Macrophages, lymphocytes, and plasma cells infiltrated mature and regressing tumors. Alteratons in degenerating tumor cells consisted mainly of cytoplasmic changes in early stages and of both nuclear and cytoplasmic changes in cells in which degeneration was more advanced. Amounts of endoplasmic reticulum and ribosomes were decreased. There were swelling and vacuolation of mitochondria. Nuclear chromatin was clumped along the nuclear envelope, and the perinuclear space was widened. Degenerating cells often contained membrane-bound granules and clusters. Lamellar complexes were observed in tumor cells from 2 dogs. Virus particles were not seen.     

Hypoglycemia in Four Dogs With Smooth Muscle Tumors

Tumor-associated hypoglycemia has been reported in dogs with pancreatic β-cell tumors, hepatic tumors, and, rarely, with other neoplasms. This article describes 4 dogs with marked hypoglycemia associated with smooth muscle tumors (jejunal leiomyoma, gastric leiomyoma and leiomyosarcoma, and splenic leiomyosarcoma). Presenting clinical signs included grand mal seizures, lethargy, weakness, ataxia, and, in 1 dog, polyuria/polydipsia. The serum insulin concentration was low in 1 dog and normal in the other dog evaluated. Immunohistochemical staining for insulin was negative in the 4 tumors; the 3 tumors arising from the stomach and jejunum stained diffusely positive for glucagon. Blood glucose concentrations rapidly returned to normal after complete surgical resection of the tumors, and clinical signs associated with hypoglycemia resolved. Long-term follow-up available in 3 of the 4 dogs found no recurrence of clinical signs related to hypoglycemia at 15, 31, and 38 months after surgery, respectively.