Clinical behavior of intraocular teratoid medulloepithelioma in two‐related Quarter Horses

The objective of this paper is to describe clinical behavior, histopathologic features, and immunohistochemical staining of two‐related horses with intraocular teratoid medulloepithelioma. Two‐related Quarter Horses with similar intraocular masses presented to the UF‐CVM Comparative Ophthalmology Service for evaluation and treatment. The first horse, a 3‐year‐old gelding, had glaucoma and a cyst‐like mass in the anterior chamber. Enucleation was performed. Histopathology revealed a teratoid medulloepithelioma. The tumor was considered to be completely excised. Fifteen months later, the gelding presented with swelling of the enucleated orbit and local lymph nodes with deformation of the skull. Cytology revealed neuroectodermal neoplastic cells. Necropsy confirmed tumor metastasis. Six weeks later, a 9‐year‐old mare, a full sibling to the gelding, presented for examination. An infiltrative mass of the iris and ciliary body was found that extended into the anterior, posterior, and vitreal chambers. Uveitis was present, but secondary glaucoma was not noted. Enucleation was performed and the histopathologic diagnosis was also teratoid medulloepithelioma. The mare has had no recurrence to date, 2 years following enucleation. Metastasis of intraocular teratoid medulloepithelioma is possible. Staging is recommended in cases where the diagnosis of teratoid medulloepithelioma is confirmed. Surveillance of full siblings is recommended until more information regarding etiology is known.     

Malignant Sertoli cell tumor in the retained abdominal testis of a unilaterally cryptorchid horse

A 13-year-old Morgan gelding was evaluated because of a mass in the caudal region of the abdomen. The horse had been presumed to be a gelding, but necropsy findings revealed a retained testis in the right retroperitoneal space. Histologically, the retained testis contained neoplastic cells; metastases were identified in the liver, spleen, lungs, and sublumbar lymph nodes. Immunohistochemical examination of the testis and metastatic tissues confirmed the diagnosis of malignant Sertoli cell tumor. Testicular neoplasms are infrequently reported in stallions. Seminomas are most commonly reported, whereas Sertoli cell tumors are considered to be rare. Typical biological behavior of Sertoli cell tumors in horses is unknown. To the authors' knowledge, there have been 2 reports of Sertoli cell tumors in horses; the tumors developed in descended testes, and 1 tumor was malignant.     

Malignant teratoid medulloepithelioma in a llama

A lesion was identified in the eye of a juvenile llama, and preliminary clinical findings included anterior uveitis and an exudative retinal detachment suggestive of infectious disease. However, histopathologic evaluation of the enucleated globe revealed an intraocular neoplasm composed of primitive neuroepithelium forming ribbons, cords, and rosettes, heteroplastic elements including spindle cells in a loose myxomatous matrix, and islands of well-differentiated hyaline cartilage. Immunohistochemically, neoplastic cells were positive for vimentin and neuron-specific enolase. Spindle cells were multifocally positive for desmin and muscle specific actin, indicating differentiation towards myofibers. These findings are consistent with a diagnosis of malignant teratoid medulloepithelioma, an extremely rare ocular neoplasm that affects children and young animals.     

Of all the nerve! A subcutaneous forelimb mass on a cat

A 16-year-old, male, neutered cat had a 2.5 X 1.5 cm mass on the medial aspect of the right carpus. Cytologic examination of a fine-needle aspirate of the mass indicated a markedly pleomorphic population of plasmacytoid to histiocytic-appearing cells. The cytologic diagnosis was malignant neoplasia of probable mesenchymal or round cell origin. The right forelimb was surgically removed and the scapular, axillary, and prescapular lymph nodes were excised. Malignant fibrous histiocytoma was tentatively diagnosed histologically; however, the tumor cells subsequently were found to be negative for histiocytic (MAC 387, antitrypsin), T-cell (CD3), and B-lymphocyte (immunoglobulin light chains, Ly 5/CD45R) markers, and positive for glial fibrillary acidic protein, vimentin, and S-100. Based on the immunohistochemical results, the diagnosis was modified to malignant peripheral nerve sheath tumor (PNST). Six months after surgery, the cat was reported to be well and had no evidence of metastasis. PNSTs are rare tumors in cats, and are considered as synonymous with schwannomas, neurofibrosarcomas, and hemangiopericytomas. In this cat, the plasmacytoid and pleomorphic appearance of the PNSTcells in cytologic and histologic specimens was unusual, and made it difficult to reach an accurate diagnosis without immunocytochemistry.     

Neoplastic melanocytic pleural effusion in a Portuguese water dog

A 9-year-old castrated male Portuguese water dog was presented following incomplete excision of a malignant melanoma at the left lip commissure by the referring veterinarian. Physical examination was otherwise unremarkable. The patient was staged using thoracic radiographs, abdominal ultrasound, and fine-needle aspirates of the mandibular lymph nodes and spleen. Given the absence of any definitive evidence of metastasis, the malignant melanoma was surgically completely removed. The dog then received four melanoma vaccine doses as an adjuvant therapy and remained clinically healthy for more than 3 months after the last immunization. However, 232 days after the initial discovery of the lip mass, the dog was euthanized due to deterioration and a poor prognosis based on the presence of lung metastases and neoplastic melanocytic pleural effusion. The latter has been rarely reported in dogs, despite the high prevalence of oral malignant melanomas and the tendency of these tumors to metastasize to the lungs.     

Association between lymph node size and metastasis in dogs with oral malignant melanoma: 100 cases (1987-2001)

OBJECTIVE: To determine the association between lymph node size and metastasis and to assess measurement of lymph node size as an accurate and reliable means of tumor staging in dogs with oral malignant melanoma. DESIGN: Retrospective study. ANIMALS: 100 dogs with histologically confirmed oral malignant melanoma. PROCEDURE: Clinical records for dogs with oral malignant melanoma were reviewed. Data regarding size and results of cytologic or histologic examination of lymph nodes were evaluated. The association between lymph node size and metastasis was determined. RESULTS: Forty-seven (47%) dogs, of which 23 (49%) had enlarged mandibular lymph nodes, had no cytologic or histologic evidence of metastasis. Of 53 (53%) dogs with cytologic or histologic evidence of mandibular lymph node metastasis, 37 (70%) had enlarged mandibular lymph nodes, and 16 (30%) had mandibular lymph nodes of normal size. Overall, 16 of the 40 (40%) dogs with normal-sized lymph nodes had microscopic evidence of metastatic disease. Sensitivity and specificity of lymph node size as a predictor of metastasis were 70 and 51%, respectively, and the positive and negative predictive values were 62 and 60%, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: Although a significant relationship was identified between lymph node size and metastasis to the lymph node, this association did not appear strong enough to be clinically relevant. Results suggest that lymph node size alone is insufficient for accurate clinical staging of oral malignant melanoma in dogs; cytologic or histologic examination of regional lymph nodes should routinely be performed, regardless of size of those nodes.     

Cutaneous T-cell-rich B-cell lymphoma in a horse

Cutaneous malignant lymphomas are rare in horses and comprise predominantly T-cell-rich B-cell lymphomas. They are characterized by multiple tumour nodules affecting predominantly female horses with a survival rate of months to years. At the final stage, metastases to regional lymph nodes occur, whereas widespread organ involvement is rarely reported. In this case report, a cutaneous T-cell-rich B-cell lymphoma in a 7-year-old standardbred gelding with metastases is described. Clinically, multiple cutaneous and subcutaneous nodules, enlarged superficial lymph nodes, rapid weight loss, and ventral oedema were observed. In addition to the clinical findings, necropsy revealed tumour infiltration in multiple body lymph nodes, a solitary pleural mass, and few pulmonary and intestinal tumour nodules. Microscopically, all neoplasms were composed of a densely packed cell population consisting of large lymphoblastic cells expressing CD79a, and numerous small, round, CD3-positive T lymphocytes. With respect to these findings the diagnosis of a cutaneous T-cell-rich B-cell lymphoma with metastases was made.     

Malignant mixed tumor in the salivary gland of a cat

The presence of a malignant mixed tumor, also known as a carcinosarcoma, in the salivary gland is very rare. Such tumors, which are typically aggressive, are characterized by the presence of carcinomatous and sarcomatous components. A 9-year-old neutered female domestic short-haired cat presented with swelling in the right mandibular lesion that had rapidly enlarged over the previous 3 weeks. Physical examination revealed a large, fluctuated and painless subcutaneous swelling that was associated with a firm mass. Radiographs of the head revealed a soft-tissue density that involved faint circular calcific opacity. Contrast-enhanced computed tomography revealed that the peripheral capsulated cystic area had a contrast enhanced region without bone lysis. The cat received a total excision of the mass and postoperative radiotherapy. Histopathological analysis of the mass revealed that it was a malignant mixed tumor. Metastasis to the lung was discovered 7 weeks later, at which time treatment was stopped.     

Immunohistochemical characterization of a malignant intraocular teratoid medulloepithelioma in a cockatiel

A 3-year-old cockatiel was presented for evaluation of a buphthalmic right eye (OD). The history included a traumatic event 5 months prior to presentation, and the referring veterinarian diagnosed cataract and secondary glaucoma. Computed tomography of the bird's orbital region revealed a large right orbital soft tissue mass that extended lateral to the orbital rim with obliteration of the globe without bone involvement. There was also no evidence of metastatic disease within the lungs or any abnormalities within the celomic cavity, therefore enucleation was recommended to achieve a histopathologic diagnosis and prognosis, and to palliate the clinical signs. Final diagnosis was malignant intraocular teratoid medulloepithelioma.     

Malignant teratoid medulloepithelioma with brain and kidney involvement in a dog

ANIMAL STUDIED: A tumor of the left eye with involvement of the brain and kidney was diagnosed in a 4-year-old Neapolitan mastiff. PROCEDURE: The dog presented with acute glaucoma of the left eye. Peripheral corneal vascularization and severe corneal edema obscured examination of deeper structures. Because of concurrent progressive neurologic signs the dog was euthanized and a postmortem examination was performed. The eyes, brain and samples from the lung, heart, liver and kidneys were fixed in 4% neutral buffered formalin and embedded in paraffin wax. Sections were examined by light microscopy including histochemical and immunohistochemical staining. RESULTS: The ocular tumor originated from the ciliary body and was composed of small islets and cords of poorly differentiated, oval to polyhedral cells surrounded by abundant ground substance. Areas with chondroid differentiation were observed. Rosettes were not found. Metastases with the same morphology were present in the brain and in one kidney. CONCLUSION: An intraocular malignant teratoid medulloepithelioma with metastases to the brain and kidney is presented.     

Complex mammary carcinoma with metastases to lymph nodes,subcutaneous tissue,and multiple joints in a dog

An 8‐year‐old, intact female, mixed‐breed dog presented to the Oklahoma State University Boren Veterinary Medical Teaching Hospital for evaluation of progressive lameness and joint effusion of multiple joints. Physical examination revealed joint effusion of the elbow, hock, and stifle joints bilaterally, enlarged left axillary and right popliteal lymph nodes, a subcutaneous mass over the left elbow, and a subcutaneous mass involving the left second and third mammary glands. Cytologic examination of the mammary mass, enlarged lymph nodes, and joint fluid from most affected joints revealed a monomorphic population of loosely cohesive neoplastic epithelial cells. The patient was humanely euthanized, and subsequent necropsy with histopathologic examination revealed a complex mammary carcinoma with metastases to enlarged lymph nodes, subcutaneous tissue over the left elbow, and the synovium of multiple joints. Immunohistochemical stains were performed and showed diffusely positive pan cytokeratin, CK8/18, and CK19 staining in the neoplastic luminal epithelial cells of the mammary carcinoma, synovium, and lymph nodes, and showed diffusely positive vimentin staining of the myoepithelial cells. Myoepithelial calponin positivity was diffuse in the mammary mass and lymph nodes but minimal in the synovium. Only the mammary mass showed p63 positivity. Metastatic mammary neoplasia is relatively common in dogs; however, metastasis to the synovium has only been reported once previously in the literature. This is the first case utilizing immunohistochemistry for confirmation and characterization of metastases.     

Presumed post‐traumatic ocular chondrosarcoma with intrathoracic metastases in a cat

An indoor‐only, 5‐year‐old, spayed female domestic shorthair cat presented for an ophthalmic examination of the left eye. An intraocular tumor with secondary glaucoma and blindness was diagnosed; the globe was enucleated and sent for histopathological examination. Gross examination revealed a solid white mass filling the entire vitreous space and replacing the iris and ciliary body. The lens and retina appeared to be similarly replaced by the neoplasm. Histological examination revealed a complete loss of the internal ocular structures, with a ruptured capsule as the only remnant of the lens within an extensive malignant mesenchymal neoplastic cell proliferation. The cells were polygonal, with well‐defined cytoplasmic borders and abundant weakly basophilic cytoplasm, embedded within the islands of chondroid matrix. No neoplastic invasion of the sclera was apparent. The animal died 6 months after the enucleation due to respiratory distress. Gross examination revealed numerous firm, white to tan nodular masses with smooth to mildly irregular surfaces dispersed throughout the parietal pleura, thoracic surface of the diaphragm, tracheobronchial and mediastinal lymph nodes, pericardium, and lungs. On cross‐section, the neoplastic nodules were solid and variably translucent, resembling hyaline cartilage. Histologically, these nodules were similar to the neoplasm identified earlier in the left globe. Metastasis of post‐traumatic ocular chondrosarcoma has not yet been described in cats. This is therefore believed to be the first report of metastases of this type of neoplasm in cats. This case adds to the limited set of data on the outcome of this type of tumor.     

Unusual metastasis of malignant aortic body tumor to multiple bones in a dog

Unusual metastasis of malignant aortic body tumor to multiple bones was detected in a 5-year-old female English Setter dog. Radiographs exhibited an abnormal mass in the base of heart and osteolytic lesions in the bodies of T11 and L2 vertebrates, body of right femur, right proximal humoral epiphysis and infraspinous fossa near to the neck of right scapula. At necropsy, multiple tumor masses of various sizes were observed also in the bones as well as the heart base and tracheobronchial lymph node. Tumor masses of L2 and T11 protruded into the vertebral canal and compressed corresponding sites of spinal cord, leading to paraplegia. Histopathologically, the tumor cells, arranged in sheets or nests, were polyhedral, lightly eosinophilic, finely granular cytoplasm with mostly round to oval nucleus and had scattered bizarre giant cells. Ultrastructural study revealed the characteristic findings that tumor cells contained a large number of small, electron-dense, membrane-limited secretory granules in cytoplasm. This is thought to be an extremely rare case having multiple bone metastases of a malignant aortic body tumor.     

Ocular manifestations of a metastatic adenocarcinoma in a horse

A 10‐year‐old German Warmblood gelding was referred to the Equine Department of the Vetsuisse Faculty, University of Zurich, Switzerland, for an iris mass OD, lethargy, intermittent fever, and coughing. Ophthalmic examination revealed a 7 × 9 mm raised, fleshy, whitish to pinkish, vascularized iris mass at the 2 o`clock position OD. Fundic examination showed multifocal round, brown to black, slightly raised lesions with indistinct margins and a surrounding hyperreflective zone OU. Physical examination revealed a temperature of 39.2 °C, sinus tachycardia, preputial and ventral edema, and an enlarged right mandibular lymph node. Results of a complete blood count and plasma biochemical profile showed mild anemia, leukocytosis, and thrombocytopenia. Severe splenopathy, moderate splenomegaly, and severe pulmonary pathology with nodules and large areas of consolidated lung parenchyma were observed on abdominal ultrasound and thoracic radiographs, respectively. Fine needle aspirates of the enlarged mandibular lymph node showed malignant epithelial neoplastic cells. The horse was euthanized because of the poor prognosis and subsequently underwent postmortem examination. Macroscopic necropsy and histopathology revealed an adenocarcinoma of suspected pulmonary origin with involvement of eyes, heart, liver, kidneys, spleen, diaphragm, skeletal muscles, mandibular, pulmonary, and internal iliac lymph nodes. Metastatic adenocarcinoma should be considered as a differential diagnosis in horses with iris masses, multifocal chorioretinal infiltrates, and clinical signs that conform to a paraneoplastic syndrome.     

Surgical treatment of a mandibular ameloblastic carcinoma with metastases to the mandibular lymph nodes in a pony

A 4-year-old Connemara filly was presented with a rapidly growing oral mass on the right rostrolateral mandible and a right mandibular lymphadenopathy. Radiographs of the rostral mandible revealed a lytic, infiltrative mass consistent with soft tissue and mineralised material, and displacement of tooth 403. A biopsy showed characteristic histopathological features of an ameloblastic carcinoma. Subsequent FNA of the right abnormally firm and enlarged mandibular lymph node confirmed the metastatic spread. Computed tomography of the head was performed for surgical planning, including sentinel lymph node mapping to rule out other lymph node involvement. An aggressive lesion, consistent with soft tissue of the rostral right mandible was identified with intralesional contrast injection showing drainage of contrast within the right mandibular lymph nodes (Sentinel node). Based on the infiltrative and destructive nature reported in ameloblastic carcinoma in humans, a rostral mandibulectomy was performed, along with complete mandibular lymphadenectomy. The horse recovered uneventfully from surgery. In the early post-operative period marked lymphoedema of the ventral mandibular region was observed, which resolved 4–5 days post-operatively. Optimal cosmesis was maintained post-operatively, and no recurrence has been observed to date – 12 months post-surgery.     

Carcinoma of the submandibular salivary glands with multiple metastases in a cat

A 9-year-old neutered male domestic shorthair cat was presented because of coughing, dysphagia, and prostration. Examination revealed firm bilateral anterocervical swellings extensively adhered to the surrounding tissues. Anisocoria with left-side miosis was also evident. X-ray and ultrasound examinations along with a fine-needle aspiration biopsy were performed. Slides were stained with May-Grünwald Giemsa, and a diagnosis of salivary gland carcinoma was made. At surgery, the tumor was found to involve both submandibular salivary glands as well as adjacent lymph nodes and surrounding tissues. The cat was euthanized and necropsy was performed. The majority of tissues and organs examined histologically, including mandibular and retropharyngeal lymph nodes, soft palate, laryngopharynx and lungs, contained neoplastic cells whose appearance was consistent with adenocarcinoma. Bilateral salivary adenocarcinoma has not previously been reported in cats, and extensive metastases are rare.     

Metastatic pancreatic polypeptide‐secreting islet cell tumor in a dog

Abstract: A 14‐year‐old female spayed Golden Retriever was presented to the University of Florida's Veterinary Medical Center with history of lymphoplasmacytic gastroenteritis, intermittent vomiting, watery diarrhea, and weight loss for over a year. CBC, biochemical profile, and urinalysis were within reference intervals. Abdominal ultrasonographic examination revealed mesenteric and jejunal lymphadenopathy and hyperechoic hepatic nodules. Cytologic examination of the enlarged lymph nodes revealed loosely cohesive cells with moderate nuclear pleomorphism and rare punctate eosinophilic cytoplasmic granules. The cytologic interpretation was metastatic neuroendocrine neoplasia. On surgical exploration, a mass was detected in the right lobe of the pancreas. Histologic evaluation determined the mass to be an islet cell tumor. Approximately 98% of cells were positive by immunolabeling for pancreatic polypeptide (PP), and only rare cells were positive for insulin or somatostatin. All cells were negative for glucagon, gastrin, vasoactive intestinal polypeptide, protein gene product 9.5, synaptophysin, and chromogranins A and B. Pancreatic tumors that primarily produce PP are rare in dogs, and this is the first report of both the cytologic and histologic features of an islet cell tumor predominantly secreting PP. Clinical signs for these tumors are typically absent or nonspecific; signs may include watery diarrhea, as noted in this dog, although the diarrhea may have resulted from lymphoplasmacytic gastroenteritis. Additional case studies are needed to further characterize the cytomorphologic features and clinical presentation of PP‐secreting islet cell tumor, or polypeptidoma, in dogs.     

B‐cell lymphoma with Mott cell differentiation in a cat

A 12‐year‐old, male castrated Domestic Shorthair cat was presented to Animal Medical Center of Gifu Univeristy with anorexia and vomiting. Physical examination revealed an enlarged left tonsil and right mandibular lymph node (approximately 2–3× the normal size), and a submucosal mass on the right side of the epiglottis (1.5 × 2.0 cm). On computed tomography images, an enlarged left tonsil, and enlarged right mandibular, right pharyngeal, and left and right cervical lymph nodes were observed. Cytologic examination of smears of tonsil and lymph nodes revealed numerous medium‐ to large‐sized neoplastic lymphoid cells, approximately half of which contained one or several light‐blue homogenous globoid cytoplasmic inclusions (5–10 μm), which stained magenta with periodic acid–Schiff (PAS) stain. Histopathologic examination of the left tonsil revealed diffuse proliferation of medium‐ to large‐sized neoplastic lymphoid cells effacing the original lymphoid architecture. Half of the cells contained one or several eosinophilic globoid cytoplasmic inclusions, which stained magenta with PAS and showed positive immunohistochemical reactions for immunoglobulin M (IgM) and λ light chain. Neoplastic lymphoid cells were also CD20⁺, Pax5⁺, and MUM1⁺, and CD3^?. Thus, the neoplastic lymphoid cells expressed a B‐cell immunophenotype, and the globoid cytoplasmic inclusions represented an aberrant IgM λ light chain accumulation, similar to Russell bodies. B‐cell lymphoma with Mott cell differentiation was diagnosed based on cytologic, histopathologic, and immunohistochemical features. This is the first report of B‐cell lymphoma with Mott cell differentiation in a cat.     

Non-gestational malignant placental site trophoblastic tumor of the ovary in a 4-year-old rhesus monkey

We report a case of ovarian malignant intermediate-type trophoblastic tumor in a clinically normal, nonpregnant 4-year-old rhesus monkey (Macaca mulatta). A large solid lobulated mass replaced the right ovary and filled the pelvis. Multiple metastases were observed within the lungs and the liver. The tumor was histologically identified as predominantly composed of intermediate trophoblastic cells, without prominent hemorrhages and the classic bilaminar pattern of cyto- and syncytiotrophoblastic cells characteristic of choriocarcinoma. Immunohistochemical analysis showed the presence of placental lactogen hormone in many tumor cells and chorionic gonadotropin in a few multinucleated cells consistent with syncytiotrophoblastic differentiation. No other germ cell differentiation was identified in the pelvis mass nor in the metastases. In the absence of previous and present pregnancy, this neoplasm has to be considered as a nongestational malignant placental site trophoblastic tumor of the ovary.