Malignant mesenchymoma with widespread metastasis including bone marrow involvement in a dog

A male castrated Golden Retriever was presented for evaluation of a large mass over the left shoulder extending to the lower part of the neck that had been present for an extended period of time, but had a recent history of rapid growth. Previous aspirates of the mass were consistent with a lipoma. The mass was surgically excised and was diagnosed as an extraskeletal osteosarcoma based on histopathology. After surgery, the dog was initiated on a chemotherapy protocol with carboplatin and metronomic cyclophosphamide. He became neutropenic, anemic, and thrombocytopenic 14 days after the carboplatin treatment was administered. The neutropenia resolved, but the anemia and thrombocytopenia progressed. A bone marrow aspirate revealed erythroid hypoplasia, myeloid hyperplasia with a predominance of early precursors, and a subset of cells that made up 20% of the total population that were reported as bizarre and unclassifiable. These cells were discrete in nature and were thought to be hematopoietic in origin. The dog was euthanized due to deterioration of the clinical condition. On postmortem examination, widespread metastasis involving the lungs, liver, kidney, heart, and bone marrow was found. Histopathology of the tumor lesions determined 2 distinct malignant populations of liposarcoma and osteosarcoma, consistent with malignant mesenchymoma. However, the possibility of 2 separate neoplastic processes cannot be definitively excluded. This is the first report of bone marrow metastasis of a malignant mesenchymoma in a dog.     

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.     

Multicentric osseous lymphoma with spinal extradural involvement in a dog.

Multicentric osseous lymphoma involving the ribs and multiple vertebrae was observed in a 7-year-old Siberian Husky. Extradural spinal cord compression was treated by surgical decompressive hemilaminectomy of L1-2 without noticeable improvement of signs neurologic dysfunction. However, palliation of signs of pain was noticed after irradiation in conjunction with chemotherapy and surgical decompression.     

Polyostotic lymphoma with vertebral involvement and spinal extradural compression in a dog

A 10-year-old, male, mixed-breed dog that developed cervical pain and neurological deficits was diagnosed with primary lymphoma of the second cervical vertebra. The cervical lesion was not surgically resectable. A dorsal cervical hemilaminectomy was performed to provide temporary decompression. The dog had complete pain relief after surgery but was euthanized 6 weeks later with recurrent clinical signs and evidence of lymphoma in the right femur.     

Visceral leishmaniasis with cardiac involvement in a dog: a case report

A dog presented with cutaneous nodules, enlarged lymph nodes and oedema in limbs, face and abdomen. The diagnosis of visceral leishmaniasis was established by identification of Leishmania amastigotes within macrophages from skin and popliteal lymph node biopsies. At necropsy, lesions were found in different organs, but it was particularly striking to observe large areas of pallor in the myocardium. Histological examination revealed an intense chronic inflammatory reaction in many organs, and numerous macrophages were found to contain amastigote forms of Leishmania. The inflammatory reaction was especially severe in the heart, where large areas of the myocardium appeared infiltrated with huge numbers of mononuclear immune cells, causing cardiac muscle atrophy and degeneration. Despite the severe inflammation, the number of parasitized macrophages was low in the myocardium, as revealed by immunohistochemical staining of Leishmania amastigotes. Because cardiac involvement is not usually described in this condition, this dog represents a very rare case of canine visceral leishmaniasis with affection of the myocardium.     

Malignant lymphoma in nasal cavity and paranasal sinuses of a dog

A case of a canine large cell type T-cell lymphoma, with features of high-grade malignancy is described. The tumour was found confined in the nasal cavity and the paranasal sinuses of a crossbred German Shepherd dog. Histological examination revealed the features of a highly malignant large cell lymphoma. Ultrastructurally, the lymphoid tumour cells bore cytoplasmic protrusions that interdigitated tightly. From a panel of tumour markers used, the neoplastic cells were stained only for vimentin. Immunophenotyping of the tumour cells by means of CD3, CD79, kappa-light chains and lambda-light chains detection was undertaken. The tumour stained only for CD3 and was classified as T-cell lymphoma.     

Malignant transformation of an aneurysmal bone cyst in a dog

OBJECTIVE: To report malignant transformation of an aneurysmal bone cyst in a dog. STUDY DESIGN: Case report. SAMPLE POPULATION: Client-owned dog. RESULTS: A 5-year-old male Labrador retriever was diagnosed with an aneurysmal bone cyst of the distal aspect of the right ulna. Surgical curettage resulted in remission of clinical signs for 33 months. Because of recurrence of clinical signs, a distal ulnar ostectomy was performed. Histopathologic examination of the excised specimen revealed a moderately differentiated chondrosarcoma at the level of the bone cyst. Limb function was normal for 17 months until a subcutaneous mass, determined to be a chondrosarcoma, occurred at the level of the shoulder. A right forequarter amputation was performed. CONCLUSIONS: Aneurysmal bone cysts are benign but may be transformed into a malignancy after surgical manipulation. Complete surgical excision should be attempted where possible. In this case, distal ulnar ostectomy was an effective means of preserving limb function and preventing local recurrence of chondrosarcoma.     

Orthovoltage radiotherapy of primary lymphoma of bone in a dog

A 1 1/2-year-old castrated Boxer with a progressive left forelimb lameness of 1 month's duration had a solitary immunoblastic B-cell lymphoma of the proximal portion of the ulna. This primary lymphoma of bone was successively treated with orthovoltage radiation (45 Gy divided into 10 fractions over 22 days). The dog gradually regained normal gait function and did not develop any local recurrence over 34 months. In dogs, primary lymphoma of bone is a rare primary bone tumor, and the ulna is an unusual location for extranodal lymphoma. Local administration of radiation appears to be an effective treatment, allowing retention of normal function.     

Complete atrioventricular block secondary to cardiac lymphoma in a dog

Third degree atrioventricular (AV) block was observed in a patient with a roughly spherical mass measuring approximately 1 × 1 × 1 cm, visible in the basilar portion of the interventricular septum on 2-dimensional transthoracic echocardiographic examination. The patient had a brief history of lethargy and episodic collapse, and the owner elected to euthanize the dog after the mass lesion was discovered. Necropsy revealed multiple masses within the interventricular septum, ventricular free walls and atrial myocardium. The final diagnosis was large cell (T-cell) lymphosarcoma.     

Neurolymphomatosis in a dog with B-cell lymphoma

Lymphoma in the left femoral nerve of a 10-year-old English Cocker Spaniel caused complete paralysis of the affected limb. Neoplastic cells were immunopositive for CD79a and Pax5 and negative for CD3. Neoplastic cells were in multiple lymph nodes and one kidney but spared bone marrow. The clinical and histologic features in this case resemble those of the rare human condition of neurolymphomatosis.     

Malignant seminoma with gross metastases in a dog

A 10-year-old male crossbred dog developed a non-painful unilateral testicular swelling; the other gonad was reduced in size. Both gonads were removed surgically; the larger contained a diffuse seminoma, the smaller atrophic testis contained an interstitial cell adenoma and several intratubular seminomas. Six months after being castrated the dog developed palpable intraabdominal masses. Necropsy revealed gross metastatic malignant seminoma in para-aortic lymph nodes. No histological features were identified to correlate with the malignant behaviour of this usually benign tumour.     

Malignant seminoma with systemic metastases in a dog

A three-year-old male crossbred dog was presented with multiple cutaneous nodules on the dorsum. Unilateral testicular enlargement ensued. Histopathological examination of testicular tissue and the skin lesions revealed a malignant seminoma. Despite the initiation of adjuvant chemotherapy, the dog died three months later due to systemic metastases of the seminoma to the skin, scrotum, eyes, liver, kidney and peritoneum.     

Hepatozoonosis in a dog with skeletal involvement and meningoencephalomyelitis

Abstract: A 15‐month‐old, female mongrel dog was presented with a 6‐week history of inappetence, weight loss, and tetraparesis. Physical examination revealed weakness, poor body condition, mild fever, pale mucous membranes, and diffuse muscle atrophy. The right hind limb was painful and edematous, with large ecchymoses. The femur was irregular on palpation and moderate popliteal lymphadenopathy was evident. Results of a CBC showed severe anemia with mild regeneration, an inflammatory leukogram with 90% of neutrophils parasitized by Hepatozoon sp. gamonts, and moderate thrombocytopenia. A bone marrow aspirate had myeloid hyperplasia and contained a few extracellular Hepatozoon meronts and a few intracellular gamonts within neutrophils. Serum chemistry abnormalities included hypoalbuminemia, hyperglobulinemia, hypoglycemia, hypercalcemia, hyperphosphatemia, and elevated alkaline phosphatase activity. Radiologic findings of the right femur included periosteal bone proliferation and lesions compatible with osteomyelitis. A fine needle aspirate specimen from the bone lesion had neutrophilic inflammation; 36% of the neutrophils contained Hepatozoon gamonts. Results of cerebrospinal fluid analysis included a protein concentration of 37 mg/dL and marked mononuclear pleocytosis (243 cell/μL) with a predominance of lymphocytes. An ELISA was positive for Hepatozoon canis and PCR results with DNA sequencing confirmed infection with this organism. A diagnosis of hepatozoonosis with skeletal involvement and meningoencephalomyelitis was made. The dog recovered almost completely neurologically and had no gamonts in the blood after 60 days of therapy with imidocarb dipropionate and prednisone. This is an unusual case of canine hepatozoonosis involving neurologic signs and a periosteal reaction more typical of H. americanum infection and rarely reported in dogs infected with H. canis.     

Mammary gland carcinoma in a dog with peripheral blood and bone marrow involvement associated with disseminated intravascular coagulation

A 7-year-old female Leonberger dog was referred to the National Veterinary School of Lyon Teaching Hospital with a 2-day history of anorexia and bleeding. A mammary mass had been removed 7 months earlier, but histologic examination was not performed. On physical examination, the dog was depressed and had pale mucous membranes and numerous petechiae and hematomas. Significant laboratory findings were moderate thrombocytopenia, prolonged prothrombin, activated partial thromboplastin, and thrombin times, hypofibrinogenemia, and increased concentration of fibrin(ogen) degradation products. A peripheral blood smear, buffy coat preparation, and bone marrow aspirate contained low numbers of large atypical cells that had moderate nuclear:cytoplasmic ratios, oval nuclei with multiple prominent nuclei, and basophilic cytoplasm with villous projections. A small nodule was found in the left inguinal mammary gland, and a fine-needle aspirate contained cells similar to those in blood and bone marrow. In samples of blood, bone marrow, and the mammary mass, the neoplastic cells were immunoreactive for cytokeratin. The diagnosis was mammary carcinoma with secondary disseminated intravascular coagulation (DIC) and disseminated tumor cells in bone marrow and circulating tumor cells in blood; this diagnosis was not confirmed by histopathologic examination. Owing to clinical deterioration and the poor prognosis, the dog was euthanized and a necropsy was not performed. This is the first report of a canine mammary carcinoma with circulating tumor cells and secondary DIC.     

Protothecosis with ocular involvement in a dog.

An 8 1/2-year-old Collie dog was referred for evaluation of chronic diarrhea as well as sudden blindness and leukokoria of the right eye. An organism morphologically similar to Prototheca sp was recovered from the subretinal fluid and was found at necropsy in the eyes, gastrointestinal tract, lungs, lymph nodes, kidneys, heart, abdominal fat, and omentum.