Leiomyosarcoma of soft tissue in a cow

Subcutaneous leiomyosarcoma in a cynomolgus macaque (Macaca fascicularis)

Leiomyosarcoma, a malignant tumour originating from smooth muscle cells, has rarely been documented in non-human primates. In this case study, a 7-year-old female cynomolgus macaque (Macaca fascicularis) presented with a rapidly growing mass overlying the left elbow joint. Radiographs indicated the presence of a soft tissue neoplasm without any associated bone involvement. The mass was surgically resected. Histological and immunohistochemical analyses revealed spindle-shaped cells with eosinophilic cytoplasm that resembled smooth muscle cells, exhibiting positive immunoreactions for vimentin, desmin and smooth muscle actin and a negative reaction for pan-cytokeratin. This is the first reported case of subcutaneous leiomyosarcoma in a cynomolgus macaque and provides important insights into the incidence and characteristics of this condition in this species.

Epithelioid Leiomyosarcoma in the Visceral Peritoneum of an American Badger (Taxidea Taxus)

A 12-year-old female American badger was presented to the Taipei city zoo veterinary ward with anorexia and weakness. Treatments were ineffective, and the badger died of chronic interstitial nephritis and uremia. At necropsy, numerous firm white nodules, measuring 0.5–2.0 cm, were present on the surface of the liver, stomach, spleen, small intestine, pancreas, and diaphragm. Most nodules were encapsulated and well demarcated from the organs to which they were attached. A poorly demarcated mass, measuring 0.5 cm in diameter, had invaded the hepatic parenchyma and appeared to be the origin of all the nodules derived by transcavitary implantation. Histologically, the nodules contained primarily oval or spindle-shaped cells, typical of smooth muscle cells, forming alternating bundles attached to the surface of the various organs. In some nodules, aggregates of individual polyhedral to round cells with round to oval centrally located nuclei and abundant eosinophilic cytoplasm, typical of smooth muscle origin, were noted. Zones of subcapsular necrosis and multifocal necrosis were also observed in some nodules. Tumor cells stained positively for α-smooth muscle actin and vimentin and negatively for desmin, cytokeratin, estrogen, and progesterone receptors. This tumor is similar to but distinguishable from the “disseminated peritoneal leiomyomatosis (DPL)” found in women.

Primary subcutaneous leiomyosarcoma of the hamster hind leg

We report the first case of a primary subcutaneous leiomyosarcoma that originated in the hind leg of a hamster and metastasized to the bone marrow, lung and diaphragm. A 10-month-old female Syrian golden hamster was presented with a large, firm, white subcutaneous mass in the right hind leg. The tumor invaded into the bone marrow and small nodules were also present in the lung and diaphragm; however, no tumor masses were found in the visceral organs. Histologically, the tumors were spindle cell sarcomas, composed of densely packed pleomorphic spindle cells with oval to elongate nuclei and moderate amounts of eosinophilic cytoplasm. Immunohistochemically, the neoplastic cells were positive for vimentin, desmin, and smooth muscle actin, but negative for alpha-sarcomeric actin and S-100. Thus, the diagnosis was primary leiomyosarcoma of the hind leg with metastasis to the bone marrow, lung and diaphragm. To the best of our knowledge, this is the first report of spontaneous primary subcutaneous leiomyosarcoma of the hind leg with distant metastasis in laboratory animals.

Microchip-associated leiomyosarcoma in an Egyptian fruit bat (Rousettus aegyptiacus)

Microchips are commonly used in companion, research, and zoo animal medicine for easy, reliable, and cost-effective identification with relatively low risk of side effects. This report describes development of a metastatic leiomyosarcoma associated with a microchip in an Egyptian fruit bat (Rousettus aegyptiacus).

Spontaneous Uterine Leiomyosarcoma in a Golden Hamster (Mesocrietus auratus)

Uterine leiomyosarcoma occurring spontaneously in a domestic golden hamster was examined histologically and immunohistochemically. The histological findings for this tumour were similar to those for leiomyosarcomas described in other species. Immunohistochemical examination demonstrated the positivity of neoplastic cells with alpha-smooth muscle actin and desmin. From the results mentioned above, the tumour of this case was revealed to be of smooth muscle origin. To our knowledge, this is the first report of a uterine leiomyosarcoma in domestic golden hamsters.

Cutaneous smooth muscle tumors in the dog and cat

Cutaneous smooth muscle tumors may arise from arrector pili muscles and from smooth muscles of the dermal vasculature. This report describes histologic and immunohistochemical features of eight arrector pili hamartomas in 8 dogs, 15 piloleiomyomas in 10 dogs and 3 cats, 10 piloleiomyosarcomas in 9 dogs and 1 cat, 1 angioleiomyoma in 1 cat, and 9 angioleiomyosarcomas in 6 dogs and 3 cats. Hamartomas and tumors arising from arrector pili muscles preferentially originated from the dorsal trunk. 5/5 (100%) arrector pili hamartomas, 10/12 (83%) piloleiomyomas, 4/5 (80%) piloleiomyosarcomas, 1/1 (100%) angioleiomyoma, and 6/7 (86%) angioleiomyosarcomas were positive for smooth muscle actin. 5/5 (100%) arrector pili hamartomas, 10/12 (83%) piloleiomyomas, 4/5 (80%) piloleiomyosarcomas, 1/1 (100%) angioleiomyoma, and 1/7 (14%) angioleiomyosarcomas were positive for desmin. Two incompletely excised canine angioleiomyosarcomas recurred locally. Metastases were not reported.

Myofibroblastic sarcoma of the pleura in a pig

An intrathoracic sarcoma from a 7-month-old female pig was studied by light and electron microscopy and immunohistochemistry. The tumor tissue of varied cell density consisted chiefly of spindle-shaped cells, some of which grew around blood vessels in a concentric fashion. Many tumor cells were positive for alpha smooth muscle actin and not for desmin, though some cells were reactive for both antigens. A majority of tumor cells had ultrastructural features characteristic of myofibroblasts, but a few cells resembled vascular smooth muscle cells in the synthetic state. This neoplasm may have arisen from vascular smooth muscle with features indicating a transition to myofibroblasts.

Myofibroblastoma of the neck in a heifer

A 1.5-year-old Holstein heifer had a subcutaneous tumor mass (20 cm diameter) on the ventral portion of the neck, and the tumor was diagnosed as a locally invasive myofibroblastoma. It consisted of moderately cellular fibrous tissue, and the interlobular septum of the thymus was invaded by tumor cells. The neoplastic cells were positive for alpha smooth muscle actin and vimentin, but not for desmin. Electron microscopy disclosed the presence of moderately developed rough endoplasmic reticulum and microfilaments with focal densities.

Differentiated embryonal rhabdomyosarcoma in a cow

An embryonal rhabdomyosarcoma was found in the pleura of a 2-year-old Holstein cow after first delivery. The most predominant cells in the tumor were relatively small in size, but considerable numbers of more differentiated cells of larger sizes mingled with the small cells. The most differentiated cells were characterized by multinucleation, abundant cytoplasm containing cross-striated fibrils, intense immunoreactivity for desmin, and weak or negative reactivity for vimentin. Such cells, lacking mitotic activity and displaying weak or no reactivity for proliferating cell nuclear antigen, were considered to be malignant counterparts of myotubes or muscle fibers. This neoplasm seems to follow normal skeletal muscle embryogenesis, and to be capable of differentiation into the final stage of muscle development.

Haemangiopericytoma in a calf

After castration, a Japanese Black male calf developed subcutaneous tumours near the scrotum. They were surgically excised, and no recurrence was detected two years after surgery. The tumours were characterised by neoplastic cells concentrically arranged around blood vessels of various sizes. The neoplastic cells contained many cytofilaments, and the majority of the cells expressed smooth muscle actin, but focal densities were not found. On the basis of the immunohistochemical and ultrastructural features, the tumours were considered to be of pericyte origin.