Primary cardiac rhabdomyosarcoma in a steer

Rhabdomyosarcoma of the tongue in a neonatal calf

A newborn male Holstein calf developed a nodular enlargement at the tip of the tongue. Histopathological examination of the mass revealed predominant proliferating small, round, spindloid or polygonal neoplastic cells with scattered myoblast- and myotube-like cells and multinuclear giant cells. Phosphotungstic acid haematoxylin staining revealed cytoplasmic cross-striations in a few neoplastic cells. Neoplastic cells were immunopositive for vimentin, desmin, myoD1, myogenin, myoglobin and α-smooth muscle actin. The mass was diagnosed as embryonal rhabdomyosarcoma. To the best of our knowledge, this is the first reported case of bovine congenital lingual rhabdomyosarcoma, which is rare in animals.

Primary pharyngeal alveolar rhabdomyosarcoma in an adolescent Japanese black heifer

Alveolar rhabdomyosarcoma (ARMS) is a rare mesenchymal tumor with differentiation toward the skeletal muscle. Although several cases of canine ARMS have been reported in veterinary medicine, only one case of abdominal ARMS has been reported in a cow. A 13-month-old, Japanese black heifer was referred for pus-like nasal discharge. On autopsy, an 11 × 7 × 4.5-cm pedunculated mass closed to the left palatine tonsillar sinus that occupied the laryngopharynx. Histopathological and immunohistochemical analyses indicated that the tumor was a typical ARMS. To the best of our knowledge, this has been the first case of primary pharyngeal ARMS in a Japanese black heifer, which is rare among cows. Nonetheless, its characteristics, including site, age and subtype, are identical to those among humans and dogs.

Alveolar Rhabdomyosarcoma in a Juvenile Labrador Retriever: Case Report and Literature Review

A 7 mo old Labrador retriever presented for evaluation of facial swelling associated with a 5 cm oral mass extending caudally from the upper third premolar on the left side. Cytology revealed an atypical population of round cells of undetermined origin. A diagnosis of alveolar rhabdomyosarcoma (RMS) was reached via histopathology and confirmed with positive immunohistochemical staining for desmin. In humans, RMSs have a well-described round cell cytologic appearance. Few descriptions of veterinary cases of RMS exist. This report describes the cytologic appearance of alveolar RMS in a young dog and both summarizes and compares findings throughout the veterinary and human literature.

Cardiac Angioleiomyoma in 44 Cattle in Japan (1982–2009)

A retrospective study was performed on primary cardiac tumors found in 44 cattle during meat inspection in Japan, using histology, immunohistochemistry, and electron microscopy. The age of affected cattle ranged from 10 to 129 months; 82% were less than 3 years old. In 38 hearts, the tumor was solitary; the remaining 6 hearts had multiple masses. All tumors were subendocardial and involved the papillary muscles and/or cardiac valves. Two histologic patterns were recognized; both included giant cells. Pattern 1 was characterized by interlacing fascicles of spindle-shaped cells; pattern 2 resembled cavernous hemangioma. The 2 patterns coexisted and were linked by transitional zones. Given the immunohistochemical reactivity and ultrastructure, the spindle-shaped cells were identified as smooth muscle cells and the giant cells as endothelial cells. Single cell and multicellular angiogenesis by giant cells was observed. The tumors were classified as cardiac angioleiomyoma. Subendocardial multipotential mesenchymal cells, persistent tissue of the endocardial cushion, or valvular interstitial cells were suspected as the origin.

What is your diagnosis? Perifemoral mass in a cow

A 15-year-old female Simmental cross-breed cow was presented to the Purdue University Veterinary Teaching Hospital for evaluation of a perifemoral soft tissue mass. Impression smears made from an excisional biopsy contained a population of pleomorphic mesenchymal cells with abundant, periodic acid-Schiff-positive (PAS), intracytoplasmic granular material, and rare elongated multinucleated cells consistent with strap-like cells. A second population of small round cells suggestive of lymphocytes or progenitor cells was also noted. A cytologic diagnosis of sarcoma was made, with rhabdomyosarcoma considered most likely based on the large amount of PAS-positive material (presumed to be glycogen) and the rare strap-like cells. Histopathologic sections contained an unencapsulated, densely cellular neoplasm composed of haphazardly arranged highly pleomorphic mesenchymal cells and a few small round cells. The mesenchymal cells were positive for vimentin, non-specific muscle actin, and myoglobin, and negative for phosphotungstic acid-hematoxylin, smooth muscle actin, and desmin. Glycogen granules were confirmed by transmission electron microscopy. A diagnosis of pleomorphic rhabdomyosarcoma was made. While cytologic findings may suggest rhabdomyosarcoma, cytologic features can be highly variable, and a definitive diagnosis usually requires cytochemical and immunohistochemical staining.