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 angio-genesis by giant cells was observed. The tumors were classified as cardiac angioleiomyoma. Subendocardial multipotential mesench-ymal cells, persistent tissue of the endocardial cushion, or valvular interstitial cells were suspected as the origin. Keywords angioleiomyoma, cardiac neoplasms, cattle, immunohistochemistry, electron microscopy A wider range of primary cardiac tumors has been reported in cattle than in any other animal. Examples include rhabdomyoma,20,21,29 rhabdomyosarcoma,19,24,29,34 periphera