Atypical fibromas are characteristically composed of proliferating GL cells of the skin. Atypical fibromas are reported predominantly in male Djungarian hamsters and are seldom seen in females, because they are androgen-dependent tumors.1 Kashida et al.10 suggested that GL cells in Djungarian hamsters are derived from intrinsic undifferentiated mesenchymal cells in the dermis or subcutaneous adipose tissue. Cooper et al.4 reported fibromas and fibrosarcomas in laboratory Djungarian hamsters, but whether they were atypical fibromas is unknown. There are no reports about the occurrence of atypical fibromas in domestic or laboratory Syrian hamsters. In our study, all atypical fibromas occurred in males, which confirmed the reported sex predilection. Neoplasms composed of GL cells with malignant findings were provisionally diagnosed as atypical fibrosarcomas. According to Baba et al.,1 predilection sites of atypical fibromas are the thoracoabdominal area. In our study, anatomical localization of most atypical fibromas and immunohistochemical characteristics were consistent with previous reports.
Veterinary Sciences 15 out of 129 | Pathology 39 out of 76