Pediatric Benign Tumors With a Skeletal Muscle Component: Myogenin Expression, Diagnostic Pitfalls, and New Molecular Insights

Fetal rhabdomyoma in a Thoroughbred filly

A newborn Thoroughbred filly presented with a large mass located on the ventro-rostral aspect of the mandible. The mass was surgically removed under general anaesthesia. Upon gross examination, the mass was well circumscribed with a heterogeneous lobulated appearance. The results of histopathology and immunohistochemistry were consistent with a diagnosis of congenital fetal rhabdomyoma. On follow-up at six months post-surgical excision, no abnormalities were noted on clinical examination.