A congenital case of intermediate-type fetal rhabdomyoma in an Ardi goat kid
A 5-year-old pregnant Ardi goat presented with dystocia of 36h duration. Vaginal examination showed normal fetal presentation; however, a large neck mass prevented vaginal delivery and cesarean section was performed to deliver the stillborn kid. A well-circumscribed, poorly lobulated subcutaneous mass (12.5cm in diameter) was found on the ventral lateral aspect of the neck. The cut surface was fleshy and tan to pale white in appearance. Histologically, the tumor exhibited moderate to high cellularity and consisted of elongate to ribbon-like myotubes, with many showing differentiation into larger cells having cross-striations. Nuclei were often multiple (2-5+) and peripheral. Neoplastic cells lacked anaplasia and had a low mitotic index (<1 mitosis per 10 fields of 400x magnification). The neoplastic cells had diffuse myoglobin and multifocal desmin immunostaining. The clinical and histopathological features were consistent with a diagnosis of intermediate-type fetal rhabdomyoma, a rare tumor reported in the human literature. This is to our knowledge the first report of intermediate-type fetal rhabdomyoma in the veterinary literature and the first report of dystocia secondary to a congenital, extracardiac rhabdomyoma.