Diagnostic and therapeutic approach to sialoblastoma: report of a case.

The natural history of a rare parotid tumor, the sialoblastoma (embryoma) is reported. It is a blastematous neoplasm said to recapitulate the epithelial differentiation of a gland at various stages of development. The tumor grew in a period of 5 years (from shortly after birth until it was excised) to a firm asymptomatic mass measuring 5 cm in greatest diameter. With a diagnosis of adenoid cystic carcinoma (a common misdiagnosis), the patient was referred to the reporting institution, where the diagnosis was revised. Five months later, completion parotidectomy for presumed recurrence failed to demonstrate residual tumor. One year later, the patient appears to be free of disease. The authors propose that sialoblastomas should be regarded neither as benign nor malignant, but as one single disease with local infiltrative potential. Based on this concept, sialoblastomas can be treated with early conservative surgery alone, provided that free margins are obtained.