Four sibs in a family on the Isle of Man, two brothers and two sisters ranging in age from 33 to 45 years, presented with low-grade malignant tumors of the submandibular gland in three cases and of the nasal cavities and maxillary sinuses in one. The neoplasms were all of the same histological type, apparently hitherto undescribed, showing well-differentiated neoplastic ducts, surrounded by neoplastic myoepithelial cells, together with sheets of epithelial cells expressing neuroendocrine markers by immunohistochemistry. Cervical neck node metastases have developed in all four cases. In the sib with a primary sinonasal neoplasm, widespread bloodstream metastases also became manifest and a single such metastasis in his brother. All four sibs have severe enamel hypoplasia and the same lesion is present in 5 of their 11 children. In the two male patients, severe sensorineural hearing loss has developed in adult life, unilateral in the left ear in one brother, bilateral in the other. In the brother with bilateral sensorineural hearing loss, magnetic resonance imaging revealed a vestibular schwannoma on the left side, which is currently under treatment. The inherited hearing loss is thought to be unilateral in this case also.