Inverted ductal papilloma of minor salivary glands.

Inverted ductal papillomas are rare tumours of minor salivary glands. A case is reported on the lower lip of a 50-year-old man. The tumour showed a characteristic endophytic growth pattern and was composed of bulbous papillary projections of basaloid cells dilating and filling the superficial portion of the excretory duct. Histologically, inverted ductal papillomas resemble the inverted papilloma of the nose and paranasal sinuses, but are completely benign and are not associated with malignant change.