Intraductal carcinoma of the oral cavity: a case report and a reappraisal of the concept of pure ductal carcinoma in situ in salivary duct carcinoma.

The pure in situ form of salivary duct carcinoma, also known as intraductal carcinoma, is very rare, and its existence is controversial. We describe a case arising from the minor salivary glands. The patient was a 44-year-old woman who presented with a painless mass in the buccal mucosa. On microscopic examination, the tumor comprised crowded and smooth-contoured epithelial units exhibiting a fenestrated or cribriform pattern, occasionally punctuated by comedonecrosis. An attenuated layer of myoepithelial cells could be demonstrated around all the islands by immunostaining for p63 and actin, indicating absence of an invasive component. The patient remained well following local excision. This case, together with other reported cases, suggests that intraductal carcinoma is a distinct entity. It may represent the preinvasive phase of some invasive salivary duct carcinomas but by itself is nonmetastasizing and associated with an excellent prognosis.