Mucinous cystadenocarcinoma of a minor salivary gland in the upper lip: case report.

Mucinous cystadenocarcinoma of the salivary gland is a rare entity that has only recently been described. This lesion was included in the 1991 World Health Organization Classification as "papillary cystadenocarcinoma," and that same year the United States Armed Forces Institute of Pathology classified it as "cystadenocarcinoma with or without a papillary component." Only a small proportion of salivary gland tumors are adenocarcinomas. Most mucinous cystadenocarcinomas affect the major salivary glands, particularly the parotid. These are low-grade malignancies, and most that occur in the minor salivary glands show very little aggressive behavior. These tumors are histologically similar to adenocarcinomas of the gastrointestinal tract. It is often difficult to differentiate them from other neoplasms. The differential diagnosis includes mucoepidermoid carcinoma, acinic cell carcinoma, salivary duct carcinoma, nasal adenocarcinoma, and metastatic carcinoma. This report describes the case of an 80-year-old man who presented with a painless swelling in his right upper lip that had been present for 1 month. Fine-needle aspiration biopsy of the lesion revealed inflammatory cells without an epithelial component. The treatment was wide excision, and there was no recurrence during 6 months of follow-up. The pathological diagnosis was low-grade mucinous cystadenocarcinoma of a minor salivary gland.