Acinic cell carcinoma of minor salivary gland origin.

We describe a case of acinic cell carcinoma of the right soft palate in a 65-year-old man. The primary symptom was a painless swelling of the palate, which was partially ulcerated with a granulomatous appearance. Ultrastructurally, the tumor cells were mainly composed of differentiated acinuslike cells containing numerous round secretory granules identical to those in normal serous salivary glands. The tumor cells frequently contained numerous long crystalloid structures in the cytoplasm. Furthermore, tumor cells demonstrating degrees of squamous differentiation were present. These cells contained intracytoplasmic keratin filaments and a few keratohyaline granules. They formed a glandular acinar space in direct contact with the typical acinic cells with secretory granules. These observations suggest that acinic tumor cells have a degree of multipotentiality.