Yonago Acta medica 2010;53:065–069
Tubular-Trabecular Type Basal Cell Adenoma of
the Parotid Gland: A Patient Report
Motoki Nakabayashi*†, Kohei Shomori*, Shuichi Kiya‡, Tatsushi Shiomi*, Kanae Nosaka* and Hisao Ito*
*Division of Organ Pathology, Department of Microbiology and Pathology, Tottori University Faculty of Medicine, Yonago 683-8503, †Division of Oral and Maxillofacial Biopathological Surgery, Department of Medicine of Sensory and Motor Organs, Tottori University Faculty of Medicine, Yonago 683-8504 and ‡Clinic of Otorhinolaryngology, Sanin-Rosai Hospital, Yonago 683-8605, Japan
Basal cell adenoma (BCA) is an uncommon benign salivary gland neoplasm that includes isomorphic basaloid cells. We report on a female patient with BCA that developed in the right parotid gland in her 50s. The present patient demonstrated a few tumor nests in the fibrous capsule, and her tumor was larger than usual. These facts made us suspect of malignancy. Histopathologically, the tumor was characterized by multiple duct-like structures and tubular-trabecular masses composed of small isomorphic cells with hyperchromatic, round nuclei and an eosinophilic cytoplasm. It was difficult to determine whether the ductal structures noted in the tumor capsule were invasive. By immunohistochemistry, tumor cells of the tubular nests were positive for cytokeratin 7 and that the outer cells of tubular nests were positive for alpha smooth muscle actin (SMA) and calponin. Tumor cells were immuno-negative for S-100 protein and glial fibrillary acidic protein. The Ki-67 labeling scores of the cells were extremely low (< 1%). We could achieve an accurate diagnosis of BCA by immunohistochemistry with MIB-1 and other markers.
Key words: basal cell adenoma; immunohistochemistry; parotid gland
