Basal Cell Adenocarcinoma of the Sublingual Gland: A Case of an Inadequate FNA Cytology Specimen Rendering Conclusive Diagnosis Difficult

Abstract

A history of a gradual increase in swelling mass was presented in the sublingual gland of a 72-year-old female. The inadequate cytologic specimens retrospectively contained some clusters of three-dimensional monomorphic and round basaloid cells having hyperchromatic small nuclei and scant cytoplasm, along with a small amount of spherical globules of amorphous material and myxoid stroma, adjacent to few squamous metaplastic tumor nests. We first interpreted it as a pleomorphic adenoma, basal cell adenoma (BCA), or adenoid cystic carcinoma (ACC). A tumor extirpation was performed, and gross examination revealed a non-capsulated and ill-defined tumor lesion, looking grayish to yellowish-white, focally associated with fat invasion. On microscopic examination, the tumor was predominantly composed of a proliferation of small to medium-sized mildly atypical epithelial cells having very rare mitoses, often arranged in a cribriform or alveolar growth pattern with peripheral nuclear palisading and scattered squamous differentiation, embedded in a prominent eosinophilic hyaline material. Therefore, we finally made a diagnosis of invasive basal cell adenocarcinoma (BCAC), defined as the malignant counterpart of benign BCA. We should be aware that owing to its characteristic features, cytopathologists might be able to determine correct diagnosis, based on multiple and adequate samplings.