Tracheal Solid Variant of Adenoid Cystic Carcinoma with Basaloid Features: A Case Report and Review of Literature

Abstract Background: Primary tracheal adenoid cystic carcinoma (ACC) is a rare and heterogeneous group of neoplasms arising from the respiratory tract. The solid variant of ACC is a histologically distinct subtype with unfavorable clinical course. We report a case of tracheal ACC with immunohistochemical and molecular analysis together with a review of the literature. Case presentation: A 31-year-old man presented with a neoplasm growing on the lower part of the total tracheal membrane, left side wall and anterior wall. The tumor was obtained via fiberoptic bronchoscopy. Histologically, the tumor is characterized by a predominant compact sheet-like and nested pattern of rounded basaloid cells. Immunohistochemically, the tumor was diffusely positive for CK and CD117. CK7 and CK5/6 was focally positive in the genuine glandular structures. P63 was completely negative in majority of neoplastic cells. Fluorescence in situ hybridization analysis revealed MYB gene rearrangement. The current case showed an almost entirely solid pattern of growth with basaloid features, and was morphologically difficult to distinguish from a variety of other round cell neoplasms. Conclusions: This case report highlights the significance of various histological patterns and diagnostic modalities in making an accurate diagnosis of primary tracheal ACC at an early stage.