A Case of Solid Variant of Adenoid Cystic Carcinoma from Trachea: A Case Report and Review of Literature

INTRODUCTION: 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 an unfavorable clinical course. We report on a case of tracheal ACC with immunohistochemical and molecular analysis together with a review of the literature. CASE REPORT: We observed a case in which a 31-year-old male presented with a neoplasm bulging into the lumen and caused symptoms of tracheal obstruction and even hemoptysis. Cytological smears of an endobronchial fine needle aspiration revealed aggregates of basaloid cells with small to medium size, scant cytoplasm, and evenly hyperchromatic nuclei. 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 were focally positive in the genuine glandular structures. P63 was completely negative in the majority of neoplastic cells. Fluorescence in situ hybridization analysis revealed MYB gene rearrangement. CONCLUSION: The solid variant of ACC from trachea is rare and hence poses diagnostic difficulty. Computed tomography (CT) scan and bronchoscopy help assess the extent of the disease. Histological features combined with immunophenotypic and molecular analysis aid in distinguishing this uncommon type from other round cell neoplasms. The accurate diagnosis can help expedite treatment of this highly aggressive tumor.