Primary pulmonary hyalinizing clear cell carcinoma of bronchial submucosal gland origin.

Hyalinizing clear cell carcinoma (HCCC) has only been described in salivary glands of the head and neck. We report a 38-year-old man with a 2.6-cm lung tumor that was growing in a peribronchial location and had morphologic features of HCCC. The tumor cells expressed cytokeratin 7 and keratin AE1/AE3, and the vast majority of tumor cells marked also with p63 and p40. They were negative for cytokeratin 20, S-100, smooth muscle actin, napsin A, and thyroid transcription factor-1. Fluorescence in situ hybridization revealed Ewing Sarcoma Breakpoint Region 1 (EWSR1) rearrangement, and reverse-transcription polymerase chain reaction confirmed the presence of the EWSR1-Activating Transcription Factor 1 (ATF1) fusion transcript, which was subsequently sequenced. The morphologic, immunophenotypic, cytogenetic, and molecular findings together with the patient's history and location of the tumor support a diagnosis of primary pulmonary HCCC of bronchial submucosal gland origin. It is our understanding that this is the first report of HCCC arising as a primary tumor outside the head and neck region.