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.

Desmosomes and microvilli mean a lot: diagnosis of neoplasms of unknown origin using electron microscopy.

Neoplasms of unknown origin present a difficult diagnostic dilemma, particularly if they are very poorly differentiated. Adenocarcinomas, squamous cell carcinomas, melanomas, lymphomas, and sarcomas can all be very difficult to diagnose if the light microscopic cytomorphology is sufficiently undifferentiated. Electron microscopy (EM) can either demonstrate differentiation or narrow the range of differential diagnoses. The authors report the case of a 64-year-old male who has been HIV positive for several years and was found to have expansile lytic lesions in several ribs and a thumb fracture associated with a soft tissue mass which was biopsied. The tumor was composed of very pleomorphic malignant cells without specific differentiation. The malignant cells stained positive for pancytokeratin (AE 1/3), EMA, CEA, CK20, and CK7. Rare cells had mucicarmine-positive intracytoplasmic droplets. They were negative for S-100, calretinin, CD45, MART-1, and vimentin. EM revealed intracytoplasmic lumina with long microvilli and many well-formed desmosomal junctions. The diagnosis was initially very broad. Immunohistochemistry narrowed the diagnosis to carcinoma, but EM alone was able to narrow the diagnosis to poorly differentiated adenocarcinoma. In a neoplasm of unknown origin, EM can either narrow the differential significantly or, in the case of limited material, provide information that otherwise may not be attainable.

Fine-needle aspiration cytology of metastatic carcinoid tumor: report of a case and review of the literature.

While carcinoid tumor is a relatively common neoplasm in surgical pathology, fine-needle aspiration (FNA) cytology as a method of primary diagnosis has only been reported in the literature a few times. We report on the case of a 42-yr-old female with multiple large metastatic tumor deposits in her liver, pelvic adnexae, bones, and lungs, with an unknown primary. FNA was performed on one of the liver masses, and was diagnosed using routine histochemical and immunohistochemical stains as carcinoid tumor. No follow-up tissue diagnosis has been obtained. However, the patient is still alive with her tumor 1 yr later. Fine-needle aspiration cytology can be a useful and safe tool in the diagnosis of metastatic carcinoid tumors, avoiding the need for surgery which would not otherwise be indicated for treatment.