Metastatic laryngeal basaloid squamous cell carcinoma simulating primary small cell carcinoma of the lung on fine needle aspiration lung biopsy. A case report.

BACKGROUND: First described in 1986, the basaloid squamous variant of laryngeal carcinoma is an uncommon, aggressive neoplasm with early presentation of metastatic disease and widespread dissemination. It is characterized primarily by its biphasic morphologic appearance.

CASE: A 64-year-old female smoker presented with left hilar and right lower lung lobe masses. The fine needle aspiration cytologic findings were consistent with features of primary undifferentiated small cell carcinoma.

CONCLUSION: The basaloid squamous cell carcinoma of head and neck region is a highly malignant neoplasm with frequent metastatic disease at the time of diagnosis. Metastatic deposits may consist of basaloid and/or squamous carcinoma cells. The basaloid component of this biphasic neoplasm is poorly differentiated and demonstrates cytologic features that mimic undifferentiated small cell carcinoma. Previous reports of cervical lymph node metastases from basaloid squamous carcinoma indicate frequent misdiagnosis as small cell carcinoma. Pulmonary metastases are more problematic since they introduce the possibility of a second primary lesion in these patients who have a frequent history of cigarette and/or ethanol abuse. Immunohistochemistry is useful in the distinction of metastatic basaloid squamous carcinoma from a second primary cell carcinoma of the lung.