Laryngeal Squamous Cell Carcinoma with Osteosarcomatous Differentiation and Involvement of Thyroid Cartilage Mimicking Sarcoma Arising from Thyroid Cartilage.

Basaloid squamous cell carcinoma (BSCC) with a spindle cell component of the head and neck is an uncommon entity. In this case, we present a radiology-pathology correlation of a rare laryngeal BSCC with sarcomatous transformation and osteosarcomatous differentiation involving the laryngeal cartilage, which thus mimicked clinically and radiographically osteosarcoma or chondrosarcoma with calcification. Microscopic examination revealed predominantly BSCC with extensive osseous metaplasia among sheets and nests of basaloid tumor cells. There were also small foci of osteosarcoma, undifferentiated pleomorphic sarcoma, and spindle cell carcinoma. The presence of squamous cell carcinoma (SCC) in-situ, small areas of conventional SCC and diffuse positivity of p40 in conventional and basaloid squamous components confirmed that this tumor was indeed derived from surface squamous epithelium. Awareness of the broad differentiation potentials of SCC can avoid misdiagnosis of SCCs as sarcoma. This case emphasizes the importance of radiologic-pathologic correlation in definitive diagnosis and clinical management of laryngeal malignancies.