Medicina Molecular e Genética

Combined Small Cell Carcinoma and Squamous Cell Carcinoma of the Parotid Gland: Immunohistochemical and Molecular Characterization

Abstract

Domenico Trombetta, Chiara Copelli, Paolo Graziano, Illuminato Carosi, Flavia Centra, Federico Pio Fabrizio, Maria Carmina Manzorra, Lucia Anna Muscarella and Roberto Cocchi

Combined SCC and SqCC of salivary gland are defined as a composite tumor and it represents an even more rare entity, often recognized just after evaluation of the surgical specimen. Here we report an extraordinary case of combined SCC and SqCC of the parotid gland in a 73-year-old man with a prior medical history of cutaneous squamous cell carcinoma. A computed tomography scan showed a 3 cm-sized heterogeneous mass in the parotid region while no other primary tumor or metastasis and lymphadenopathy were detected. The patient underwent to a partial parotidectomy and morphological and immunohistochemical features of the tumor were consisting in combined SCC and SqCC. SqCC component was immunoreactive for p40 whereas SCC neoplastic cells resulted strongly positive either for synaptophysin and chromogranin and negative either for p40 or high molecular weight cytokeratins. To identify the main putative genetic alterations specific for each histotype component, we performed a molecular profiling of FGFR1, MET, MYC, TP53, BRAF, NOTCH1, EGFR, NFE2L2, PDGFRa, cKIT, and PIK3CA genes. Interestingly, these analyses did not disclose any known genetic alterations in any neoplastic component of the combined tumor. To the best of our knowledge, this is the first detailed report of a combined small cell and squamous cell carcinoma of the parotid gland. Our case did not show any known molecular signature. Further investigation will clarify the pathogenesis and relationship of the individual components and will be of great utility for the treatment of these extremely rare entity..