Abstract
: Most primary small cells carcinoma develop from the lung, and extra-pulmonary small cell carcinoma accounts for less than 5% of all small cell carcinoma cases. In the head and neck region, the most common sites are the larynx and salivary glands; however primary involvement of the palate is extremely rare. The extra-pulmonary small cell carcinoma is similar to its pulmonary counterpart regarding morphology, immunohistochemistry, and electron microscopy features and derives from pluripotential stem cells that develop neuroendocrine features. There is growing evidence regarding the ability of extra-pulmonary small cell carcinoma to arise from pluripotent basilar cells capable of divergent differentiation with the consequence of arising neuroendocrine phenotype as a trans-differentiation phenomenon in the progression of an organ-specific carcinoma. The differentiation between primary and metastatic extra-pulmonary small cell carcinoma is challenging. There is also no standard guideline for treatment as it is a rare occasion, and there is no consensus between radiation oncologists and cancer surgeons about the best treatment strategy. In this study, a very rare case of hard palate small cell carcinoma with neuroendocrine pathology features is presented. To our best of knowledge, this is the third case report of extra-pulmonary small cell carcinoma involving the palate in the literature review. Knowing the clinical presentation and pathology characteristics of such rare tumor in addition to follow-up outcome can be highly useful to establish a reliable guideline for hard palate small cell carcinoma management.