Poorly differentiated Neuroendocrine carcinoma (small cell) of Parotid Gland and ‘Moderately differentiated’ Hepatic metastases: a Discordant Histopathology clarified by dual tracer PET-CT (⁶⁸Ga-DOTATATE and ¹⁸F-FDG) for predicting tumor biology and treatment decision-making

Abstract

Metastatic neuroendocrine neoplasms (NEN) of the parotid gland, with discordant histopathology reports between primary parotid tumor (poorly differentiated small cell neuroendocrine carcinoma) and large hepatic metastasis (atypical carcinoid with moderately differentiation status, Ki-67 15-20%), and the value of dual tracer PET-CT imaging (⁶⁸Ga-DOTATATE and ¹⁸F-FDG) features in such clinical setting are illustrated. Minimal ⁶⁸Ga-DOTATATE and high grade ¹⁸FDG uptake of the lesions indicated a poor differentiation status helped in clarifying tumor biology, with its potential implications for subsequent treatment-decision individualization in favor of chemotherapy. The findings underscore the clinical utility of dual tracer PET-CT in appropriating the assessment in patients/situations with conflicting or discordant histopathology at two sites in an individual.