Large cell neuroendocrine carcinoma of the lung with calcification and expression of osteopontin.

A large cell neuroendocrine carcinoma (LCNEC) is a rare neoplasm. In this article, we report a case of LCNEC with stromal calcification. A 46-year-old Japanese man was found to have an abnormal shadow in the left upper lobe in a chest X-ray. As the size of the tumor increased during the follow-up, a left upper lobectomy was performed. Histological examination disclosed neuroendocrine morphology consisting of large cells, and subsequent immunohistochemistry confirmed the neuroendocrine differentiation. A diagnosis of LCNEC was established. Additionally, calcification was observed in the stroma within the tumor. Immunohistochemically, parts of neoplastic cells of LCNEC and calcified foci were positive for osteopontin. Finally, we suggest that osteopontin as well as dystrophy within the tumor may be involved in the stromal calcification of LCNEC.