Hypercalcemia and Bone Metastasis in a Case of Large Cell Neuroendocrine Carcinoma With Unknown Primary

Figure 5

Morphologic features and immunoprofile are consistent with LCNEC. The origin of tumor could not be determined by IHC analysis. Neuroendocrine carcinomas may be TTF-1 positive, regardless of origin. Few cells weakly positive for CDX-2 suggest an appendix, pancreas, or intestinal primary. Immunohistochemistry showed positive CK7, AE1/AE3, synaptophysin, chromogranin, CD56, TTF-1 and p63 (scattered cells, weak), CDX-2 (few cells, weak), and Ki-67 proliferation index (99%).