BACKGROUND: An atypical presentation of large-cell neuroendocrine carcinoma was diagnosed from a metastatic nodule on the chest wall.

CASE REPORT: The patient was a 60-year-old female who presented with intractable back pain with an MRI showing an L3 compression fracture and multiple lesions in L3, L5, and the pelvis. The patient had a 40-pack/year smoking history. On admission, a small, non-tender nodule was noted under her left breast on the chest wall. CT and PET scan confirmed diffuse metastases in the lumbar spine, brain, lung, liver, and pancreas, without knowing the primary site. The patient underwent L3 vertebroplasty and removal of the nodule on the chest wall. The pathology report of the nodule showed large cell neuroendocrine carcinoma (LCNEC). Immunohistochemical stains were positive for cytokeratin AE 1/3, TTF-1, CD56, Synaptophysin, and chromogranin. The stains were negative for CK7, Napsin, cytokeratin 20, GATA-3, mammaglobin, and CEA. A pathology diagnosis of  metastatic LCNEC was made, with the lung as the most likely original site.

CONCLUSIONS: Treatment consisted of pain control through an intra-thecal pump and whole brain radiation followed by systemic chemotherapy. This case elucidates the unusual cutaneous metastatic site for LCNECs, which was biopsied to confirm the diagnosis. This is the first case of LCNEC diagnosed by a cutaneous metastasis. In conclusion, it is possible to diagnose LCNEC of the lung at a distant metastatic site with careful histological and immunohistochemical examination, which can spare patients from more harmful biopsies.

Keywords: Carcinoma, Neuroendocrine