Neuroendocrine tumors represent a heterogeneous category of neoplasm, with conflicting diagnostic and therapeutic demands. We here describe the case of a 72-yr-old woman with evidence of a poorly differentiated small-cell neuroendocrine carcinoma (NEC) localized in different endocrine glands and other non-endocrine organs. In particular, a large ovarian mass, multinodular thyroid goiter, right adrenal mass, cystic liver metastases and anterior mediastinum lymph node metastasis were present. The largest thyroid nodule caused tracheal restriction and dyspnea. Diagnosis of poorly differentiated metastasized NEC of unknown origin was made on the basis of histological and immunohistochemical findings, and treatment with etoposide (100 mg/m2 in days 1, 2 and 3) and cisplatinum (45 mg/m2 in days 2 and 3) was initiated. Simultaneously, im administration of octreotide LAR 20 mg every 28 days was started, according to the presence of SS receptors at 111In-octreotide scan. Rapid improvement of dyspnea and a reduction of the largest thyroid nodule, liver metastases and adrenal mass by 50% were observed after 3 months of treatment; the dimensions remained stable thereafter, while the pericardial lymph node disappeared. In conclusion, poorly differentiated NEC of unknown primary site is a well-recognized category, usually with an aggressive behavior, rapid growth rate and wide dissemination. Median survival of these patients is 6 months if left untreated. Our patient is alive 18 months after beginning the treatment, reporting good general condition and quality of life over the whole follow-up period.