A rare giant large cell neuroendocrine carcinoma: an ITMIG Tumor Board case report from a Turkish multidisciplinary team.

BACKGROUND: Large cell neuroendocrine carcinomas (LCNECs) of the thymus are rare, high-grade neuroendocrine neoplasms characterized by a high mitotic index and classified separately from thymomas, with markedly more aggressive behavior in terms of treatment response and prognosis. This study describes the treatment management of a patient who underwent surgery and received multimodal therapy for LCNEC. CASE DESCRIPTION: A contrast-enhanced thoracic computed tomography (CT) scan of a 52-year-old male patient revealed an anterior mediastinal mass measuring approximately 14 cm × 16 cm, with areas of calcification and cystic components. Following transthoracic fine-needle aspiration biopsy, which was consistent with LCNEC, the patient received three cycles of neoadjuvant chemotherapy and subsequently underwent thymectomy via median sternotomy. Histopathological examination confirmed the diagnosis of LCNEC, after which adjuvant therapy was administered. The patient has remained disease-free during follow-up for 40 months. CONCLUSIONS: LCNEC is an exceptionally rare subtype, accounting for only a very small proportion of all thymic epithelial tumors. Given the aggressive course of LCNEC and its potential for both local invasion and distant metastasis, a multimodal treatment approach is required. This treatment sequence represents a rational strategy consistent with previous studies advocating combined-modality management for advanced or recurrent thymic malignancies.