A 62-year-old heavy smoker presents with a large central lung mass. Biopsy shows a neuroendocrine tumor with organoid nesting pattern, abundant cytoplasm, prominent nucleoli, high mitotic count (15 mitoses per 2 mm²), and necrosis. According to WHO classification, what is the diagnosis?
- A Large cell neuroendocrine carcinoma ✓
- B Atypical carcinoid tumor
- C Small cell carcinoma
- D Typical carcinoid tumor
Correct answer: A. Large cell neuroendocrine carcinoma
Explanation
Large cell neuroendocrine carcinoma (LCNEC) requires neuroendocrine morphology (organoid, palisading, or rosette-like patterns), high mitotic rate (>10 per 2 mm²), necrosis, and non-small cell cytologic features (abundant cytoplasm, prominent nucleoli). Typical carcinoid has <2 mitoses/2mm² without necrosis. Atypical carcinoid has 2-10 mitoses and/or focal necrosis. Small cell carcinoma has scant cytoplasm and fine chromatin.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.