A 28-year-old man presents with a well-circumscribed, slow-growing endobronchial mass. Biopsy shows uniform cells with salt-and-pepper chromatin arranged in organoid nests. Mitotic count is less than 2 per 10 HPF and there is no necrosis. According to the WHO classification, this is best classified as:
- A Atypical carcinoid tumor
- B Typical carcinoid tumor ✓
- C Small cell carcinoma
- D Large cell neuroendocrine carcinoma
Correct answer: B. Typical carcinoid tumor
Explanation
Typical carcinoid is defined by less than 2 mitoses per 10 HPF and absence of necrosis. Atypical carcinoid shows 2-10 mitoses per 10 HPF and/or foci of necrosis. Small cell and large cell neuroendocrine carcinomas have high mitotic counts (typically >10 per 10 HPF) and extensive necrosis. The organoid pattern with salt-and-pepper chromatin is characteristic of well-differentiated neuroendocrine tumors.
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.