A 38-year-old man from Delhi presents with episodic headaches, profuse sweating, and palpitations for 6 months. Plasma free metanephrines are elevated. Imaging reveals a 3 cm left adrenal mass. Which is the most common hereditary syndrome associated with pheochromocytoma in this patient's demographic?

Explanation

## Hereditary Syndromes Associated with Pheochromocytoma **Key Point:** Neurofibromatosis type 1 (NF1) is the most common hereditary syndrome predisposing to pheochromocytoma in the general population, with a prevalence of 1–5% in NF1 patients. ### Comparative Epidemiology of Hereditary Pheochromocytomas | Syndrome | Gene | Frequency in PCC | Bilateral Adrenal | Malignancy Risk | Age of Onset | |----------|------|------------------|-------------------|-----------------|---------------| | NF1 | NF1 | 1–5% of NF1 patients | 5% | 12% | 40–50 years | | MEN 2A/2B | RET | 50% of MEN 2 patients | 60% | <5% | 30–40 years | | VHL | VHL | 10–20% of VHL patients | 80% | 5% | 20–30 years | | Familial paraganglioma | SDHA, SDHB, SDHD, SDHAF2 | Rare in general population | Rare | 30–40% | Variable | **High-Yield:** Among hereditary syndromes, **MEN 2A/2B** has the highest penetrance (50% of carriers develop pheochromocytoma), but **NF1** is the most common hereditary cause overall because NF1 itself is more prevalent (1 in 3,000 births) than MEN 2 (1 in 30,000). ### Clinical Features Suggesting Hereditary Disease 1. **Age <40 years at diagnosis** — suggests hereditary etiology 2. **Bilateral adrenal involvement** — highly suggestive of MEN 2A, VHL, or NF1 3. **Extra-adrenal paragangliomas** — suggests SDH mutations 4. **Family history** — essential screening clue 5. **Associated features:** - NF1: café-au-lait spots, neurofibromas, optic nerve gliomas - MEN 2A: medullary thyroid carcinoma (MTC), primary hyperparathyroidism - VHL: hemangioblastomas, renal cysts, pancreatic cysts **Mnemonic:** **"NF1 is the Most Common Hereditary PCC Cause"** — Remember: NF1 prevalence is highest, so even though MEN 2 has higher penetrance, NF1 produces more absolute cases. **Clinical Pearl:** All patients with newly diagnosed pheochromocytoma should be screened for NF1 (clinical examination for neurofibromas, café-au-lait spots) and should have genetic counselling. Genetic testing for *RET* (MEN 2), *VHL*, *NF1*, and *SDH* genes is recommended, especially if <40 years old, bilateral disease, or family history.