A 24-year-old woman with Cushing syndrome has multiple 1 to 3 mm darkly pigmented micronodules scattered through both adrenal cortices, with internodular cortical atrophy. Imaging shows no mass lesion. Echocardiography reveals a cardiac myxoma and skin examination shows lentigines and blue nevi. Germline testing would most likely show a mutation in:
- A RET
- B MEN1
- C PRKAR1A ✓
- D TP53
Correct answer: C. PRKAR1A
Explanation
Primary pigmented nodular adrenocortical disease (PPNAD) is the adrenal manifestation of Carney complex, an autosomal dominant disorder caused by germline PRKAR1C mutations encoding the regulatory subunit of protein kinase C. It produces ACTH independent Cushing syndrome with bilateral pigmented cortical micronodules and atrophy of the intervening cortex. Associated findings include cardiac myxomas, psammomatous melanotic schwannomas, and lentigines. MEN1 and RET cause other syndromes, and TP53 underlies Li-Fraumeni rather than Carney complex.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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