A 7-year-old boy has headaches, bitemporal visual field defects, and growth deceleration. Imaging shows a suprasellar cystic mass with prominent calcification. Surgical specimens show cords of squamoid epithelium with peripheral palisading, wet keratin, and stellate reticulum. Nuclear accumulation of beta-catenin would be expected because this tumor harbors activating mutations in:
- A BRAF
- B CTNNB1 ✓
- C GNAS
- D TP53
Correct answer: B. CTNNB1
Explanation
Adamantinomatous craniopharyngioma, the type seen in children with calcified cystic suprasellar masses, is driven by activating CTNNB1 mutations in the WNT pathway, producing nuclear and cytoplasmic beta-catenin accumulation in whorl-like clusters. BRAF V600E mutations define papillary craniopharyngioma, which occurs in adults and lacks calcification and wet keratin. GNAS characterizes fibrous dysplasia and pituitary adenomas in McCune-Albright syndrome.
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.