A 75-year-old farmer presents with a pearly, telangiectatic nodule with a rolled border on the nose. Biopsy shows tumor islands of basaloid cells with peripheral palisading and retraction artifact between tumor and stroma. This tumor is associated with mutations in which tumor suppressor gene, also mutated in basal cell nevus syndrome?

• A PTCH1 (Patched 1) ✓
• B TP53
• C RB1
• D CDKN2A

Explanation

Basal cell carcinoma (BCC) is the most common human malignancy and is strongly linked to UV-induced mutations in PTCH1, the Hedgehog pathway receptor. PTCH1 normally inhibits Smoothened (SMO); loss of PTCH1 leads to constitutive Hedgehog signaling and uncontrolled proliferation. Gorlin syndrome (basal cell nevus syndrome) is an autosomal dominant condition caused by germline PTCH1 mutations, leading to multiple BCCs, odontogenic keratocysts, calcified falx cerebri, and skeletal anomalies.

Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.