Multiple Basal Cell Carcinomas in a Long-Term Survivor of Childhood ALL and HSCT—A Call for Dermatologic Vigilance

(1) Background: Cutaneous secondary malignant neoplasms are a growing survivorship burden after pediatric cancers and hematopoietic stem cell transplantation (HSCT), yet skin-focused surveillance remains inconsistently implemented. (2) Objective: To synthesize current molecular dermatology insights relevant to prevention, early detection, and treatment of basal cell carcinoma (BCC) in high-risk survivors, while anchoring the discussion in a detailed case of multiple BCCs after childhood acute lymphoblastic leukemia and HSCT. (3) Methods: Narrative review integrating clinical, dermoscopic, molecular, and translational data from recent high-impact studies; case retained in full. (4) Results: Radiation exposure (especially total body irradiation), prior immunosuppression, and persistent immune dysregulation synergize with ultraviolet mutagenesis to create a "field cancerization" state characterized by Hedgehog-pathway activation (Patched1/Smoothened), impaired Deoxyribonucleic Acid damage response, and stromal remodeling. Dermoscopy, when embedded in routine whole-body examinations, markedly improves accuracy for keratinocyte cancers. Chemoprevention (e.g., nicotinamide) and targeted therapies (hedgehog inhibitors; Programmed Death-1 blockade) represent key translational levers for care innovation. (5) Conclusions: Integrating structured dermatologic surveillance with molecularly informed prevention and therapy should be standard in survivorship pathways for hematopoietic stem cell transplantation/Radiotherapy-exposed patients.