Abstract:
Introduction: Xeroderma pigmentosum (XP) is a rare autosomal recessive DNA repair disorder characterized by extreme photosensitivity and a markedly increased risk of cutaneous malignancies. Pediatric presentations with multiple synchronous malignant transformations are exceptionally uncommon, typically associated with aggressive progression and poor prognosis, especially when diagnosis is delayed.
Objective: To describe the case of a pediatric patient with advanced XP and multiple synchronous cutaneous malignancies, highlighting the diagnostic and therapeutic challenges associated with delayed recognition and lack of follow-up.
Case Description: A 6-year-old male from the State of Mexico presented with skin lesions since 7 months of age following sun exposure, without medical follow-up. He was admitted in April 2026 for bilateral purulent conjunctival discharge of 3 months' duration, unresponsive to topical antibiotics. Examination revealed disseminated dermatosis in photoexposed areas with multiple pigmented, exophytic, keratotic, and ulcerated neoformations (largest ~10 cm, malar region); bilateral blindness due to cicatricial symblepharon, ectropion, and limbal stem cell deficiency; cervical lymphadenopathy with a surgically drained intraparotid abscess; global neurodevelopmental delay; and severe chronic malnutrition. PET-CT showed hypermetabolic cutaneous and nodal lesions. Biopsies confirmed invasive squamous cell carcinoma at multiple sites (nasal ala, labial commissure, ocular canthus, bilateral conjunctiva), basosquamous carcinoma, and a collision tumor (basal cell carcinoma + primary cutaneous melanoma). Genetic subtyping is pending, though phenotype and frequency suggest XP type A or C. Treatment was initiated with pembrolizumab (anti-PD-1), 2 mg/kg with premedication.
Conclusion: Pediatric XP with multiple malignant transformation represents an exceptional diagnostic and therapeutic challenge. Delayed diagnosis results in advanced disease with an ominous prognosis, underscoring the need for timely clinical recognition, strict photoprotection from birth, and multidisciplinary follow-up to improve survival and quality of life.
Keywords: Xeroderma pigmentosum; collision tumor; basal cell carcinoma; pediatric oncology; DNA repair disorder
