An 8-year-old girl with numerous hypopigmented, ulcerated, and crusted patches on her face and forearms develops an indurated, crater-like, skin nodule on the back of her left hand. Biopsy of this skin nodule discloses a squamous cell carcinoma. Molecular biology studies reveal that this patient has germline mutations in the gene encoding a nucleotide excision repair enzyme. What is the appropriate diagnosis?

Options Xeroderma pigmentosum is an autosomal recessive disease Increased sensitivity to sunlight is accompanied by a high incidence of skin cancers, including basal cell carcinoma, squamous cell carcinoma, and malignant melanoma. Several xeroderma pigmentosum genes are involved in nucleotide excision of ultraviolet-damaged DNA. Li-Fraumeni syndrome (choice C) refers to an inherited predisposition to develop cancers in many organs due to germline mutations of p53. Ataxia-telangiectasia (choice A) features cerebellar degeneration, immunologic abnormalities, and a predisposition to cancer. Patients with hereditary albinism (choice B) are also at high risk for the development of squamous cell carcinoma of the skin, but they do not have a defect in DNA excision repair. Diagnosis: Xeroderma pigmentosum