Dermoscopy of skin lesions in two patients with xeroderma pigmentosum

Summary Background Xeroderma pigmentosum (XP) is a rare disorder produced by a genetic defect in the repair of DNA damage caused by ultraviolet radiation. The early diagnosis of malignant skin tumours is crucial in the survival of patients with XP, but this is not easy even for experienced dermatologists due to the presence of a high number of actinic lesions. Dermoscopy is a new diagnostic method that increases the diagnostic accuracy for skin tumours. Objectives To describe the clinical and dermoscopic features of different benign and malignant lesions [focusing on malignant melanoma, basal cell carcinoma (BCC) and benign melanocytic naevi] in two patients with XP. Methods Three dermatologists with experience in pigmented skin lesions and dermoscopy examined two siblings with XP over a period of 54 months. Diagnosis of skin tumours was obtained using clinical examination and dermoscopy with 10‐fold magnification and digital images. All the tumours with criteria of malignancy were excised for further histopathological analyses. Results Multiple skin tumours showing some degree of pigmentation were detected in the patients. Clinical and dermoscopic examination allowed the discrimination of four melanomas (three of them in situ), 26 BCCs and five dysplastic naevi from other pigmented skin lesions. The features and parameters previously described for dermoscopy were shown to be appropriate for the recognition of tumours in our patients with XP. Generalized actinic lentigos were distinguished from BCCs by the presence of a delicate brown pigmented network. Fine vessels from poikiloderma were differentiated from the arborizing telangiectasia of BCC. Conclusions The dermoscopic findings in the tumours were similar to those previously described in patients not affected by XP. Diagnosis by dermoscopic pattern analyses allowed a correct classification of malignant tumours in these cases.