Clinicopathological characteristics of xeroderma pigmentosum associated with keratoacanthoma in an infant.

A rare case of xeroderma pigmentosum coexisted with keratoacanthoma in an 18-month-old boy was reported. The boy was admitted with unequal size, irregularly shaped brown spots, patches and depigmentation spots on his face. A well-circumscribed hemispherical mass measuring 3 cm×3 cm with smooth surface and brown patches was observed beneath his left lower eyelid. Light microscopic examination of the skin lesions revealed epidermal hyperkeratosis, chronic inflammatory infiltration of the superficial dermal layer, and increases in melanocytes and melanin in the basal layer. The mass beneath the left lower eyelid was cup-shaped, consisting of proliferating squamous cells with a central keratin plug. The squamous epithelium was acanthotic with hypergranulosis. The adjacent epidermis formed exophytic projections resulting in a silhouette likened to lips. The patient was treated with a combination of antioxidant drugs, keeping the child from light and surgical excision of the mass. No recurrence has been observed.