[Pruritic papulonodular lesions]

[Reactive perforating collagenosis]

BACKGROUND

Reactive perforating collagenosis (RPC) belongs to the group of perforating dermatoses, which comprises elastosis perforans serpiginosa, RPC, perforating folliculitis and Kyrle's disease. RPC was initially described as a distinctive form of transepithelial elimination of altered collagen related to superficial trauma. Two types are distinguished: a hereditary type (MIM 216700), which is rare and begins during early childhood, and a second type, called acquired RPC, which is more frequent, appears in adults and is associated with other diseases, diabetes mellitus, renal insufficiency, solid tumors, lymphomas and AIDS. We report the case of a young man whose illness began during infancy, militating in favor of a diagnosis of a hereditary form of RPC. The description of similar lesions in the patient's brother confirmed our diagnosis.

PATIENTS AND METHODS

A 26-year-old man, the child of consanguinous parents, presented crusted papular lesions on his hands. The cutaneous lesions, located on the external side of the limbs, had been present since childhood, with flares during winter. Histologic analysis showed a cup-shaped depression in the epidermis containing keratinous material with extruded degenerated collagen towards the cutaneous surface. Treatment with topic retinoids did not result in any real resolution of the disease. The patient reported the presence of similar lesions in his brother, which was consistent with our diagnosis.

DISCUSSION

The pathogenesis of hereditary RPC is still unknown, even if superficial trauma is suspected as the cause of RPC. In contrast, in diabetes, acquired RPC pathogenesis has recently been related to advanced glycation end-products of collagen.