Acquired reactive perforating collagenosis following diclofenac therapy in a patient with parapsoriasis

A case of acquired reactive perforating collagenosis in a 70-year old man with a long standing digitate parapsoriasis is reported. Multiple asymptomatic cutaneous hyperpigmented papules with a central adherent keratotic plug developed simultaneously with widespread purpuric eruption following a single i.m. diclofenac injection. Histologic examination of a keratotic lesion revealed an epidermal crater with centrally degenerated collagen and elastic fibre extrusion. This case is interesting for the lack of pruritus, the transepithelial elimination of both collagen and elastic fibres and the association with parapsoriasis. The etiologic role of diclofenac is discussed. The term acquired perforating dermatosis may be more suitable for this case.