A 61 year-old man presented with several one month-old erythematous to brownish papules and nodules on the back and both legs (a,c). He had diabetes mellitus. The initial clinical suspicion was prurigo nodularis and punch biopsy was done. Microscopic examination showed hyperkeratotic epidermis with acanthosis and parakeratosis. Elongated and irregular rete ridges were observed with dense dermal perivascular infiltration (a,b). The final diagnosis was prurigo nodularis. Initially, he was treated with oral cyclosporine 100 mg/day for 4 weeks. However, relief of the symptoms was insufficient and oral alitretinoin was started at a dose of 30 mg/day. After 4 weeks of alitretinoin treatment, symptoms and skin lesions were improved, and with 8 weeks of treatment (b,d), he stopped medical treatment and achieved complete remission without recurrence.
A 41 year-old woman presented with multiple, 2 year-old, scattered erythematous to brownish papules with pruritus on both legs. She had diabetes mellitus. The initial clinical suspicion was reactive perforating collagenosis and punch biopsy was performed. Atrophic and ulcerative epidermis was observed. There was cup-shaped invagination of the epidermis associated with a keratin plug containing inflammatory debris and collagen fibers (d,e). Reactive perforating collagenosis and prurigo nodularis were finally diagnosed. After the use of oral cyclosporine (100 mg/day) for 4 weeks without improvement, oral alitretinoin (30 mg/day) was started. Within 5 weeks of alitretinoin treatment, her pruritus and skin lesions improved. After that, she stopped medical treatment without progression or recurrence.