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.
A 75 year-old man presented with multiple scattered nodules and excoriated patches with crusts on the trunk, both arms, and both legs that were two weeks old. He had no underlying disease. The initial clinical diagnosis was prurigo nodularis and treatment was started. Despite treatment with oral cyclosporine (100 mg/day) for 3 years, his symptoms and skin lesions waxed and waned. After that, the treatment was changed to oral alitretinoin in a dose of 30 mg/day. Within 12 weeks of treatment, pruritus had improved and treatment with oral alitretinoin was stopped with partial remission.