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 54 year-old man presented with multiple, 1 month-old, itchy erythematous maculopapular patches on both legs, both arms, and back, which were diagnosed as prurigo nodularis. He had no underlying disease. Treatment with oral cyclosporine (50 mg/day) was started. However, his blood pressure exceeded the hypertension borderline after 8 weeks of treatment even though he had no underlying hypertension. Therefore, the treatment was changed to oral alitretinoin (30 mg/day) for 2 weeks. His itching sensation was reduced after the treatment without recurrence.