Background: Folliculotropic mycosis fungoides represents a rare variant of the CD4-positive cutaneous T-cell lymphoma mycosis fungoides. It is characterized by tropism of the lymphocytic infiltrate for hair follicle and other adnexal structures.
Case presentation: Our patient presented with a 20-year history of pruritic skin lesions, which had been diagnosed as atopic dermatitis. The diagnosis of folliculotropic mycosis fungoides was confirmed by skin biopsy. Since topical therapy was ineffective, systemic therapy was initiated promptly. Treatment with pegylated interferon alpha-2b 25 µg/week led to significant improvement of the skin condition.
Conclusion: Due to its polymorphic clinical presentation, folliculotropic mycosis fungoides is diagnosed with delay and in a later stage than classical mycosis fungoides. Thus we recommend an early skin biopsy in patients with therapy-resistant pruritic skin lesions.