Zosteriform Mycosis Fungoides: A Case Report and Literature Review.

Abstract: Primary cutaneous lymphomas are the third most common lymphomas, with mycosis fungoides (MF) being the predominant subtype of cutaneous T-cell lymphoma. Zosteriform distribution of MF is a rare presentation, complicating diagnosis and management because of its resemblance to other skin disorders. This subtype usually presents with typical lesions of classic MF, including patches and patches that progress to plaques and sometimes tumors, but in a distribution limited to a dermatomal distribution. This case involves a 29-year-old woman with a recurrent, unilateral itchy, and painful rash on her lower back, misdiagnosed for a decade as fungal infection and eczema. The rash evolved into a resistant scaly plaque, unresponsive to steroids and phototherapy. Histopathologic examination of skin biopsies suggested large plaque parapsoriasis. Based on clinical, histologic, and therapeutic response features, a final diagnosis of early-stage MF was established. The patient showed partial improvement after treatment with methotrexate and corticosteroids. Zosteriform MF is a rare and challenging variant, showing relatively good prognosis in most cases. Literature review highlights its occurrence across a wide age range, with prior herpes zoster viral infection proposed as a potential trigger influencing disease onset and distribution. Treatment outcomes vary, with some patients benefiting from immunosuppressive therapies, while others experience recurrence or poor prognosis. Zosteriform MF is a rare, diagnostically challenging variant of MF. This case underscores the importance of thorough diagnostic evaluation and the potential for variable treatment responses. Further research is needed to understand its pathogenesis and optimize therapeutic strategies.