Extensive Alopecia Mucinosa and Response to Brentuximab Vedotin: A Case Report.

Introduction: Follicular mucinosis (FM) is characterized by mucin deposition within hair follicles and sebaceous glands, sometimes causing irreversible alopecia. In adults, it is often secondary to cutaneous T-cell lymphoma (CTCL), particularly the folliculotropic mycosis fungoides (FMF) variant. Extensive scalp involvement is rare and may mimic inflammatory or infectious disorders, delaying diagnosis. Case Presentation: A 64-year-old woman presented with progressive diffuse alopecia, suppurative scalp nodules, comedones, leonine facies, and multiple erythematous plaques. Initial biopsies elsewhere suggested tuberculoid leprosy, and multidrug therapy produced no improvement. Trichoscopy showed nonspecific signs suggestive of dissecting cellulitis, but histopathology revealed mucinous follicular destruction and a perifollicular lymphocytic infiltrate with immunophenotypic features of CTCL. Large-cell transformation was present in 10% of the infiltrate. Staging confirmed advanced FMF with secondary FM. Treatment with brentuximab vedotin achieved partial hair regrowth and skin improvement. Conclusion: This case describes an unusual presentation of FMF, in which diffuse alopecia with suppurative nodules was the first manifestation of secondary FM. Brentuximab vedotin may have a therapeutic role in mucinous alopecia in this context.