Weenig, Roger H.

Background: Folliculotropic mycosis fungoides (FMF) is a variant of cutaneous T-cell lymphoma that has clinical overlap with a variety of inflammatory follicular unit disorders. However, we describe distinctive presentations of FMF with acneiform features that can be diagnostically challenging, leading to diagnostic delay. Objective: To highlight the importance of histopathologic and immunohistochemical evaluation for diagnostic confirmation of presumed inflammatory follicular unit–based disorders that are unusual in presentation or unresponsive to standard therapies. Methods: A cross-sectional retrospective study of 5 consecutive patients with a histopathologic diagnosis of FMF was conducted. The clinical, histopathologic, immunophenotypic, and molecular genetic features of cases are presented. Results: We describe 5 patients with clinical and histopathologic presentations of FMF masquerading as hidradenitis suppurativa, furunculosis, or acne vulgaris (age range 34–66 years, 4:1 female to male). Clinical morphologies included open and closed comedones, inflammatory pustules, papules and nodules, follicular papules with keratotic plugging, cysts, and scarring involving the face, trunk, and intertriginous areas. All patients failed to respond to standard therapies, including topical and oral antibiotics, topical and oral retinoids, or topical corticosteroids, before receiving the diagnosis of FMF. Lesional skin biopsies showed a perifollicular CD4-positive T-lymphocytic infiltrate with pilotropism, intrafollicular mucin deposition, foreign-body granulomatous inflammation, acute inflammation, and follicular epithelial necrosis. None had concurrent systemic mycosis fungoides. Limitations: Small retrospective cohort study. Conclusion: We present these cases to expand the clinical and histopathologic spectrum of FMF that may strikingly resemble acneiform disorders and to highlight the importance of diagnostic reconsideration with histopathologic evaluation.

Cutaneous gamma‐delta T‐cell lymphoma (γδTCL) is a rare malignancy that typically displays an aggressive clinical course. We present an unusual case of a 57‐year‐old woman with a 3‐year history of lower extremity nodules. Histopathologic, immunophenotypic and molecular genetic studies revealed a clonal, predominantly pannicular gamma‐delta T‐cell infiltrate, leading to a diagnosis of cutaneous γδTCL. The clinical course was characterized by rapid improvement within months of starting systemic corticosteroids, with relapse in ulcerations but no new lesions more than 3 years after onset of disease. Our case and seven previously reported patients with indolent and relatively localized cutaneous γδTCL provide evidence that not all cases of this entity carry a poor prognosis. This indolent subset adds complexity to treatment of cutaneous γδTCL.