Abstract

Hypo- and hyperpigmented mycosis fungoides (MF) are uncommon variants that occur in darker-skinned individuals. Hypopigmented MF frequently presents with hypopigmented patches in younger individuals with a CD8-predominant immunophenotype, while hyperpigmented MF typically presents in middle-aged to older individuals with grayish to hyperpigmented patches with a CD4-positive or CD4/CD8 double-negative infiltrate. We report a case of a young woman with hypopigmented MF and subsequent development of hyperpigmented MF. A 23-year-old woman, Fitzpatrick type IV, presented with hypopigmented patches on the trunk and extremities without surface change clinically suspicious for vitiligo. Skin biopsy demonstrated an infiltrate of atypical CD8-positive lymphocytes along the dermal-epidermal junction with epidermotropism; T-cell gene rearrangement studies (TCR) revealed a monoclonal T-cell population. She was diagnosed with hypopigmented MF and treated with phototherapy with resolution of hypopigmented areas. During the course of phototherapy, she noted progressive ovoid to linear gray hyperpigmented patches on the abdomen, back, inguinal folds, and proximal thighs with no systemic symptoms. Phototherapy was discontinued and she was treated with topical steroids and oral hydroxychloroquine for presumed erythema dyschromicum perstans, without improvement. Biopsy of a representative area revealed atypical CD3/CD4-positive, CD7-negative T-lymphocytes along the dermal-epidermal junction. TCR revealed a clonal T-cell population. Conclusion: Hypo- and hyperpigmented MF are uncommon variants of MF that more commonly occur in darker skinned individuals; despite different immunophenotypes, these variants may rarely occur in the same individual. Clinical suspicion and histopathologic correlation are required to differentiate hypo- and hyperpigmented MF from more common dermatoses such as vitiligo and erythema dyschromicum perstans.

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