Hypopigmented Mycosis Fungoides: A Clinical Mimicker of Vitiligo

February 2015 | Volume 14 | Issue 2 | Case Report | 193 | Copyright © 2015

Stanislav N. Tolkachjov MD and Nneka I. Comfere MD

Department of Dermatology and Laboratory Medicine and Pathology. Mayo Clinic. Rochester, MN

Abstract

Hypopigmented mycosis fungoides (HMF) is a rare variant of cutaneous T-cell lymphoma (CTCL) that often manifests in younger patients with darker skin types in a centripetal distribution.1 Average age of diagnosis is often 14 years.2 The diagnosis is often missed due to its low incidence and lack of clinical suspicion. Misdiagnosis and failure to obtain biopsies lead to a long latency period from onset of hypopigmented patches to diagnosis and treatment.
HMF has a clinically benign course and responds well to therapy; however, relapse is common.3 We report a case of HMF misdiagnosed as vitiligo in order to illuminate diagnostic, histopathological, and treatment modalities.

J Drugs Dermatol. 2015;14(2):193-194.

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CASE REPORT

A 21-year-old woman of Fitzpatrick skin type V presents with a 6-month history of progressive, pruritic hypopigmented macules, without redness or scale, involving the upper and lower extremities. She describes sparing of the face and torso. She denies a preceding upper respiratory or gastrointestinal infection. She does not report associated constitutional symptoms including fevers, chills, or night sweats. She has no prior personal or family history of dermatitis, psoriasis, vitiligo, or autoimmunity. Prior diagnosis made by 4 local physicians included vitiligo.

On examination, she has Fitzpatrick skin type V. On the upper and lower extremities bilaterally, including the dorsal hands and feet, she has variably sized, 6mm to 1cm in diameter, hypopigmented macules with subtle pink erythema. Sparing of the face and torso is noted. No overlying scale present. Lesional and uninvolved skin biopsies were done from corresponding sites on her bilateral arms.

Lesional skin biopsy of a hypopigmented macule demonstrated an atypical superficial dermal band-like CD8 predominant T-cell infiltrate with prominent epidermotropism. The atypical lymphoid cells have irregular nuclear contours, hyperchromatic and enlarged nuclei. The atypical epidermotropic T-cells are immunoreactive for CD2, CD3, CD7 (partial), CD8, T-cell receptor beta F1 and non-immunoreactive for CD30 and T-cell receptor gamma delta. Diminished CD7 staining is noted within this atypical lymphoid infiltrate. Scattered reactive CD4-positive T-cells are present within the epidermis and superficial dermis. Molecular studies for T-cell receptor gene rearrangement are equivocal due to minimal amounts of DNA (limited template). The constellation of the morphologic, immunophenotypic and molecular genetic findings are compatible with mycosis fungoides. Peripheral blood flow cytometry, performed as part of her staging, is negative. Narrowband UVB and topical triamcinolone were recommended.

DISCUSSION

Hypopigmented Mycosis Fungoides (HMF) is a rare variant of cutaneous T-cell lymphoma (CTCL) that clinically presents as hypopigmented macules and patches typically on the extremities. As evident in this patient’s history, it is often mistaken for vitiligo, tinea versicolor, or pityriasis alba.3 HMF largely affects darker complected, young individuals in their early 20’s; however, the age range in 2 large studies is quite broad from 4 to 45 years old.2, 4 The indolent behavior of HMF and its frequent misdiagnosis contributes to a latency period between appearance of lesions and diagnosis averaging 9.2 years. The definitive diagnosis often depends on histopathologic interpretation after clinical suspicion; therefore, a lesional biopsy is crucial.

Histopathologic features include epidermotropism of single or clustered, atypical, lymphocytes with hyperchromatic nuclei and irregular contours.5 CD8+ T cells are more prominent proportionally; 6 however, this is not always the case. This finding is in contrast to the CD4+ T-cell predominance observed in classic MF. Clonal T-cell receptor gene rearrangement is frequently

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