Hypopigmented Patches on the Skin FREE

A 47-year-old man presents with a 1-year history of a mildly pruritic eruption on the trunk and extremities. He has no significant medical history and takes no medications. He denies any recent travel or close contact with persons or animals having a similar eruption. Review of systems is negative. On physical examination, he has hypopigmented round patches with fine cigarette-paper scaling centrally located on his proximal arms, hips, thighs, lateral chest wall, and flanks (Figure 1). Sensation is intact over the affected skin. Examination of skin scrapings using potassium hydroxide is negative for hyphae, and there is no palpable lymphadenopathy.

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Hypopigmented mycosis fungoides

D. Obtain a skin biopsy

The key clinical feature is the presence of round geometric hypopigmented patches with fine cigarette-paper scale distributed on sun-protected skin, which is classic for patch-stage mycosis fungoides. A skin biopsy can confirm the diagnosis (Figure 2).

The differential diagnosis for hypopigmented patches on the skin includes tinea corporis, tinea versicolor, progressive macular hypomelanosis, vitiligo, pityriasis alba, lichen sclerosus et atrophicus, morphea, sarcoidosis, leprosy, and syphilis. It is important first to rule out common causes of hypopigmentation with fine scaling, such as tinea corporis and tinea versicolor, using potassium hydroxide preparation. Evaluation of cutaneous sensation is necessary to rule out leprosy. Empirical topical steroids may improve skin lesions and pruritus but will alter the histologic pattern on future skin biopsies and further delay a correct diagnosis. Often, several skin biopsies are needed to confirm the diagnosis of mycosis fungoides. Diagnostic imaging is not indicated in patients without tumors, lymphadenopathy, or other evidence of systemic involvement.

Hypopigmented mycosis fungoides is a rare clinical variant of mycosis fungoides. The average age of onset is approximately 20 years,¹ with a range of 2 to 77 years in published reports.^2- 4 In contrast, the average age of onset is 51 years for classic mycosis fungoides.²

More than 80% of affected patients have darker skin types.^1,5 Patients present with hypopigmented patches on the trunk and extremities, with or without associated erythema and scaling. Hyperpigmented patches may also be represented.¹ Lesions are generally asymptomatic. The disease has an indolent course, with rare case reports of progression to tumor or systemic involvement.¹ Prognosis is good, with a 20-year overall and disease-specific survival of 98%.⁶

Histopathology of hypopigmented mycosis fungoides described in children and dark-skinned individuals demonstrates a CD8⁺ epidermotropic infiltrate with a low CD4:CD8 ratio, in contrast to the CD4⁺-predominant T-cell infiltrate found in classic mycosis fungoides.^1,5 Pigment incontinence and melanophages are often seen on light microscopy.¹ A T-cell receptor gene rearrangement may be identified in approximately half of all cases of hypopigmented mycosis fungoides.¹

Postulated mechanisms for the cutaneous hypopigmentation include a defect in melanosome transfer, a nonspecific result of inflammation, and direct cytotoxic effect on melanocytes by T cells.^5,7

Although photochemotherapy using psoralen + UV-A (PUVA) is the treatment option most often described in the literature for hypopigmented mycosis fungoides, other options include narrow-band UV-B, topical steroids, topical nitrogen mustard, topical carmustine, and electron beam therapy.^1- 2 Bexarotene, methotrexate, or pralatrexate may also be used.⁸

The patient was treated effectively with topical steroids and PUVA therapy 3 times weekly, with substantial improvement in all skin lesions after only 2 months of therapy. He is currently receiving maintenance therapy with topical steroids only and will continue to receive close follow-up. His overall prognosis is considered excellent.