Hypopigmented mycosis fungoides: report of five cases with ultrastructural observations.

Five dark-skinned individuals presented with widespread well-demarcated hypopigmented lesions, biopsy of which revealed the histopathological features of mycosis fungoides. Ultrastructural studies showed focal invasion of the epidermis by mycosis cells with degenerative changes in adjacent melanocytes and keratinocytes. The majority of melanocytes exhibited swelling of cytoplasmic organelles and disordered melanogenesis with production of spherical incompletely melanized melanosomes. In addition disintegrating melanocytes were occasionally seen. Perifollicular repigmentation within hypopigmented areas occurred in two patients following clearing of the epidermal infiltrate with PUVA therapy. Mycosis fungoides may present with areas of cutaneous hypopigmentation.