Histopathological changes seen in mycosis fungoides patients after phototherapy.

Early stage (IA, IB, IIA) mycosis fungoides (MF) has long been treated with various agents including oral psoralen plus UVA (PUVA), broadband and narrowband. The histopathological changes seen after phototherapy have not been clearly described. Twenty-three skin biopsy specimens of MF patients treated with phototherapy both UVA and UVB were evaluated before and 3 months after phototherapy. The clinical and histomorphological response were evaluated. Various types of epidermotropism: such as single cells, haloed cells, linearly arranged single cells, pagetoid spread, and Pautrier microabscesses were noted. Stratum corneum was classified as normal, hyperkeratotic, and parakeratotic. The epidermal thickness was noted as normal, atrophic, and hypertrophic. Spongiotic microvesiculation, presence of dilated dermal vessels, was investigated. Papillary dermis fibrosis, the presence of plasma cells, eosinophils, and extravasated erythrocytes were also examined. Epidermal hyperplasia, dermal fibrosis, loss of parakeratotic pattern, and inflammatory infiltrate were frequently observed after therapy. After phototherapy, the atypical cells rarely formed "Pautrier microabscess" or made a "linear pattern" at the base of epidermis. The cells other than lymphocytes (plasma cells, eosinophils, and erythrocytes) should also be considered regarding the phototherapy effect. A pathology report of a MF patient who has undergone successful phototherapy would describe changes resulting from phototherapy-such as fibrosis or "lack of dermal inflammation" and the absence of active epidermal cellular changes such as "Pautrier microabscess" or "linearly arranged cells."