Melanocyte changes following PUVA therapy

Hyperpigmented Small Spots Induced by Long-Term PUVA Therapy

“…Similar to our findings of cell alterations up to 7 months after the end of the PUVA treatment, Zelickson et al [ 19] found cell degeneration even up to 15 months. However, an interpretation of these results is difficult as very little is known about the life-span of melanocytes and elimination of effete cells [13].…”

“…Our ultrastructural results in the spots essentially correspond to those in the literature on PUVA-treated unspotted patients with respect to the qualitative characteristics [8,19], However, compared with intermacular skin of our patients, many of these alterations occur more frequently in spots. The numerous autophagic vacuoles filled with melanosomes in the spots might represent a mechanism for elimination of surplus pigment [11,18], The degenerative changes of melanocytes vary greatly in nature and extent in the different patients.…”

“…A systemic PUVA treatment, however, causes enlarged melanosomes even in unspotted skin [8,12,19], In our patients these organelles were only slightly elongated in dark skin, and as no structural deviations exist between macules and unspotted surrounding skin, there are no serious hints for a somatic mutation.…”

“…[4] found atypical keratinocytes in clini cally inconspicuous skin. In addition, alterations in the melanocytic sys tem were observed [19], Therefore, clinically visible pigmentary distur bances [2,7,9,11,16] have to be considered with respect to a possible ma lignant transformation. …”

Cutaneous Malignant Melanoma Appearing during Photochemotherapy of Mycosis fungoides

“…On the other hand, in case-control studies, the risk is dif ficult to assess because of the small number of cases. Some data suggest a potential role of PUVA in inducing melano cytic tumors: UVA-activated psoralens interact with DNA [ 19]; PUVA appeared to have a proliferative effect on mel anocytes [5]; melanocytic atypias have been observed in PUVA-induced lentigines and in skin exposed chronically to PUVA [20]; PUVA has immunosuppressive activity [3,4]. Finally, Alcalay et al [21 ] induced a melanocytic tumor in a C3H/HeN female mouse, with repeated topical applica tions of 8-methoxypsoralcn followed by exposure to UVA.…”