New population of amelanotic spindle cells are clearly demonstrated in vitiliginous skin after ultraviolet radiation.

Background: Phototherapy is a well-known method to treat vitiligo and is able to repopulate the skin with new melanocytes. Examination of the pathological changes in vitiligo after ultraviolet therapy revealed the presence of unusual cells.
Aim of Study: This study intended to investigate and confirm the repopulation of epidermis with new spindle cells, possibly as precursors for melanocytes after UV therapy.
Methods: Retrospective study was carried out on paraffin sections of biopsies obtained from 30 vitiligo patients treated successfully with ultraviolet therapy. Routine, special and immune staining were utilized to examine these biopsies.
Results: Amelanotic spindle cells with slightly eosinophilic cytoplasm and dark flattened nuclei were characteristically demonstrated in all examined sections after ultraviolet therapy. These cells were abundant near infundibular portion of hair follicles. They subsequently developed dendrites and became melanized.
Conclusions: Melanocyte precursors can be demonstrated pathologically and immunologically on tissue samples after ultraviolet therapy. They are capable of proliferation and migration into depigmented epidermis to repopulate it with new generations of melanocytes.
(© 2013 European Academy of Dermatology and Venereology.)