Topical 5-fluorouracil treatment of superficial basal cell epithelioma. A light and electron microscopic study

A 27-year-old patient developed superficial basal cell epitheliomas approximately 20 years after taking Fowler's solution. One of the lesions was successfully treated with topical 2% 5-fluorouracil soultion under occlusion. Sequential biopsies of the lesion before, during and after therapy were examined by light and electron microscopy, and the changes at various stages are described. Changes occurred only in tumor cells and adjacent epidermis, and only after occlusion of 5-FU. After one week of occlusive therapy, focal discontinuities in the basal lamina and intercellular spaces were wider with reduction and condensation of tonofilaments. Mitochondrial degeneration was seen along with irregularities in nucleoli. These changes were most prominent after two weeks of occlusive therapy, and many degenerating keratinocytes were seen detached from other cells. One month after cessation of therapy, the entire area was excised, and no evidence of tumor was seen.