As with all iron solutions applied to dermal surfaces denuded of epithelium or to mucous membranes, topical application of AstrinGyn® (ferric subsulfate) may result in hyperpigmentation (“tattooing”).3, 4
Microscopically, this hyperpigmentation may be observed as ferrugination of collagen fibers and fibrin.5 In one study of uterine cervical tissue, ferric subsulfate solution penetrated denuded mucosa and produced coagulation necrosis to a maximum depth of 0.6 mm.6In an in vitro study, ferric subsulfate solution produced a radiopacity with a density intermediate between that of water/tissue and calcium.7Should a re-biopsy of the same lesion be required, pathologists and other physicians involved in the care of the patient should be aware of the previous use of ferric subsulfate solution. Previous use of ferric subsulfate solution may result in a histologic artifact upon re-biopsy of heavy pigmentation, similar to hemosiderin, together with shrinkage and discoloration of collagen bundles.8, 9 Similarly, previous use of ferric subsulfate solution may result in a radiographic artifact.