To the Editor.—
The thrust of Dr. Holmes' letter is that formalin pigment, contrary to its classical definition as an iron-free derivative of hemoglobin,1 actually contains iron, demonstrable by bleaching for ten minutes in 3% hydrogen peroxide followed by staining with Prussian blue. Using this method, we were unable to corroborate Dr. Holmes' finding of iron in formalin pigment. The procedure was performed on formalin pigment, induced in skin, spleen, and placenta, in two separate pathology laboratories of the University of Miami (Fla) School of Medicine (Jackson Memorial Hospital and Mount Sinai Hospital). In both laboratories, formalin pigment remained unstained by Prussian blue after exposure to 3% hydrogen peroxide for ten minutes.We trust that other pathologists, prompted by Dr. Holmes' thought-provoking letter, will search for iron in formalin pigment and will explore further its still obscure nature.
Ackerman AB, Penneys NS. REMARKS ON FURTHER PROPERTIES OF FORMALIN PIGMENT-Reply. Arch Dermatol. 1971;103(5):566. doi:10.1001/archderm.1971.04000170099029