A histochemical test for citrulline daptation of the carbamido diacety reaction to histologic sections with positive results in pilomatrixomas (calcifying epitheliomas).

Abstract

Slight quantitative differences exist in the chemical composition of various components and sheaths of the hair follicle. The one qualitative difference which has been found is the unique presence of the amino acid, citrulline, in the inner root sheath. Citrulline accounts for 6.1% of the dry weight of the sheath. In the past, Ehrlich's p-dimethyl aminobenzaldehyde reagent has been used to detect citrulline in the inner root sheath both chromatographically and histochemically. The histochemical color is a faint yellow and tryptophan interferes also, giving a positive reaction. A more specific test is given by Fearon's diacetyl monoxime reagent which reacts in hot acid solution with carbamido compounds. In the present investigation the carbamido diacetyl reaction was adapted for histochemical study by use of a silicone rubber adhesive for tissue sections that would withstand boiling hydrochloric acid. The reaction colors the inner root sheath a bright orange and when applied to pilomatrixomas is positive in some of the keratinous areas.