For skin biopsies fixative?

• A. Bouin's
• B. Mercuric chloride
• C. Heidenhain's Susa
• D. Carnoy's

Answer: (C)

Selecting a fixative for skin biopsies hinges on preserving the delicate architecture of the epidermis and dermis, including hair follicles, sweat glands, and the dermo-epidermal junction, with minimal shrinkage and artifact. Heidenhain's Susa is a multi-component fixative that provides excellent preservation of tissue morphology and nuclear detail while cross-linking proteins in a way that keeps delicate dermal structures intact. It also preserves glycogen and mucopolysaccharides well, which can aid in certain stains and overall tissue appearance.

In contrast, Bouin's fixative, although good at preserving some cellular details, tends to cause strong tissue distortion and leaves a yellow pigment from picric acid that requires washing; Carnoy's fixative is even harsher, causing significant shrinkage and lipid extraction; mercuric chloride is effective but toxic and less desirable for routine skin histology. Among these options, Heidenhain's Susa offers the best balance of morphology preservation and stain compatibility for skin biopsies.