Which fixative is preferred for skin biopsies?

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

Answer: (C)

Fixation quality directly shapes how skin architecture and cellular detail appear under the microscope. Heidenhain's Susa provides gentle, thorough preservation of epidermal and dermal structures, including the basement membrane and connective tissue framework, with excellent nuclear and cytoplasmic detail and minimal artifact. It yields crisp, morphologic detail that is crucial for accurately evaluating skin biopsies, while avoiding excessive shrinkage or overstaining that can come with other strong fixatives. Bouin's fixes well in some respects but introduces a yellow picric acid pigment and often requires extensive washing; Carnoy's is very rapid and can cause tissue shrinkage and distortion; mercuric chloride is highly toxic and can leave heavy metal artifacts and is not ideal for routine use. Thus, Heidenhain's Susa stands out as the preferred option for skin biopsy fixation.