International Academy of Cosmetic Dermatology
Histopathology refers to the examination of the tissue sections to establish or confirm a diagnosis. Once a skin lesion has been removed, either completely or partially, the biopsy specimen is placed in a formalin solution and transported to the laboratory.
Processing of the tissue for permanent sections includes three stages: dehydration, clearing, and infiltration. Dehydration removes water from the specimen by passing the tissue through increasing concentrations of ethanol. Clearing permits extraction of the lipids and removal of the alcohol by passing the tissue through xylene. Infiltration with hot, melted paraffin, enables the tissue to be stabilized for cutting.
Thin sections of the paraffin-infiltrated tissue are cut and transferred to glass slides. The tissue is usually stained with hematoxylin and eosin (H&E). Special stains are occasionally used, when particular features need to be demonstrated.
After a mounting solution and a coverslip are applied, the tissue specimen is ready for microscopic evaluation.
Philip R. Cohen, MD
Bellaire, TX, USA