Information on the skin biopsy

The basis of dermatopathology

Histopathological assessment

When there are neoplasias, it is primarily a question of judging its biological behaviour; in other words, distinguishing between the benign and the malign. This is best done by assessing its growth pattern. As criteria such as demarcation, symmetry and configuration of tumour cells directly reflect the biological behaviour of a neoplasia, they are more meaningful than other changes such as atypical nuclei and mitoses.(3) A good example of the merit of distinguishing criteria is the pointed birthmark, which was classified as a malignant melanoma despite marked atypical nuclei. Only later, once the shape of the birthmark is noted – its symmetry and sharp demarcation – was the good prognosis clarified, and a reliable demarcation from melanoma was possible. Neopolasia biopsies should therefore always make it possible for the histopathologist to form an impression of the overall structure of a lesion.

The same applies to inflammatory dermatoses: diagnosis depends critically on the assessment of infiltrating cells in the epidermis, dermis and sub-cutis. Most often we find peri-vascular infiltrate, which is confined to the upper half of the dermis (medications and virus exanthema, purpura pigmentosa progressiva, secondary lichen, etc). If the inflammation infiltrate extends also to the deep-vessel plexus located at the edge of the sub-cutis, then consideration must be given to the possibility of entirely different diseases in differential diagnosis; for example lupus erythematosus. When there are inflammatory processes in the sub-cutis, the question arises whether the changes affect predominantly the septum, as in erythema nodosum, or the lobulus of the fatty tissue, as is generally the case in erythema induratum and Lupus erythematosus profundus.(4) If the relevant skin and fatty tissue areas are not captured representatively by the biopsy, it is frequently impossible to make any confident histopathological diagnosis.

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