Information on the skin biopsy
Selecting the biopsy technique
Biopsy of panniculitis
When panniculitis is suspected, the biopsy technique will depend on the site of the inflammation locus. If the dermis is thin, as for example at stretching sides of the shank, a 6mm punch biopsy may be performed. The large diameter of the punch is required because both septa as well as lobula of the fatty tissue must be assessed for the histopathological diagnosis of panniculitis. Compared with the spindle biopsy, the punch biopsy has the advantage that it is easier to carry out and heals with a smaller scar. In addition, it frequently yields a preparation that is easier to assess, since, when a spindle biopsy is used, they quite often tend to be performed inwards, and consequently record only a small amount of fatty tissue. After carrying out a fatty-tissue biopsy, the operator must always be satisfied that sufficient fatty tissue is present at the lower edge of the biopsy.(4) When there is a thick dermis, as for example at the thigh and the back, a spindle biopsy should in all cases be performed using the scalpel. Spindle biopsies should thus be performed as a matter of principle when focal changes in the fatty tissue are vital for diagnosis, but which appear for the first time only following numerous graded incisions, such as for example a vasculitis when there is suspected panarterritis nodosa or Erythema induratum.