De histopathologie van panniculitis

Panniculitis can be defined as a heterogeneous group of disorders characterized by inflammatory changes primarily involving the subcutaneous fat. Clinicopathological correlation is crucial for a specific diagnosis since different panniculitides show the same clinical appearance, presenting as erythematous nodules on the lower extremities. Traditionally, panniculitis has been viewed as a challenging group of disorders in dermatopathology which is mainly caused by inadequate sampling. A deep incisional biopsy that extends through the subcutaneous fat taken from an early lesion is the ideal specimen for assessment of panniculitis. Also insight into the pathogenesis of inflammation in the different types of panniculitides, is crucial for understanding these conditions. A stepwise histological approach by evaluating the following will lead to a specific diagnosis in most cases: (1) primary dermatitis or primary panniculitis, (2) mostly lobular or mostly septal panniculitis, (3) presence of vasculitis, (4) the predominant inflammatory cell type and (5) presence of additional histological clues. In this article the prototype of the most common types of panniculitides are discussed. The prototype of a mostly septal panniculitis without vasculitis is erythema nodosum, of a mostly septal panniculitis with vasculitis is polyarteritis nodosa, of a mostly lobular panniculitis without vasculitis is lupus panniculitis and of a mostly lobular panniculitis with vasculitis is erythema induratum/nodular vasculitis.