The histopathology of lupus erythematosus panniculitis.

Lupus erythematosus panniculitis is a clinical variant of lupus erythematosus in which the main pathologic process involves the deep corium and subcutaneous tissue. We reviewed twenty-nine cases of lupus panniculitis, as well as the cases previously reported in the literature. The histopathologic changes in lupus panniculitis are characterized by a lymphocytic panniculitis, hyaline degeneration of the fat, hyaline papillary bodies, and lymphoid nodular structures in the lower dermis and subcutaneous tissue. Direct immunofluorescence can be important in supplementing the histopathologic study of lupus panniculitis. Lesions of discoid lupus erythematosus are seen in 21% of cases. When this disorder exists in the absence of other typical cutaneous or systemic lesions, the diagnosis of lupus erythematosus has been questioned. We believe that the histopathologic findings of this entity are alone sufficient for a diagnosis of lupus panniculitis, even in the absence of cutaneous or systemic lesions.