Reappraisal of histopathology of cutaneous polyarteritis nodosa.

BACKGROUND: There is controversy on whether lymphocytic thrombophilic arteritis (LTA) and macular arteritis (MA) are a different entity from cutaneous polyarteritis nodosa (C-PAN).

OBJECTIVE: To evaluate the controversy on LTA/MA by examining the morphologic changes during the dynamic inflammatory process.

MATERIALS AND METHODS: A clinical and histopathological investigation of 46 biopsy specimens from 21 histopathologically proven C-PAN patients at our hospital was performed.

RESULTS: Most of the biopsy findings revealed arteritis in the subacute and reparative stages. Coexistence of different stages was found in over half of the specimens. Two biopsy specimens consistent with LTA/MA showed coexisting histologically proven (subacute stage) C-PAN in other lesions. Analyses of the longitudinal sections showed focal and segmental arteritis. Patients overall improved well with compression stockings, anti-inflammatory agents, a prostaglandin analog and antiplatelet agents. Currently, three patients are medication free and only require compression stockings.

CONCLUSION: LTA/MA seems to be part of the spectrum of C-PAN. The vasculitic lesions of C-PAN are segmental and focal, and coexist in different stages. As the chronic stage of C-PAN can be mistaken as LTA/MA, it is necessary to perform multiple biopsies, serial sections and analyses of longitudinal sections to confirm the main finding of vasculitis.