Palisaded neutrophilic granulomatous dermatitis, interstitial granulomatous dermatitis and IgA vasculitis associated with incomplete Sjögren's syndrome.

Palisaded neutrophilic granulomatous dermatitis (PNGD) and interstitial granulomatous dermatitis (IGD) are rare granulomatous disorders. Differential diagnosis of PNGD and IGD is often difficult, but both conditions occasionally exist together. We report here the first potential overlapping case of PNGD, IGD, and Immunoglobulin A (IgA) vasculitis associated with incomplete Sjögren's syndrome. An 81-year-old woman who had been followed up for interstitial pneumonia and incomplete Sjögren's syndrome was referred to our clinic. She had multiple erythematous plaques and nodules on her entire body and purpura on her legs. Biopsied specimens showed granuloma formation with neutrophilic infiltration and degenerated collagen fibers in the center. In addition, interstitial granuloma and so-called "floating sign" in the periphery and leukocytoclastic vasculitis were noted. Elastica-van Gieson staining revealed phagocytosis of elastic fibers by multinucleated giant cells around the granulomas. Direct immunofluorescence showed IgM, IgA, and C3 deposition in vascular walls. We made a diagnosis of an overlap syndrome of PNGD, IGD, and IgA vasculitis in a background of incomplete Sjögren's syndrome. No such case has been previously reported. The pathogenesis of the present case may be associated with Sjögren's syndrome.