Interstitial granulomatous dermatitis with plaques and arthritis.

Interstitial granulomatous dermatitis (IGD) is a histopathological disorder characterised by an infiltration of the reticular dermis with a predominance of interstitial and palisadic histiocytes with a few areas of degenerating collagen bundles associated with a variable number of polynuclear neutrophils and eosinophils. There are several clinical conditions with a pattern of IGD. The linear form associated with arthritis was the first variety described. There is also a second form, which presents with plaques. This variety may be associated with arthritis, use of certain drugs or the presence of different systemic disorders. We report a case of IGD with plaques and arthritis. We discuss the differential clinical and histological diagnosis with other inflammatory skin lesions, which may be associated with joint disorders and collagen degeneration. We believe that it should be considered in patients presenting with arthritis and skin lesions.