Pseudorheumatoid Nodules in Adults

Abstract

Pseudorheumatoid nodules are considered a deep form of granuloma annulare. Most cases are described in children, occur mainly on the lower legs and scalp, and have favorable prognosis. Their appearance in adults is rare. In this series, fourteen women with pseudorheumatoid nodules were studied. The average age of onset was 36 years old. Lesions consisted of erythematous, violaceous, or skin-colored nodules located mainly on the small joints of the hands. None of the patients developed collagen vascular disease. Persistence was common. Biopsy specimens showed deep dermal nodules composed of epithelioid granulomata separated by thickened collagen bundles. In some areas eosinophilic material was surrounded by histiocytes in a palisaded array. Granuloma annulare was present at the periphery of eight cases. Special stains revealed that most of the eosinophilic material was collagen and mucin was present in eleven cases. In sum these findings demonstrate that pseudorheumatoid nodules in adults are a distinct clinical and pathologic entity, which may be mistaken for rheumatoid nodules. They are probably a juxta-articular variant of granuloma annulare.