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Case Reports

Abstract

Extra-articular manifestations of Rheumatoid Arthritis (RA) affect approximately 40% of patients with rheumatoid nodules (RNs) being among the most common, particularly in seropositive individuals. RNs typically affect patients with established joint disease, and only limited case reports have documented patients with RNs prior to the onset of arthritis. Further, the presence of RNs at diagnosis have been correlated with disease severity. Here, we present a case of a patient without a personal history of autoimmune disease who developed an elbow papule resembling an adnexal tumor or cyst. On histopathologic examination, the tissue exhibited palisaded granulomatous dermatitis in conjunction with dermal mucin and negative infectious stains. The histology also closely mimicked granuloma annulare; however, the localization of the mucin to the periphery of the granulomata in addition to the eosinophilic, focally homogenous, necrobiosis was more consistent with an RN. On clinical follow-up, the patient developed oligoarticular arthritis and morning stiffness with laboratory studies demonstrating elevated CRP, ESR, RF and CCP, culminating in a diagnosis of seropositive RA. In a patient with no personal history of autoimmune disease, the diagnosis of an RN must be balanced against other likely diagnoses on the histologic differential. This case highlights the diagnostic importance of recognizing RNs in the rare circumstances of patients without overt RA even when the clinical impression is that of a mass or neoplasm. Early identification of RNs in these patients may expedite evaluation, prognostication, and management of a disease with numerous morbid sequalae.