A giant rheumatoid nodule

Solitary subcutaneous sarcoidosis with massive chronic prepatellar bursal involvement

A 56-year-old man presented with a painless prepatellar mass of the left knee. MR images demonstrated a large, well-defined mass with heterogeneous intermediate signal intensity on T1- and proton density-weighted images. Mild, heterogeneous enhancement was noted after the intravenous administration of gadolinium. Diagnostic imaging included atypical soft-tissue infection, fibrogranulomatous reaction, gouty tophus, rheumatoid nodule and xanthoma or possibly malignancy. The histopathological examination revealed sarcoidosis involving the prepatellar bursa.

MRI appearance of retrocalcaneal bursitis and rheumatoid nodule in a patient with rheumatoid arthritis

Rheumatoid arthritis is an autoimmune disorder of unknown etiology characterized by symmetric, erosive synovitis and sometimes multisystem involvement. Rheumatoid nodules have been reported in as many as 20-30% of patients with rheumatoid arthritis; however, they are not commonly seen in the feet. We present magnetic resonance (MR) findings of a rarely seen case of rheumatoid bursitis in the retrocalcaneal bursa associated with a subcutaneous rheumatoid nodule inferior to the calcaneus which histologically confirmed the rheumatoid arthritis. To the best of our knowledge, this is the first case that rheumatoid bursitis in the retrocalcaneal bursa associated with the rheumatoid nodule in the foot was revealed by MR imaging.