Presentation
Known rheumatoid arthritis on treatment with methotrexate. Large masses affecting ability to wear shoes.
Patient Data
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Two subcutaneous nodules, intimately related to the Achilles tendon. PD fat sat and T1 demonstrate heterogeneous subcutaneous masses abutting but not arising from the Achilles tendon i.e. the paratenon. Note there is also heterogeneous enhancement with minimal reactive edema and no signal change within the tendon.
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Clinical photograph and corresponding oblique reformat T1 fat sat MRI image showing the 2 subcutaneous nodules, intimately related to the Achilles tendon.
Case Discussion
Rheumatoid nodules are subcutaneous masses occurring in rheumatoid arthritis, usually at sites of repeated trauma, e.g. hands and elbows but also ankles, and often in patients being treated with methotrexate. They are usually non-tender but can interfere with manual activities and may become ulcerated by rubbing e.g. against the heels of shoes, leading to ulceration and bleeding. Medical treatment is often not successful so intralesional steroid injection or excision may be necessary.
Histologically, they are composed of central fibrinoid necrosis surrounded by a palisade layer of histiocytes and a peripheral zone of loose connective tissue.