^{1, 2, 3}Suad Hannawi, ¹Haifa Hannawi, ³Maria Al-Salmi

¹Al Kuwait-Dubai (Al Baraha) Hospital, Emirates Health Services (EHS), ²Ministry of Health and Prevention (MOHAP), Dubai, ³Medical and Health Sciences, Sharjah University

Purpose Statement: Rheumatoid nodules are the most common cutaneous manifestation of rheumatoid arthritis (RA) that can be seen in about 25% of RA patients and are found mostly in subcutaneous regions subject to recurrent mechanical stress.

On the other side, the ganglion cyst starts when the fluid leaks out of a joint or tendon tunnel and forms a swelling beneath the skin. The cause of the leak is generally unknown but may be due to trauma or underlying arthritis.

The key difference between an RA nodule  and a ganglion cyst is that a ganglion cyst is a small, soft, fluid-filled lump that occurs under the skin and is not associated with any medical condition, while an RA nodule is a large, firm lump that occurs under the skin and is usually associated with RA.

Rheumatoid nodule is most often seen in patients with seropositive RA and more severe disease. However, there is no evidence that systemic therapy treats rheumatoid nodules, and treatment of rheumatoid nodules is often not necessary.

Method(s): We are presenting a case of an asymptomatic patient with a dorsum subcutaneous nodule that had been suspected of as ganglion. Histology proved the mass an RA nodule. RA symptoms followed after years.

Result(s): Indian, 60-year-old male, who is not known to have any medical problems before. Presented to the orthopedic clinic with a small mass at the dorsum of the right hand that appeared over a few days (Figure 1, and Figure 2.). The mass was a lump of 3×2 cm with a defined border, mobile, and no tenderness. The skin over the cyst looks normal and feels smooth, round, and rubbery. Despite the small mass of the cyst and the presence of no symptoms, the patient wanted to remove the mass for cosmetic reasons.

Excision was done surgically and the mass was sent for histological examination as a routine practice in the hospital for any surgically excised sample. The histology results revealed macroscopically a specimen consists of multiple grey-white soft tissue bits altogether measuring 3x2x0.5 cms

Microscopic examination showed a section with synovial tissue with villous hyperplasia of synovium. The villi are lined by multilayered synoviocytes. There were areas of fibrinoid necrosis surrounded by a palisade layer of histiocytes. The stroma shows extensive vascular proliferation with a focal collection of lymphocytes. Occasional fragment shows fibrinoid necrosis of the vessel wall with lymphoid aggregation, as well as areas of fibrosis. The histology report concluded with the impression that histopathological features are suggestive of rheumatoid arthritis nodules.

Based on the histological findings the patient had been referred to the rheumatology clinic of Al Kuwait-Dubai (Al Baraha) hospital for further evaluation for any possible clinical RA. Detailed history and physical examination did not reveal any musculoskeletal manifestation. Laboratory tests revealed normal complete blood count, inflammatory markers (Erythrocyte sedimentation rate and C-reactive protein), and, renal and liver function. The immunology profile revealed negative rheumatoid factor and anti-citrullinated peptide, ANA, and ENA. Based on the absence of evidence to treat rheumatoid nodules the patient was discharged with advice to attend if any new symptoms emerge.

After 13 months, the patient presented again with typical swelling and pain in the joints of the fingers. Examination revealed arthritis (swelling, hotness, and redness) of metacarpophalangeal joints (MCPJs) and proximal interphalangeal joints. Squeeze tests were positive with a tenderness of MCPJs. Repeated blood tests showed normal complete blood count, and renal and liver function. The immunology profile revealed negative rheumatoid factor and anti-citrullinated peptide, ANA, and ENA. But, the high ESR is 65 mm/hr., and the CRP is 42 mg/dl. The patient was diagnosed with RA based on the American College of Rheumatology/European League Against Rheumatism (ACR/EULAR) criteria for RA classification 2010.

Although Methotrexate could increase the rheumatoid nodule, it was the first option of treatment. 15 mg Qwk had been started. Assessment in 3 months the patient came back with no joint pain, swelling, or tenderness, with normal inflammatory markers.

Conclusion(s): A suspected ganglion in a symptomatic subject might need a thorough medical history, medical examination, and laboratory investigation to rule out rheumatoid arthritis.