SYNOVIAL CYST OF THE SHOULDER JOINT IN THE BICIPITAL AREA IN JUVENILE RHEUMATOID ARTHRITIS

Masafumi Homma, M.D.,D.M.Sc, Research Fellow of Orthopaedic Surgery

William G. Mackenzie, M.D.,FRCS(C), Attending of Pediatric Orthopaedic Surgery

July 26, 1995

CLINICAL CASE PRESENTATION

ORTHOPAEDIC DEPARTMENT

THE ALFRED I. DUPONT INSTITUTE

WILMINGTON, DELAWARE

CASE HISTORY:

• HISTORY: This is a 7 year old girl who has had polyarticular JRA for over a year. Most recent management has been with prednisone, methotrexate and tolectin. The symptoms improved with little evidence of ongoing synovitis. A mass in the left bicipital area was first noticed at the age of 7 years and 9 months.
• PHYSICAL EXAM: The mass was firm, located in the antero-medial aspect of the left upper arm and was difficult to separate from the biceps. It did not transilluminate. Shoulder ROM was full.
• SONOGRAM AND XRAYS: The sonogram showed a solid soft tissue mass which was fairly homogeneous in echo-genicity, and well defined with minimal vascularity. No connection with the shoulder joint was observed. MRI with gadolinium showed a mixed density collection which appeared to have a narrow connection with the shoulder joint. An arthrogram of the left shoulder joint demonstrated extension of dye down the bicipital groove and into the mass in the upper arm. The mass was more palpable after the arthrogram. We concluded that the mass was a synovial cyst due to chronic synovitis.
• FOLLOW-UP: The synovial cyst has resolved spontaneously and has not recurred over 3-months follow-up.

DISCUSSION:

In this case, the synovial cyst was noticed while the synovitis was well controlled atypical for synovial cysts. Several factors made the diagnosis difficult in this case. The clinical findings and ultrasound suggested a solid tumor. Sonography of a synovial cyst filled with proteinaceous material would show intermediate signal intensity, so that it may be confused with solid tissue mass. MRI was useful in this case in suggesting a connection between shoulder joint and the mass but this connection may not always be seen. An arthrogram may be indicated in similar cases prior to surgical intervention such as needle or open biopsy. Synovial cysts should be considered in the differential diagnosis of upper extremity soft tissue tumors in children with JRA.

REFERENCES:

1. Towner SR, Micher CJ, Jr,O'Fallon WM et al: The epidemiology of juvenile arthritis in Rochester, Minnesota. Arthritis Rheum 26:1208,1983.
2. Bamzai A, Krieger M, Kretschmer RR: Synovial cysts in juvinile rheumatoid arthritis. Ann Rheum Dis. 37:101-3,1978.
3. Costello PB, Kennedy AC, Green FA: Shoulder joint rupture in juvenile rheumatoid arthritis producing bicipital masses and a hemorrhagic sign., J Rheumatol. 7: 563-6,1980.
4. Rennebohm RM, Towbin RB, Crowe WE, et al.: Popleteal cysts in juvenile rheumatoid arthritis. AJR.140:123-5,1983.
5. Soslow AR: Popliteal cysts in a pediatric patient. Ann Emerg Med 16: 588-91,1987.
6. Cassidy JT, petty RE: Textbook of pediatric rheumatology, Churchil Livingstone, New York,1982.
7. Melvin JL: Rheumatic disease in the adult and child, F.A. Davis company, Philadelphia, 1989.