6 Ann Rheum Dis 1998;57:6–8 CASE STUDIES IN DIAGNOSTIC IMAGING Series editor: V N Cassar-Pullicino Ann Rheum Dis: first published as 10.1136/ard.57.1.6 on 1 January 1998. Downloaded from Soft tissue mass around the shoulder H S Reid, E McNally, A Carr Clinical history tumours but characteristically arise adjacent A previously fit 47 year old female school to joints and grow slowly. With the exception teacher presented with a six month history of a of PVNS, all these conditions typically show painful swelling over her right shoulder. There some degree of calcification on plain film.1 was rapid development of the swelling initially, Most cases of synovial osteochondromatosis which then stabilised. On examination she was show a pattern of coarse calcification and one apyrexial with a large, firm, non-tender mass third of cases of synovial sarcomas show spotty around the right shoulder, which clinically had calcification.1 Cystic lesions such as a ganglion some cystic features. There was no significant or synovial cyst can occasionally reach this limitation of movement. Other findings on size. clinical examination included some minor soft A lipoma would fit the clinical context but fat tissue capsular swelling of the second and third is of lower density on plain film than muscle metacarpophalangeal joints of the right hand. and consequently would appear blacker on Otherwise the remainder of the locomotor sys- plain film. Other benign neoplasms such as a tem was normal. haemangioma or an angiolipoma could give Her erythrocyte sedimentation rate was this appearance and sarcoma has to be consid- increased at 51 mm 1st h, but C reactive ered. protein remained normal at <0.6. Full blood count was normal with a haemoglobin of 13.4 g/dl, white blood cell count 7.5 × 109 /l, platelet Ultrasound count 424 ×109/l. The rheumatoid factor, how- The ultrasound examination shows that the soft tissue mass is located inferior to the acro- ever, was positive with a titre of 1:1280. http://ard.bmj.com/ mium and deltoid, and superior to the greater tuberosity and supraspinatus tendon. This is Imaging the region of the subdeltoid bursa. It contains QUESTIONS multiple heterogeneous echoes, indicating that (1) What does the plain film (fig 1) show? Sug- it is either a solid mass or a complex cyst. gest a list of diagnoses that would fit this clini- Ultrasound has the advantage of being a cal context. (2) Which of your diagnoses does ultrasound (fig 2) support? on September 28, 2021 by guest. Protected copyright. (3) Describe the magnetic resonance imaging findings (figs 3–5). (4) Using all the evidence what are the most probable diagnoses? Plain film There is a large, homogeneous soft tissue mass superolateral to the right shoulder joint, in the region of the subdeltoid bursa. There is no cal- cification or ossification within the mass. Irregularity of the inferior surface of the acromion and the greater tuberosity suggests some degree of impingement syndrome other- NuYeld Orthopaedic Centre NHS Trust, wise there is no bony or joint abnormality. Oxford The diagnostic possibilities in this case can be divided into those conditions arising from Correspondence to: the synovium of the joint or subacromial bursa Dr H S Reid, NuYeld Orthopaedic Centre NHS and those arising from muscle or related Trust, Windmill Road, tissues. Synovial based lesions such as pig- Headington, Oxford OX4 mented villonodular synovitis (PVNS) can 4LD. present as a soft tissue mass, as can synovial Accepted for publication osteochondromatosis or soft tissue chondro- 22 October 1997 mas. Synovial sarcomas are rare malignant Figure 1 Anteroposterior radiograph of the right shoulder. Soft tissue mass around the shoulder 7 Ann Rheum Dis: first published as 10.1136/ard.57.1.6 on 1 January 1998. Downloaded from Figure 4 Axial T2 weighted image of the right shoulder. Figure 2 Ultrasound showing transverse section through the right shoulder. Figure 5 Gadolinium DTPA enhanced axial T1 weighted image of the right shoulder. the coronal plane in figure 3, appear unin- volved and the rotator cuV intact. DiVerential diagnoses SYNOVIAL STEOCHONDROMATOSIS This is most commonly a monoarticular proc- ess, which presents in the third to fifth decade with a 2:1 male preponderance. The condition Figure 3 Coronal T1 weighted image of the right is thought to be caused by a disorder of the http://ard.bmj.com/ shoulder. metaplasia of the synovial membrane.1 Radio- logically most cases exhibit calcification on the dynamic test and diVerentiation between a plain film and therefore this case would be solid or complex cystic lesion can sometimes atypical. be made by watching the eVect of pressure on its components. In this case, as indeed was suggested clinically, the lesion was thought to PIGMENTED VILLONODULAR SYNOVITIS be a complex cyst, thus favouring the diagnosis This is an unusual proliferative disorder of syn- on September 28, 2021 by guest. Protected copyright. of synovial osteochondromatosis or PVNS. ovium, which typically presents as a non- However, the ultrasound does not definitely painful soft tissue mass arising in the synovial exclude a synovial sarcoma or a liposarcoma lining of joints, tendon sheaths, fascial planes (that is, an extra-bursal lesion). or ligaments. Calcification is not a feature and Fat is characteristically reflective which rein- the ultrasound appearances would be similar to forces the conclusion reached on the plain film figure 2. MRI, however, characteristically that this is not a simple lipoma. shows areas of very low signal on T2 weighted images, which represent haemosiderin deposition.2 Magnetic resonance imaging (MRI) Figure 3, a coronal T1 weighted image, shows gross enlargement of the subacromial subdel- Operative findings toid bursa. The lumen is filled with intermedi- The subacromial bursa was lined by prolifera- ate signal intensity material, which on the T2 tive synovium and filled with numerous loose weighted axial images (fig 4) is seen more bodies (fig 6). clearly to represent multiple filling defects out- Histological examination showed thickening lined by the high signal of fluid within the of the synovial membrane with intimal hyper- bursa. The filling defects themselves are inter- plasia and a heavy subintimal infiltrate of mediate signal on T2 weighting. After gadolin- numerous lymphocytes and plasma cells. Giant ium injection (fig 5) the synovial lining of the cells and lymphoid aggregates were also bursa enhances but no change occurs in the evident in the deeper subintima. appearance of the filling defects. The loose bodies were composed almost Other important points are that the gleno- entirely of fibrin with surrounding organising humeral and acromioclavicular joint, seen in cellular fibrous tissue. 8 Reid, McNally, Carr The precise aetiology of rice bodies remains Ann Rheum Dis: first published as 10.1136/ard.57.1.6 on 1 January 1998. Downloaded from controversial. In the later stages of rheumatoid arthritis, the total synovial surface area is vastly increased by proliferation and hypertrophy of synovial villi. Fassbender et al9 suggest that fibrin accumulates in these villous structures, which then become elongated and snap oV. Popert et al5 argue that it is the precipitation of fibronectin and fibrin, stimulated by the gly- cosaminoglycans released from eroded carti- lage, which is responsible for rice body forma- tion. This theory seems less probable in our case, where the glenohumeral joint was normal both on imaging and at surgery. A further theory, put forward by McCarty and Cheung, suggests that microcirculatory deficiencies within the synovium and conse- quent hypoxia, result in synovial microinfarcts.10 The infarcted fragments then drop oV into the joint cavity and their surface becomes covered by fibrin layers. The final and perhaps most important ques- tion is what is the clinical relevance of rice bodies? It is known that fibrin itself is irritant. Therefore rice bodies themselves have been implicated as one of the stimuli for continuing Figure 6 (A) and (B) Operative findings showing 11 multiple rice bodies. One of the largest fragments contained synovial inflammation. It is certainly true that multiple smaller rice bodies. their eVective removal can produce clinical improvement.5 Glynn has gone a step further to Final diagnosis suggest that persistent fibrin deposits may pro- Multiple rice bodies (fibrin bodies) in the sub- vide a continuous stimulus to antibody forma- acromial bursa caused by rheumatoid disease. tion to other changed body constituents.12 Clinical outcome The patient made a good recovery after the synovectomy and has had no recurrence of her Conclusion symptoms. She has not required any further The imaging characteristics of a huge collec- treatment. tion of rice bodies on plain film, ultrasonogra- phy, and MRI have been demonstrated. http://ard.bmj.com/ Discussion Although uncommon, we suggest that this Rice bodies were originally described by Reise diagnosis should be borne in mind as a diVer- in 18953 in association with tuberculous arthri- ential of atypical synovial ostechondromatosis. tis. They were called rice bodies because of their macroscopic similarity to grains of 1 Madewell J E , Sweet D E. Tumours and tumour-like lesions polished white rice. In 1993 Stein et al4 in or about joints. In : Resnick D. Bone and joint imaging. Philadelphia: W B Saunders, 1989:1185–6. reported a case that first described the MRI 2 Reicher M A. The spectrum of knee joint disorders. In : appearances of subacromial bursitis with mas- Mink J H, Reicher M A , Crues J V, Deutsch A L. MRI of on September 28, 2021 by guest. Protected copyright. the knee. New York: Raven Press, 1993:347–50. sive rice body formation. 3 Reise H . Die Reiskorpchen in tuberculs erkranken synoval- In 1982, Popert et al5 studied the frequency sacken. Dtsch Z Chir 1895; 42:1–99.