Abstract
A child with shoulder pain and great palpable mass without any injury history is an emergent case until the diagnosis is confirmed. We report the clinical findings, imaging features, surgery and histological analyses of primary synovial chondromatosis in glenohumeral joint, biceps tendon sheath and subcoracoid bursa in a child, aged 14. Primary synovial chondromatosis is characterised by multiple calcified nodules in joints, tendons or bursa areas. The condition is more usual in large joints, in particular in lower extremities. It may be symptomless until the volume of chondromatosis has increased to such an extent that it results in pain, locking symptom or palpable mass. The treatment is removal of the loose bodies and potentially synovectomy, in means of open or arthroscope-assisted surgery. Postoperative follow-up is recommended due to the risk of recidivism and potential malignant transformation. The disease is more common in older patients and there are only isolated cases in pediatric population.
Keywords: Synovial chondromatosis, Primary synovial chondromatosis, Shoulder pain, Palpable mass
1. Introduction
A palpable mass in large joint surroundings in a pediatric patient is a concern for parents, children and clinicians. Primary synovial chondromatosis (PSC) is a benign cause of monoarticular palpable mass.1,2 It may decrease the movements and manifest as an area of tenderness. Radiographic findings are usually clear, but the loose intra-articular nodules mimic the “rice-bodies” found in secondary chondromatosis in adult patients. Magnetic resonance imaging (MRI) is important for the exclusion of solid tumors. Potential differential diagnoses are osteosarcoma, chondrosarcoma and Ewing’s sarcoma.3 Synovial sarcoma is the most common soft-tissue sarcoma in children and 90% of them occur in the extremities. Of benign tumors, osteochondromas, simple and aneurysmal bone cysts and enchondromas are the most common in shoulder.3
There is minimal literature concerning the primary synovial chondromatosis of glenohumeral joint and biceps tendon sheath in pediatric population.4, 5, 6, 7 We report a large tumor in a child, aged 14, and review the current practice.
2. Patient
A boy, aged 14, had suffered from pain and stiffness in his left shoulder for one year. He was a junior ice-hockey player but no single high-energy injury had occurred to him. The symptoms had slowly increased and were associated with physical activities. During the last few weeks prior to admission, a palpable mass on the shoulder was noticed by the patient and his parents. The patient had no general illness and no family-history of joint disorders.
No erythema, eczema, excoriation, bruise or soft-tissue swelling were found. The shoulder area was tender on palpation. Shoulder movements were full. The joint was stable. The clavicle, acromio-clavicular joint and humerus were normal.
Anterior-posterior radiographs were first taken. Massive intra-articular tumor with a height of approximately 75mm was found and it comprised a great number of small calcified nodules. The density of calcification of these nodules varied between subtle and great and they varied in size (Fig. 1). In contrast, no focal bone lesions or erosion were seen in the humerus or scapulae. Magnetic resonance imaging was performed: loose bodies were contoured by the joint capsule but they extended to the subscapular recess and biceps tendon sheath. There were no neovascular structures in the particles. Synovia was normal.
Fig. 1.
A previously health boy, aged 14, suffered from palpable mass and tenderness of the shoulder. A) Radiographs showed large focal area of nodular calcification around the glenohumeral joint. The joint structures were intact. B) Magnetic resonance imaging revealed multiple centers of nodular calcification and similar findings within the biceps tendon sheath. There was no excess of synovial joint fluid and no focal bone disease in the humerus or scapulae.
A multi-disciplinary team assessment concluded that intra-articular tissue would be resected without a previous biopsy, and deltopectoral approach was used for arthrotomy. The clavipectoral fascia was incised and the subscapularis tenotomized. A high number of pure white, round, shiny and solid loose bodies were removed from the joint, including the inferior recess and the subcoracoid bursa area as well as the biceps tendon sheath. The total volume of the tumor nodules was approximately 25 ml (Fig. 2). Upon removing the particles, the synovial tissue, bursas and cartilages were examined thoroughly and no irritation or disease was found.
Fig. 2.
A) Deltopectoral approach was used and the loose bodies were removed from the joint and tendon sheath and subcoracoid bursa area. B) The synovial chondromatosis nodules changed in size but were between 2 and 10 mm in diameter. C) The total volume of the removed chondromatosis was approximately 25 ml.
For the histopathological analysis, the specimens were fixed in 4% formalin and embedded in paraffin blocks. All particles were hard and the hardest of them required EDTA (Ethylenediaminetetraacetic acid) decalcification for adequate sectioning. The tissue blocks were sliced and 4 μm thick sections were stained with a routine hematoxylin and eosin staining. Histologically, the samples showed lobulated areas of mature hyaline cartilage covered by a layer of fibrosis with occasional hyalinization, and regionally a surface resembling synovial surface. The cartilage was largely calcified, partly ossified. The chondrocytes had small nuclei, showed no atypia, and were usually arranged in clusters. There were no malignant characteristics (Fig. 3).
Fig. 3.
The histological findings. A) In an overview, the removed particles have relatively smooth contours and a layer of pink fibrous tissue with low cellularity on the surface. B) and C) are higher magnifications of the areas marked with the rectangles in A). The cellular density in cartilage is variable, but the chondrocytes have small nuclei and show no atypia. They are often arranged in clusters. There is some calcification, visualized by the intensive purple staining. Scale bars depict 500 μm.
The shoulder was symptomless and the patient returned to his previous recreational activities in eight weeks. He was completely recovered at the one-year mark, without signs of recidivism.
3. Discussion
Primary synovial chondromatosis is a benign and idiopathic disease of the synovial tissue with formation of osteochondral nodules. Radiographic “rice-body” findings may be similar to those in secondary chondromatosis in older patients. However, it is important to recognize pediatric chondromatosis as separate condition. Previous repeated mechanical stress against the affected joint and inheritance characteristics have been suggested as predisposing factors.8 The disorder is more common in large joints. To date, only few cases concerning the shoulder have been reported in pediatric population.
The symptoms are unspecific, often resulting in delays in diagnosis. Later, pain during exercise, locking symptoms and palpable mass may occur, when the volume of the chondromatosis increases. The radiographs are not specific but the findings are usually characteristic. There are three stages in the disease. Stage 1 is an active intrasynovial disorder without the presence of loose nodules and thus not seen in radiographs. Stage 2 is a developing stage and stage 3 refers to multiple intra-articular loose particles without intrasynovial disease.9 The disease is detectable by radiographs since stage 2, but MRI allows visualization of uncalcified lesions or synovial tissue disorder in the stage 1. MRI also aids in planning the operation and choosing between different surgical approaches.
Potential differential diagnoses are synovial chondrosarcoma, usually not seen within the synovial cavity, and other synovial proliferative diseases such as pigmented villonodular synovitis.10 Traumatic osteochondral fragments and osteoarthritis dissecans are distinguished by MRI.
Operative treatment relieves the symptoms. When loose intra-articular findings are found instead of solid tumor in comprehensive imaging, preoperative biopsy for histology may not be indicated. However, the tissue sample should always undergo histopathological analysis, as malignant transformation may occur in 5%.2 Open surgery is a traditional technique, while limited space is available for arthroscopy.4,5 Partial synovectomy is optional and recurrence rate has been suspected to be lower after synovectomy. However, it may be hard to find and determine the affected area for synovectomy, when operating at the later stage. For this reason partial synovectomy was not performed in our case either. Recurrence rate may be up to 15% despite the treatment.11 This justifies a follow-up with MRI for two years.
As a conclusion, we presented a pediatric patient with massive primary synovial chondromatosis in the shoulder and biceps tendon sheath. This uncommon disease needs to be recognized and treated due to its risk of malignant transformation. The disease should not be confused with secondary chondromatosis, which is usual in adults.
Funding
This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.
Declaration of competing interest
The authors declare that there is no conflict of interest.
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