Case report 460: Synovial chondrosarcoma of left knee

Malignant Transformation of Synovial Chondromatosis: A Systematic Review

Background:

Synovial chondromatosis (SCh) can undergo malignant transformation. Pathologic diagnosis of secondary synovial chondrosarcoma (SChS) is challenging and misdiagnosis may result in over- or undertreatment.

Method:

A systematic review revealed 48 cases of SChS published in 27 reports since 1957. Data was collected to identify findings indicative of SChS and outcomes of treatment.

Results:

At median follow-up of 18 months, patients were reported as alive (10%), alive without disease (22%), alive with disease (15%), dead of disease (19%), dead of pulmonary embolism (4%), and unknown (29%). Initial diagnosis of SChS (grade: low/unknown 48%, intermediate/high 52%) was after biopsy in 58%, local resection in 29%, and amputation in 13%. Seventy-four percent of patients underwent 1.8 (mean) resections. Patients treated prior to 1992 were managed with amputation in 79% of cases compared to 48% after 1992. Symptoms were present for 72 mos prior to diagnosis of SChS.

Synovial chondrosarcoma demonstrated symptom progression over several months (82%), rapid recurrence after complete resection (30%), and medullary canal invasion (43%). The SChS tumor dimensions were seldom quantified.

Conclusion:

Malignant degeneration of synovial chondromatosis is rare but can necessitate morbid surgery or result in death. Pathognomonic signs for SChS including intramedullary infiltration are present in the minority of cases. Progression of symptoms, quick local recurrence, and muscle infiltration are more suggestive of SChS. Periarticular cortical erosion, extra-capsular extension, and metaplastic chondroid features are non-specific. Although poorly documented for SChS, tumor size is a strong indicator of malignancy.

Biopsy and partial resection are prone to diagnostic error. Surgical decisions are frequently based on size and clinical appearance and may be in conflict with pathologic diagnosis.

Synovial chondrosarcoma

BACKGROUND

Synovial chondrosarcoma (SCH) is a very rare tumor arising in the intra-articular cavity. In the majority of literature reports it is described as a malignant transformation of a pre-existing synovial chondromatosis (SC). We reported a systematic review of primary and secondary SCH described in the literature with the aim to recollect data from different case-reports and case-series, trying to summarize general aspects of this very rare disease.

METHODS

We collected 42 abstracts in the form of case series and case reports, which reported 67 cases of SCH. Studies were taken into account only if they proved a histological diagnosis of SCH, either primary or secondary, with or without evidence of pre-existing SC.

RESULTS

The average age of SCH was 56.9 years, with prevalence for male sex. The average time of malignant transformation was 11.2 years. The most affected joint was the knee (47.7%), followed by hip (34.3%) and ankle (5.9%). SCH was described as de novo sarcoma only in 13 cases (19%). Surgery ended up with amputation in 59.7% of cases. Local recurrence rate was 28.3%.

CONCLUSIONS

We concluded that prognosis of SCH is worse than conventional one and we speculated this is due to the difficult site of the tumor (intraarticular), diagnostic delay and inappropriate previous treatments. We consider that a rapid deterioration of a SC or rapid recurrence after synoviectomy should be considered suspicious of malignant transformation and should be treated in a reference center.

Primary intra-articular sarcoma: a clinicopathological study of 15 cases

AIMS

To assess the clinical and histopathological spectrum of primary intra-articular sarcomas.

METHODS AND RESULTS

Fifteen patients were identified as having primary intra-articular sarcomas and the clinical and pathological features were evaluated. There were nine males and six females who ranged in age from 16 to 84 (mean 44) years. All tumours originated in the knee joint. The pathological diagnoses included: five synovial sarcoma, three extraskeletal myxoid chondrosarcomas, two high-grade myxofibrosarcoma (one conventional, one epithelioid), two undifferentiated pleomorphic sarcoma (one with giant cells) and one each myxoinflammatory fibroblastic sarcoma, conventional hyaline chondrosarcoma, and high-grade myofibroblastic sarcoma. All tumours were treated by segmental resection or amputation. Adjuvant therapy was given in selected cases. Follow-up ranged from 11 to 150 months. Of patients with follow-up, two died of disease; one developed pulmonary metastases after 6 years and was then lost to follow-up. Nine patients were alive and free of disease 12-150 months after diagnosis.

CONCLUSIONS

Primary sarcomas of the joints are very rare and most frequently affect the knee. Our experience indicates that synovial sarcoma and extraskeletal myxoid chondrosarcoma are the most common intra-articular sarcomas.

Synovial chondromatosis and chondrosarcoma: a diagnostic dilemma

Purpose: The progression of synovial chondromatosis to chondrosarcoma is very rare. Distinction between these two entities may be difficult on histology alone, and should be based on clinical, radiographic and microscopic evidence. Immunohistochemical markers that would facilitate differentiation between synovial chondromatosis and chondrosarcoma are currently being investigated.

Patients: We describe the cases of two patients who presented with synovial chondromatosis and progression to synovial chondrosarcoma during periods of 7 and 11 years. Several biopsies and resected specimens demonstrated synovial chondromatosis before a diagnosis of chondrosarcoma was made.

Method: We have examined five markers (Bcl2, Ki67, p27, p16, and p53) in all specimens from these cases, as well as known cases of chondromatosis and chondrosarcoma for control purposes.

Results: We found increased expression of Bcl2 in benign chondromatosis compared to synovial or central chondrosarcomas.

Discussion: Distinction between chondromatosis and its progression to low grade chondrosarcoma is difficult at histological level, and must involve incorporation of clinical and radiographical data. Although preliminary, our study suggests that reduced or absent expression of Bcl2 is associated withmalignant transformation of chondromatosis.

Tumors and diseases of the joint

A variety of different diseases affect the synovium, including infection, noninfectious immunologic inflammatory conditions, degenerative arthroses, crystal deposits, trauma, and tumors. Tumors of the synovium are relatively uncommon. Any mesenchymal tumor may arise in the synovium, but most recapitulate its normal counterpart including synoviocytes, blood vessels, fat, and fibrous tissue. These tumors can arise in any synovial lined structures both within joints and in extraarticular locations. Most synovial tumors are benign. Malignant tumors are rare but important to recognize because many are aggressive and must be treated appropriately. Among common nonneoplastic conditions that affect the synovium and surrounding structures are crystal deposits such as monosodium urate crystals, calcium pyrophosphate dihydrate crystals, and hydroxyapatite crystals. These crystal deposits may be asymptomatic or cause severe pain or chronic joint destruction. Their accurate identification is important to guide appropriate therapy.

Primary tumours of the synovium. A report of four cases of malignant tumour

Four patients who developed malignant synovial tumours are described; one with chondromatosis developed a synovial chondrosarcoma and three with pigmented villonodular synovitis developed malignant change. The relevant literature is discussed.

Imaging of Synovial Chondromatosis with Radiologic-Pathologic Correlation

Primary synovial chondromatosis represents an uncommon benign neoplastic process with hyaline cartilage nodules in the subsynovial tissue of a joint, tendon sheath, or bursa. The nodules may enlarge and detach from the synovium. The knee, followed by the hip, in male adults are the most commonly involved sites and patient population. The pathologic appearance may simulate chondrosarcoma because of significant histologic atypia, and radiologic correlation to localize the process as synovially based is vital for correct diagnosis. Radiologic findings are frequently pathognomonic. Radiographs reveal multiple intraarticular calcifications (70%-95% of cases) of similar size and shape, distributed throughout the joint, with typical "ring-and-arc" chondroid mineralization. Extrinsic erosion of bone is seen in 20%-50% of cases. Computed tomography (CT) optimally depicts the calcified intraarticular fragments and extrinsic bone erosion. Magnetic resonance (MR) imaging findings are more variable, depending on the degree of mineralization, although the most common pattern (77% of cases) reveals low to intermediate signal intensity with T1-weighting and very high signal intensity with T2-weighting with hypointense calcifications. These signal intensity characteristics on MR images and low attenuation of the nonmineralized regions on CT scans reflect the high water content of the cartilaginous lesions. CT and MR imaging depict the extent of the synovial disease (particularly surrounding soft-tissue involvement) and lobular growth. Secondary synovial chondromatosis can be distinguished from primary disease both radiologically (underlying articular disease and fewer chondral bodies of variable size and shape) and pathologically (concentric rings of growth). Treatment of primary disease is surgical synovectomy with removal of chondral fragments; recurrence rates range from 3% to 23%. Malignant transformation to chondrosarcoma is unusual (5% of cases) and, although difficult to distinguish from benign disease, is suggested by multiple recurrences and marrow invasion. Recognizing the appearances of primary synovial chondromatosis, which reflect their underlying pathologic characteristics, improves radiologic assessment and is important to optimize patient management.

Vertebral synovial chondromatosis. Report of two cases and review of the literature

Synovial chondromatosis is an uncommon disorder characterized by the formation of multiple cartilaginous nodules within the synovium, most commonly affecting large joints. Its involvement with the spine is rare; only six cases have been reported. The authors describe two patients with synovial chondromatosis involving the cervical spine. In the first case, synovial chondromatosis arose from the left C1-2 facet joint. This patient underwent a two-stage procedure including a posterior approach for tumor resection and occipitocervical fusion as well as a transmandibular circumglossal approach to the anterior craniocervical junction to complete the tumor removal. Interestingly, on histopathological examination, scattered foci of low-grade chondrosarcoma were intermixed within the synovial chondromatosis. To the authors' knowledge, this is the first report of secondary low-grade chondrosarcoma arising in vertebral synovial chondromatosis. In the second case, synovial chondromatosis involved the left C4-5 facet joint. Tumor resection and cervical fusion were performed via a posterior approach. In this report, the authors describe the clinical presentation, radiographic findings, operative details, histopathological features, and clinicoradiological follow-up data obtained in these two patients and review the literature pertaining to this rare entity.

Primary synovial chondromatosis: a clinicopathologic review and assessment of malignant potential

This is a clinicopathologic review of 53 cases of primary synovial chondromatosis covering a period of 30 years. The average age at presentation was 41 years (range, 17 to 64 years) with a male/female preponderance of 1.8:1. The condition was always monarticular, the most common site being the knee joint (70%) followed by the hip (20%). Degenerative joint disease was well established in three patients (5%), all occurring in the hip. Nine patients suffered recurrences (15%), including three that became malignant. There was no relationship between the age and site of the lesion, nor between the degree of cellularity of the cartilage and age or site. However, there was an association between cellularity of the cartilage and the extent of calcification and ossification--highly cellular lesions were poorly calcified and ossified, but heavily calcified lesions were usually of relatively low cellularity. There was no relationship between extent of calcification and ossification and the age of the patient. Three patients suffered malignant change representing a relative risk of 5%, much higher than that quoted in other series. This suggests that primary synovial chondromatosis has a significant potential for malignant change.

Chondrosarcomas of the synovium

Chondrosarcoma of the synovium, either primary or secondary to synovial chondromatosis, is rare. Ten cases of synovial chondrosarcoma were studied (four from the Mayo Clinic files and six from the authors' consultation files). Two were considered primary. In five cases there was evidence of preexisting synovial chondromatosis, and in the remaining three, there was a suggestion of preexisting disease. Several histologic features were found that were helpful to diagnose malignancy. The most important ones were loss of the "clustering" growth pattern typical of synovial chondromatosis, myxoid change in the matrix, areas of necrosis, and spindling at the periphery of chondroid lobules. Pulmonary metastasis developed in five of nine patients; three of these patients died.