Patellar Subluxation With Early-Phase Synovial Chondromatosis of the Knee

Extra-articular synovial osteochondroma of the Hoffa's fat pad involving the patellar tendon: A case report and literature review

Synovial osteochondroma (SO) is a relatively uncommon tumor affecting the synovial joints that is characterized by the development of hyaline cartilage from the synovial membrane. The basic pathophysiology of SO is thought to be the metaplastic change of the synovium to hyaline cartilage. Large extra- or para-articular lesions in the Hoffa's fat pad are relatively uncommon. A 56-year-old woman complained of knee pain associated with a large lesion on the anterior of the right knee. She also had restricted range of motion in the knee. Examination revealed an elastic hard 8x9-cm lesion involving the patellar tendon. Computed tomography and magnetic resonance imaging demonstrated a mosaic-intensity mass lesion in the inferior side of the Hoffa's fat pad as well as the patellar tendon. The patient underwent needle biopsy. Histological analysis revealed a solitary SO. There were no atypical features suggestive of malignancy and the mass was resected marginally. The patient had no recurrence or knee functional disorder 3 years postoperatively. There are no reports of SO involving the patellar tendon with restriction of range of motion. Removal of the mass lesion for management for SO, as in the present case, is unusual. To the best of our knowledge, this is the first case of extra-articular SO in the Hoffa's fat pad involving the patellar tendon causing a restriction of range of motion of the knee. Marginal surgical resection improved knee function.

Synovial chondroma in Hoffa's fat pad: Case report and literature review of a rare disorder

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Synovial chrondroma is a rare condition of which the aetiology remains unclear. Large palpable lesions represent an atypical presentation.

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The diagnosis is often not immediately apparent. However it is usually suggested by radiologic investigation and confirmed on histology.

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Disease recurrence is not infrequent after excision (15–23%) and patients should be counselled regarding this.

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Malignant transformation whilst uncommon has been described. At present no definite criteria exist in order to make the diagnosis of malignancy.

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Due to the above risks of recurrence and malignancy, long term follow up of affected patients is advised.

Introduction

Synovial chrondomatosis is a rare disorder characterised by the development of hyaline cartilage from the synovial membrane. Large isolated lesions in the Hoffa's fat pad are an uncommon entity.

Presentation of case

A 33 year old gentleman presented complaining of progressive knee pain associated with an enlarging lesion on the anterior aspect of the right knee, with associated locking and giving way. Examination revealed a firm 4 × 5 cm lesion adjacent to the patellar tendon.

Subsequent CT and MRI demonstrated a lesion in the inferior aspect of Hoffa’s fat pad, with a second lesion adjacent to the proximal tibiofibular joint, in addition to advanced degenerative changes and a meniscal tear.

He proceeded to excisional biopsy. Histological analysis was consistent with a solitary synovial osteochondroma. There were no atypical features suggestive of malignancy.

Discussion

Synovial chondromatosis is a rare disorder affecting the synovial joints. The underlying pathophysiology is thought to be metaplastic change of the synovium to hyaline cartilaginous tissue. Transformation to malignancy has been described but is uncommon with an estimated risk of 5%. It is 1.5–2 times as prevalent in males versus females. Symptoms which patients may complain of include pain;locking and giving way; and palpable masses.

The management usually entails removal of the mass lesion with or without accompanying synovectomy. Recurrence of disease may occur in up to 15–23% of patients.

Conclusion

Synovial chrondromatosis is a rare but well recognised condition. Long term follow up is advised in view of the risk of recurrence and malignant transformation.

[Interest of imaging in tumors benign bone in children]

Benign bone tumors are more common than malignant tumors in pediatrics. The exostosis (ostéchondrome) is the most common. The different imaging techniques are pivotal in the study of tumors including its standard radiography. The aim of this work is to highlight the interest in imaging the diagnostic management of bone benign tumors in children through a retrospective study of 169 patients. All patients were investigated by plain radiography, scanner supplement with multiplanar reconstruction before and after injection of PDC and / or MRI 1. 5 Tesla was performed according to the indication. The average age is 6 years with a slight male predominance. Clinically, the swelling is present in 35% of cases. The pain in 29% of cases. The most common location is the metaphyseal long bone on: Femur: 25% of cases, humerus: 17% of cases, Tibia: 21% of cases. Main Benign tumors are found exostosis (20. 12%), bone cyst (31. 95%) and osteoblastoma (16, 57%). The imagery is used to specify the topography and extension of the lesion in the bone provide arguments in favor of benign and sometimes in favor of the cause of the injury. The only standard radiograph often provides a diagnosis of certainty in some cases.