Short CommunicationIntra-articular synovial lipoma of the knee joint (located in the lateral recess): A case report and review of the literature
Introduction
Lipomas are one of the most common of all benign neoplasms of soft tissues, and although they may arise almost anywhere in the body [1], intra-articular synovial lipomas are rarely seen. As far as we know there have been only twelve case reports of intra-articular synovial lipoma in English language journals [2], [3], [4], [5], [6], [7], [8], [9], [10], [11], [12], [13]. Intra-articular synovial lipomas should be differentiated from other similar lipomatoid conditions such as villous lipomatous proliferation of the synovial membrane (lipoma arborescens) [14], [15], [16], [17], [18], [19], [20], [21], [22], [23], [24], [25], [26] or Hoffa disease [27], [28], [29], [30], [31]. Intra-articular synovial lipomas mainly develop in the knee joint [2], [3], [4], [5], [6], [7], [8], [9], [10], [11]. They typically arise from fat pad area [6], [8], [10], or from the suprapatellar pouch [3], [4], [5], [7]. One from the medial meniscus [2] and two located in the femoral intercondylar notch [9], [11] were also reported. However, there has been one reported case of an intra-articular synovial lipoma in the hip [12] and one in a facet joint of the lumbar spine [13]. This article reports on a case of a catching knee caused by an intra-articular synovial lipoma with a stalk located in the lateral recess of the knee joint arising from the suprapatellar pouch. As far as we know, no intra-articular synovial lipoma located in the lateral recess has been reported, and two similar cases of locked knee caused by the impingement of the lipoma within the patellofemoral joint have been reported. And this article also describes how it can be distinguished from other lipomatoid conditions such as villous lipomatous proliferation of the synovial membrane (lipoma arborescens) or Hoffa disease. We also emphasize the importance of considering an intra-articular synovial lipoma in the differential diagnoses when examining a patient with a catching or locking knee. The patient was informed that data concerning the case would be submitted for publication.
Section snippets
Case report
A 66-year-old female presented with a mass involving the left knee joint. The patient suffered from sudden knee pain and a catching or slight interruption of normal motion of the left knee three times in the previous three months. The sudden knee pain and catching of the left knee was relieved by flexing and extending her knee. The patient had never noticed the mass before the symptoms appeared. The patient's local orthopaedist referred the patient to our hospital in July 2005. There was no
Discussion
Lipomas, one of the most common of all benign neoplasms of soft tissues, are composed of mature adipocytes and [1] can arise as solitary masses in any part of the human body where there is fatty tissue [3], [32]. They are subclassified according to the site of origin as 1) subcutaneous (most frequent site), 2) intermuscular and intramuscular, 3) intrathoracic, 4) intraperitoneal and retroperitoneal, 5) intraoral, 6) arising in various organs, 7) arising in the central or peripheral nervous
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