Department of Orthopaedic Surgery, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, Guangdong Province, People's Republic of China.
Department of Orthopaedic Surgery, The second affiliated hospital of ChongQing Medical University, Chongqing, China.
Int Orthop. 2019 Jul;43(7):1727-1734. doi: 10.1007/s00264-018-4083-8. Epub 2018 Aug 8.
Synovial cyst of knee cruciate ligament (SCKCL) is a rare condition but can cause severe knee pain. The understanding of its etiology is relatively poor. This current study aimed to elucidate the pathogenesis of SCKCL based on a series of histo- and cytopathological examination.
Ten SCKCL patients who underwent arthroscopy were enrolled, among five patients claimed past knee injury. Hematoxylin & eosin staining was conducted to the cyst wall tissue sections and Papanicolaou staining to the cyst fluid smear. Prussian blue staining was employed to both the wall section and fluid smear. Immumohistochemical staining for mesothelial cells (MC), epithelial cells (CK), vascular endothelial cells (CD31), monocytes (CD68), and hematogenous stem cells (CD117) were taken to elucidate the possible involvement of various cell types in the development of SCKCL.
No erythrocyte was discovered in the fluid; however, Prussian blue stained hemosiderin particles were found in the cyst wall and fluid, suggesting past hemorrhage in all patients. Abundant lymphocytes and plasmocytes were observed in the cyst wall and fluid. In addition, the cyst lining was infiltrated with abundant CD68(+) monocytes while only few MC(+) mesothelial cells were sporadically observed in four samples. The cyst submucosa was also diffused with abundant CD68(+) monocytes and proliferated capillaries stained with CD31. CD117-positve hematogenous stem cells were sporadically observed in eight specimens.
Our findings provided evidence that SCKCL is not a mature synovial cyst but rather an inflammatory pseudo-cyst. It may have resulted from past minor hemorrhage and intra-ligament chronic inflammation.
膝关节十字韧带滑膜囊肿（SCKCL）是一种罕见的疾病，但可引起严重的膝关节疼痛。其发病机制的理解相对较差。本研究旨在通过一系列组织病理学和细胞学检查来阐明 SCKCL 的发病机制。
共纳入 10 例接受关节镜检查的 SCKCL 患者，其中 5 例患者自述有膝关节外伤史。对囊肿壁组织切片进行苏木精-伊红染色，对囊液涂片进行巴氏染色。对壁切片和囊液涂片进行普鲁士蓝染色。对间皮细胞（MC）、上皮细胞（CK）、血管内皮细胞（CD31）、单核细胞（CD68）和血源性干细胞（CD117）进行免疫组织化学染色，以阐明各种细胞类型在 SCKCL 发展中的可能作用。
囊液中未发现红细胞，但在囊肿壁和囊液中发现普鲁士蓝染色的含铁血黄素颗粒，提示所有患者均有既往出血。囊肿壁和囊液中可见大量淋巴细胞和浆细胞。此外，囊肿内衬有大量 CD68（+）单核细胞浸润，而在四个样本中仅偶尔观察到少量 MC（+）间皮细胞。囊肿黏膜下层也弥漫着大量 CD68（+）单核细胞和增生的 CD31 染色的毛细血管。在 8 个标本中，CD117 阳性的血源性干细胞呈散在分布。
我们的研究结果表明，SCKCL 不是成熟的滑膜囊肿，而是一种炎症性假性囊肿。它可能是由既往轻微出血和韧带内慢性炎症引起的。
