๐ ็ธฝ็ฎ้ ๏ฝ ๐ ่ฑๆๅๆ๏ผๆฌ็ฏ๏ผ ๏ฝ ๐ ๅฎๆด็ฟป่ญฏ ๏ฝ โญ ็ฒพ่ฏ็ญ่จ
Synovial metaplasia
Synovial metaplasia
Clinical features
Synovial metaplasia is a rare phenomenon that has no distinctive clinical features. It usually presents as an incidental histologic finding in biopsies performed at sites of previous trauma, particularly surgery.1โ5 Synovial metaplasia is not uncommon in the setting of silicone implants.3 It may also be seen in association with the use of tissue expansors. Synovial metaplasia-like changes have also been described in oral mucoceles under the rubric papillary synovial metaplasia-like changes or myxoglobulinosis.6โ9 A single recurrent lesion has been described and a case was documented in a patient with Ehlers-Danlos syndrome.10,11
Pathogenesis and histologic features It has been suggested that, at least in cases associated with foreign material, the phenomenon probably represents a specialized form of tissue repair.12
Histology shows a cystic cavity with a lining identical to that seen in hyperplastic synovial tissue and composed of histiocyte-like cells which are variably positive for CD68 (Figs 35.642 and 35.643).
Fig. 35.642 Synovial metaplasia: low-power view of cyst lined by cells with intensely eosinophilic cytoplasm.
Fig. 35.643 Synovial metaplasia: high-power view.