化膿性關節炎以膕囊腫破裂導致假性血栓性靜脈炎作為初期臨床表現

Ruptured Popliteal Cyst Leading to Pseudothrombophlebitis in a Patient with Pyogenic Arthritis

化膿性關節炎初期以膕囊腫破裂引起腓腸肌肉腫痛，其臨床表現與深部血栓性靜脈炎難以區別。本文報告一位50歲女性病人，因三天前突然右下肢腫痛，發燒而住院。理學檢查發現右膝及右下肢紅腫熱痛，無法走路，且右下肢Homans氏表徵呈陽性。實驗室檢驗發現白血球過多，從血液及關節液培養出鏈球菌。使用Gadolinium顯影劑後之核磁共振造影發現右膝之膕囊腫腫大，並破裂至腓腸肌。在初期診斷為血栓性靜脈炎，並使用Heparin 5000單位皮下立刻注射，再以每小時1000單位連續靜脈注射治療共三天後，症狀並無改善。最後經確定為化膿性關節炎合併膕囊腫破裂後，並改用Aqueous penicillin每6小時靜脈注射三百萬單位治療共二週，並續以每天1000mg Cephalexin口服治療共二週後，右下肢功能恢復。本文提出經顯影劑加強後之核磁共振造影能提供早期顯示出化膿性關節炎併發膕囊腫破裂。在腓腸肌腫痛同時合併有膝關節滲液時，必須考慮膕囊腫破裂。

Pyogenic arthritis presenting as a ruptured popliteal cyst results in a painful swollen calf which may be confused with thrombophlebitis. We describe a case of a 50-year-old female patient who presented with the sudden onset of pain and swelling of her right knee and calf and fever of three days' duration. On examination, the right knee and leg were swollen, hot and tender and she was unable to walk. Homans' sign of the right leg was positive. Laboratory findings included leukocytosis with a shift to the left. Streptococci were isolated from blood and synovial fluid. Gadopentetate dimeglumine (Gd-DTPA)- enhanced magnetic resonance imaging (MRI) of right leg demonstrated a distended popliteal cyst which had ruptured into the gastrocnemius muscle. The patient failed to respond to heparin therapy for three days under the tentative diagnosis of thrombophlebitis. She was treated with aqueous penicllin 300 million units intravenously every 6 hour for 2 weeks followed by cephalexin 1000 mg/day orally for 2 weeks when the final diagnosis of pyogenic arthritis presenting as ruptured popliteal cyst was established. The swelling of the right knee and calf gradually subsided and she regained full function of the right leg. Dissecting popliteal cyst should be considered in conditions with calf swelling and intra-articular effusion of the knee. We also suggest contrast- enhanced MRI as an early diagnostic tool in cases of pyogenic arthritis complicated with a ruptured pyogenic popliteal cyst which may mimic thrombophlebitis.