一名30歲女性病人，生產三胎，並有使用八年避孕器的歷史。因腹部腫塊，下腹部痛已兩個月故而入院。身體檢查方面，在下腹部有一個5×6公分，固定無壓痛性的腫塊，在檢驗報告中無特殊。在攝影檢查包括婦科超音波、下腹部電腦斷層攝影、膀胱鏡、乙狀結腸鏡、大小腸攝影等皆已完成，但卻無明確之開刀前診斷。剖腹探查手術顯示一處膿瘍空洞於腹直肌上，並大網膜嚴重粘連至大腸、迴腸、及膀胱。病理切片報告看出放線菌合併急慢性發炎，開刀後使用水溶性青黴素治療14天及口服四環黴素六個月，並且在門診追蹤已無復發。人類放線菌是以一種慢性化膿的發炎表現出多發性膿瘍、竇、肉芽及纖維性組織等組成。放線菌症及子宮內避孕器的存在，介於骨盆及腹部腫瘤鑑別時應想到它的可能性，正確的診斷及早期治療是為了降低罹病率及防止潛在致命之影響。

Actinomycosis is an unusual intra-abdominal infection, often mistaken for other conditions, and is difficult to diagnose non-operatively. A rare case of actinomycosis mimicking abdominal tumor with bladder infiltration was presented. Laparotomy, drainage of the abscess cavity and biopsy of the lesion were performed under the impression of abdominal tumor with small bowel and bladder involvement. Post-operative parenteral penicillin for fourteen days and oral tetracycline for six months were used with a good result.