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Title : A 39 year-old female with low back pain and febrile sense
Date : July 16, 2010
Contributed by

Seung ji Kang,MD  
Samsung Medical Center, Seoul, Korea

Patient History
Age/Sex A 39 year-old female
Chief complaint low back pain and febrile sense
Present illness

Women aged 39 was referred with a month history of back pain and fever. She had got acupuncture on her back muscles when she felt pain first time, a month ago. But the pain had been getting worse and a limb had been evident.

Past medical history

Past medical history

Physical examination

BP-HR -RR -BT 104/67mmHg-88/min-20/min-38.1℃

Epiastric tenderness and psoas sign was evident.

Initial laboratory findings

CBC 16480(segment neutrophil 82.8%)–10.7-306K, hsCRP 20.51mg/dL

Radiologic findings

Question - ID Case of the Week ( July 16, 2010 )
What do you think the most likely diagnosis is?
Correct Answer

Actinomycosis presenting as psoas abscess


Actinomycesis a gram-positive, anaerobic, filamentous bacterium commensal in the oral cavity, intestinal tract and vagina. When the Actinomyces causes abdominal infection, it is usually preceded by conditions that result in loss of mucosal integrity, such as gastrointestinal surgery, diverticulitis, appendicitis, or foreign bodies. Actinomycosis is diagnosed preoperatively in fewer than 10% of cases. Typically the pathologist detects colonies of Actinomyces within abscess in resected tissue. Theses correspond to ‘sulphur granules’ that may be identified by the naked eye in pus. When actinomycotic abdominal masses and strictures are identified without surgery, long term penicillin can avoid operation. A computed tomographic scan will usually show a contrast enhancing multicystic lesion and the diagnosis can be confirmed by needle aspiration.

 There are very few reports of abdominal actinomycosis presenting as psoas abscess and to our knowledge with all components of the classic triad-pain, fever and a limp is very rare. Needle aspiration of our patient’s psoas abscess might have provided the diagnosis. First-line investigation of a psoas abscess should include needle aspiration, which may be both diagnostic and therapeutic.


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