Splenic actinomycosis presenting as subcutaneous abscesses

ARTICLE

Auteur(s) : Yuichiro Endo¹, Miki Tanioka^1,2, Reiko Taki¹, Satoshi Kore-Eda¹, Atsushi Utani¹, Yoshiki Miyachi¹

¹Department of Dermatology, Kyoto University, 54 Shogoin Kawahara-cho, Sakyo-ku, Kyoto, 606-8507, Japan
²Fukui Red Cross Hospital

Actinomyces are gram-positive, non-acid fast anaerobic bacteria that are normal inhabitants of the oral cavity and intestinal tract, but acquire pathogenicity through invasion of breached or necrotic tissue [1-6]. The most common pathogen is Actinomyces israelii. Here, we report a unique case of actinomyocosis presenting with splenic and subsequent muscular abscesses in an immunocompetent patient.

A 49-year-old man walked into our hospital with a three-month history of subcutaneous induration on the left side of the abdomen. He had begun to feel discomfort in the lateral abdomen three months previously. Two months before the first visit, subcutaneous induration and tenderness became obvious. He had experienced fever, appetite loss and a decrease in urine quantity in the last two days. His medical history was free of predisposing risk factors, such as autoimmune disease, alcoholism, HIV infection, hepatitis, or intravenous drug addiction.

Physical examination found abdominal guarding and subcutaneous induration without significant epidermal changes (figure 1A). His body temperature, blood pressure and pulse rate were 39.0 °C, 112/70 mm Hg and 112 beats per minute, respectively. Significant laboratory findings were as follows: white blood cell 22,200/mm³ (Neutrophil 93.0%), C-reactive protein 35.8 mg/dL, serum creatinine 2.7 mg/dL, and BUN 61 mg/dL. A CT scan revealed a splenic abscess of 62 × 45 mm in size which seemed to invade the back and abdominal muscles, forming another abscess of 90 × 75 mm in size (figure 1B). Both lesions consisted of low absorption areas surrounded by high absorption areas.

Although surgical debridement of an abscess in the skin and muscle was performed, splenectomy was not carried out because the patient went into septic shock during the operation. He received standard sepsis management and sulbactam/ampicillin compound 9 g/day and clindamycin 1.8 g/day. Two weeks later, sulbactam/ampicillin was changed to ceftriaxone 2 g/day because of a drug-induced eruption due to ampicillin. Histopathological study of the debridement specimen confirmed sulphur granules (figures 1C and D). Actinomyces israelii, and other normal inhabitants of the oral cavity were detected from repeated bacterial cultures. One month later, systemic antibiotics were switched to oral clindamycin as a follow-up CT confirmed that the splenic abscess was resolved. Clindamycin was planned to continue for one year.

Actinomycosis is a rare, chronic granulomatous disease. The cervicofacial area is most frequently involved in approximately half of cases, the lung is involved in 15% and the abdomen in 20%, respectively [1, 4]. Abdominal actinomycosis presents as a consequence of spreading from gastrointestinal tract inflammation, for instance, appendicitis and diverticulitis, while splenic abscesses are less common [1, 2]. Although bacteremia, local trauma to the spleen and diabetes mellitus are suggested as possible triggers of splenic actinomycosis [2, 5], none was present in the present case.

Diagnosis of actinomycosis by CT scanning is usually difficult because it is described as an infiltrative mass irrelevant of tissue planes, which resembles the findings of solid tumours or tuberculosis [1-3]. Therefore, skin biopsy and cultural identification are required for definite diagnosis. In our case, a biopsy and cultures from an abscess were easily performed, which enabled a prompt diagnosis of actinomycosis. In addition, very small air lesions in the masses led us to consider possibility of anaerobic bacterial infection.

Treatments include surgical resection and antibiotics. Splenectomy is the gold standard of treatment of actinomycotic spleen abscess, to avoid rupture [2]. The first line of antibiotics is penicillin although ceftriaxone and clindamycin are useful alternatives in case of allergy to penicillin [1-3, 5, 6]. Duration of the treatment should be at least 6 months. Our patient resulted in a favourable outcome without splenectomy, probably because he was fortunately free of serious complications.

Acknowledgements

References

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