Case Study: Intra-abdominal actinomycosis may present as a malignant tumor


Actinomycosis is a chronic suppurative granulomatous inflammatory disease caused by different Actinomyces species, mainly Actinomyces israelii. It is an anaerobic gram-positive bacteria. The intra-abdominal location of this infection is rare. Here I shall discuss the case of a 45-year-old female with intra-abdominal actinomycosis that was clinically suspected as a case of malignant tumor. The diagnosis was made with aspiration cytology, and the patient was treated conservatively.


Abdominopelvic actinomycosis can be suspected clinically as well as radiologically, and there are few case reports on the same, but in all instances, the diagnosis was confirmed histologically only after surgical intervention. Abdominopelvic actinomycosis may result from intra-uterine contraceptive devices or may occur as a post-surgical complication. In rare cases, it may occur spontaneously. Clinically, it has wide range of presentation – tumor, asymptomatic mass, or acute abdomen.
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Case Presentation

A 45-year-old normotensive, nondiabetic female presented with chronic ill-health six weeks after a total abdominal hysterectomy with bilateral salpingo-oophorectomy for multiple symptomatic uterine leiomyomas. The scar was healthy, and no collection or tenderness was present. She had anorexia, indigestion, chronic low-grade fever and occasional loose motions. The patient never used any contraceptives, including intra-uterine devices.

InvestigationsActinomycosis, MGG 100X

  1. X-ray abdomen
  2. Routine blood tests: neutrophilic leucocytosis
  3. Monteux test for tuberculosis: negative
  4. HIV serology: negative
  5. Ultrasound revealed a heterogeneous mass with adherent bowel loops in the peritoneal cavity.
  6. FNAC: confirmed the diagnosis

Differential Diagnosis Actinomycosis, MGG 400X

  1. Intra-abdominal malignancy (SARCOMA, CARCINOMA)
  2. Mesenteric fibromatosis
  3. Foreign bodies left over during previous operation
  4. Diverticular abscess
  5. Inflammatory bowel disease


Penicillin G parenterally, 10 to 20 million units per day for 4 to 6 weeks, followed by oral therapy of 25 to 30 mg per kg every six hours, for an additional 6 to 12 months.

Outcome and Follow-Up

She was treated conservatively and responded within three days. No surgery was necessary. One year after the treatment above, the patient is doing well.


In the abdominal form of actinomycosis, the most commonly affected organs are the appendix and caecum, but other reported sites include the colon, stomach, liver, gallbladder, pancreas, small bowel, anorectal region, pelvis, abdominal wall and urinary tract [1]. The pathogenesis of abdominal actinomycosis has not been well understood yet, although medical history usually reveals appendectomy, intra-abdominal organ perforation, previous surgery or IUD use [2].

In the present case, microscopic examination revealed huge load of fluffy dark-blue colonies of thin filamentous gram-positive bacteria with a cotton wool-like appearance at places. Modified AFB stain highlighted the positive pink filaments. The background contained numerous macrophages, multinucleated giant cells, lymphocytes and plasma cells. The possibility of tuberculosis or malignancy was ruled out. A diagnosis of actinomycosis was given immediately, to prevent any more surgical intervention.

In most cases, complete excision of the affected tissues is impossible [2, 3]. Penicillin dramatically changed the outcomes of patients with actinomycosis. The cure rate increased from 5 to 90 percent with the use of penicillin. In addition, recurrences after penicillin therapy have not been reported in long-term follow-ups. Surgical procedures are challenging because of extensive intra-abdominal adhesions and the loss of anatomical planes. The role of the surgeon is limited to excision of necrotic tissue, drainage of purulent material, removal of persistent fistulas, and retrieval of tissue for biopsy [2-4]. The present case also responded well to penicillin-based conservative therapy.

Learning Points/Take Home Messages

Intra-abdominal actinomycosis may occur in immunocompetent patients as a post-operative complication, and may mimic a malignant tumor.

About The Author

Dr. Samanta, MBBS, MD is currently a consultant at Suraksha diagnostic PVT. LTD. Kolkata, India for histopath, cytopath and hematology. His other interests are: oncopathology, bone marrow and neuropathology.


References (click to show/hide)

  1. Berardi R. S. Abdominal actinomycosis. Surg Gynecol Obstet, 1979. 149: 257-66.
  2. Yeguez J. F., Martinez S. A., Sandsl. R., Hellingerm. D. Pelvic actinomycosis presenting as malignant large bowel obstruction : a case report and a review of the literature. Am Surg, 2000. 66: 85 – 90.
  3. Kaya E., Yilmazlar T., Emiroglu Z. et al. Colonic actinomycosis: report of a case and review of the literature. Surg Today, 1995. 25: 923 – 26.
  4. Sumer Y., Yilmaz B., Emre B., Ugur C. Abdominal mass secondary to Actinomyces infection : an unusual presentation and its treatment. J Postgrad Med, 2004, 50: 115 – 17.


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One Comment

  1. Kamla Sharma
    Posted Oct 2013 at 1:38 pm | Permalink

    Interesting case. Dr Samanta.

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