Background: A rare cause of nonspecific, chronic abdominal pain is actinomycosis. Extensive disease can cause chronic peritonitis mimicking malignancy.
Case description: A 59-year-old women presented with aspecific chronic abdominal pain, after 23 years of IUD use. Imaging showed two solid masses in the abdomen suggestive of malignant disease. Additional diagnostic procedures did not prove malignancy and biopsies showed chronic inflammation. In the absence of proof of malignancy and with regard to the long-term IUD use, actinomycosis was considered. A Pap smear showed Actinomyces 5 years earlier. Antibiotic treatment was instituted and remission of the intra-abdominal masses was seen after six months of treatment.
Conclusion: Consider actinomycosis in a patient presenting with abdominal pain and (long-term) IUD use. Diagnosis is challenging and frequently impossible to confirm before treatment. This diagnosis should be considered after thorough workup for other diseases, especially malignancy. After such analysis, starting antibiotic therapy could prevent secondary complications and invasive procedures.