RESUMO
BACKGROUND: Abdominal actinomycosis is a rare infection with a difficult diagnosis that can simulate multiple surgical scenarios such as neoplasms or complications of inflammatory bowel disease. CLINICAL CASE: We present the case of a 69-year-old female who underwent emergency surgery due to a difficult and painful tumor, suggesting an incarcerated umbilical hernia. Whitish lesions were discovered in the abdominal wall and a stenotic colonic mass was managed similar to a neoplasm. Anatomopathological study showed abdominal actinomycosis, requiring a lengthy course with penicillin. CONCLUSION: Actinomycosis infection is a chronic disease with granulomatous lesions and areas of fibrosis. Its incidence is increasing and the location usually is cervicofacial. The great challenge of this pathology lies in the diagnosis because it simulates different diseases of diverse natures. This type of infection can be treated successfully with drugs if the etiology is identified in a timely manner. However, in the case of our patient, the manner of presentation made diagnosis more difficult prior to surgical trauma.