[Abdominal actinomycosis and retroperitoneal fibrosis. Considerations on a clinical case]

Abdominal actinomycosis is a rare disease which often resembles an acute suppurative infection or/and abdominal tumour causing abscesses, fistulas and massive fibrosis. The preoperative diagnosis is difficult and surgical exploration is always needed because of major involvement of visceral and retroperitoneal structures. The disease can be diagnosed with certainty only on the basis of findings of bacterial colonies in histopathologic sections and typical sulphur grains in secretions from fistulas. The authors describe a case of abdominal actinomycosis involving the caecum and right colon, causing extensive retroperitoneal fibrosis and a fistula tract with an external cutaneous orifice at the level of the right iliac crest. These features resembled an acute appendicitis at first, and several surgical explorations were required before a correct diagnosis could be achieved. Abdominal actinomycosis can be treated by simple administration of antibiotics. With a correct diagnosis, medical therapy alone has proved effective in a substantial percentage of patients, thus avoiding the need for surgery, if important visceral or retroperitoneal structures are not involved. Abdominal actinomycosis always requires a careful differential diagnosis and must be considered in patients presenting abdominal tumours associated with abscesses and/or fistulas since early and efficient medical therapy, along with surgical intervention, where necessary, can lead to definitive recovery. Useful diagnostic tools are abdominal CT and selective FNAB.