Schistosomal appendicitis: incidence in Japan and a case report.

Schistosomal appendicitis is very rare in developed countries like the USA, Europe, and Japan. The author reviewed 311 pathologic archival specimens of vermiform appendix over the past 10 years. One case of schistosomal appendicitis was recognized. Therefore, the incidence of this disease was 0.32% in all appendices surgically resected in our hospital. The patient was a 41-year-old woman presenting with lower abdominal pain. She was a sailor traveling to many countries including endemic areas. Physical examination, laboratory data, and imaging modalities suggested an acute appendicitis, and appendectomy was performed under the diagnosis of ordinary appendicitis. Histologically, numerous schistosomal eggs were present in the vasculatures throughout the appendiceal walls. Some of the eggs were calcified. Stromal foreign body reaction was also recognized. The appendicitis was phlegmonous consisting of severe infiltrations of neutrophils and eosinophils. Acute serositis was also noted. Examination of feces revealed numerous eggs of Schistosoma mansoni. Clinicians should be aware of schistosomal appendicitis.