An unusual case of invasive Blastocystis hominis infection

Abstract

A 47-year-old African-American man presented with 3-week history of rectal bleeding. It had started 6 weeks previously while he was visiting Nigeria, with watery diarrhea, abdominal bloating, and pain. His symptoms had resolved without treatment within 2 weeks. Physical examination and hematological and biochemical profiles were all normal. Colonoscopy showed several large ulcers in the cecum, hepatic flexure, and transverse colon with normal surrounding mucosa ( " Fig. Pathologic examination of biopsies showed exudates with necrosis, and pieces of colonic mucosa with severe acute and chronic inflammation, and focal acute cryptitis, plus multiple vacuolated and amoeboid structures ( " Fig. Subsequent stool study with a special trichrome stain confirmed the diagnosis of Blastocystis hominis. He was treated with metronidazole for 10 days with symptom resolution, and no recurrence of diarrhea.