Invasive balantidiasis presented as chronic colitis and lung involvement.

A unique case of chronic balantidiasis is described, presenting with chronic colitis and inflammatory polyposis of the rectum and sigmoid colon and an intrapulmonary mass. Histology of the colonic polyps showed Balantidium coli, and both Aspergillus and Balantidium coli were found in the aspirate of the pulmonary mass. The patient was treated with doxycycline HCl 100 mg/day for 10 days with complete clinical recovery and marked improvement of the endoscopic appearance of the colonic mucosa.