**Abstract**

Infection in humans by the intestinal protozoan of cockroaches and termites called *Lophomonas blattarum* has been diagnosed in respiratory infections of children aged 2–5 years contaminated orally or by air, with cysts or trophozoites contained in the feces of the cockroach *Periplaneta americana*. In respiratory infections of adults, it is difficult to diagnose since the cyst or trophozoite is not recognized as a human pathogen and is only related to immunosuppressed patients, transplant patients with severe lung disease and those living in poor and unhealthy sanitary conditions. Normally, its presence is manifested with fevers of 38–39°C, cough with thick expectoration, respiratory insufficiency and pulmonary abscesses. The laboratory diagnosis is mainly based on bronchoscopic cytologies and bronchoalveolar lavage biopsies. The case in question is about a 60-year-old male. Single, he lives alone, with a diagnosis of 9 baths behind non-Hodgkin lymphoma, undergoing treatment with radiotherapy and chemotherapy. For edema after treatment, thoracentesis and pericardiocentesis were performed, as well as gastrostomy, which he maintained for 1 year. He started with throat discomfort, followed by production of productive cough without blood, general weakness, and difficulty breathing, with apparent diagnosis of possible respiratory failure due to mycobacteria. It was possible to visualize the protozoan, in fresh preparations of bronchial aspirate and expectoration in wet assembly with saline solution and stained with Pap smears, Harris Hematoxylin and Eosin (H/E), and Giemsa.

**Keywords:** American periplaneta, multiflagellated protozoan, bronchopulmonary lophomoniasis, endocommensal, immunosuppression
