RESPIRATORY INFECTION ASSOCIATED WITH LOPHOMONAS SPP. IN A PATIENT WITH SUSPECTED LUNG NEOPLASM

A 76-year-old woman was admitted with progressive dyspnea that had worsened abruptly over the previous seven days and difficult-to-control bronchospasm. She had a history of asthma since childhood, completed treatment for tuberculosis in the 1970s, and worsening symptoms over the last five years, recurrent and often attributed to asthma exacerbations or infections. On outpatient investigation, bronchoalveolar lavage culture revealed flagellated protozoa of the genus Lophomonas spp. During hospitalization, immunosuppressive conditions such as HIV, hepatitis, autoimmune diseases, diabetes and hypothyroidism were ruled out. Tests for tuberculosis (smear microscopy, PCR) were negative. Chest CT showed bilateral reticulonodular infiltrates, left pleural effusion, a 65 mm mass in the left upper lobe and paratracheal lymphadenopathy, suggesting neoplasia or disseminated infection. Pleural drainage revealed exudative fluid with 71% neoplastic cells, indicating probable cancer. Laboratory tests showed elevated LDH, consistent with exudate. Given the clinical picture, metronidazole 500 mg every 8 hours for 14 days was started to control the protozoal infection. The patient was referred to oncology for diagnostic confirmation and staging. This case describes an elderly, frail patient with worsening respiratory status, signs of possible neoplasia and culture positive for Lophomonas spp. Therapy with metronidazole was instituted, with oncology follow-up for further diagnostic procedures. Lophomonas spp. is a flagellated protozoan regarded as a cause of respiratory infections, especially in immunosuppressed patients. Transmission occurs via inhalation of environmental cysts or ingestion of contaminated food. Symptoms include cough, low-grade fever and dyspnea, and may be accompanied by leukocytosis and eosinophilia. Radiological findings range from reticular to consolidative infiltrates. Diagnosis is based on microscopic visualization of cysts in respiratory samples, mainly with Giemsa staining, as there is no in vitro culture. Treatment with metronidazole (1,500–3,000 mg/day for 7–14 days) is highly effective, with resolution in more than 90% of cases.