Pulmonary tularemia presenting as bilateral pulmonary nodules during BEP chemotherapy for testicular embryonal carcinoma: A diagnostic challenge

Pulmonary tularemia is a rare zoonotic infection caused by Francisella tularensis that can mimic malignancy on imaging. This report presents a 38-year-old man with testicular embryonal carcinoma who developed multiple bilateral pulmonary nodules approximately 2 and a half weeks after initiating bleomycin, etoposide, and cisplatin (BEP) chemotherapy. The imaging differential diagnoses included pulmonary metastatic disease, bleomycin-induced pulmonary toxicity (BIP), and infection. Although the aggressive biology of embryonal carcinoma made pulmonary metastasis a significant concern, the poorly marginated nodule morphology and peribronchovascular distribution were atypical for hematogenous metastasis, and normalized serum tumor markers argued against active metastatic disease. Positive F. tularensis serology combined with zoonotic exposure history ultimately established the diagnosis of pulmonary tularemia. The patient had epidemiological exposure through outdoor dogs that hunted small animals. Following treatment with oral ciprofloxacin for 10 days, follow-up CT at 1 month demonstrated significant improvement with decreased size and number of pulmonary nodules and pleural effusions. This case highlights the importance of recognizing atypical nodule morphology, correlating imaging findings with tumor markers, and considering the timing of nodule appearance relative to chemotherapy to avoid misdiagnosis, inappropriate staging, and unnecessary treatment escalation in oncology patients.