Mycotic Pulmonary Artery Aneurysm Mimicking a Rasmussen Aneurysm

Mycotic aneurysms arising from the pulmonary arteries are rare; only a few cases have been reported. Staphylococcus and Streptococcus species are the most common causative pathogens. Mycotic aneurysms are seldom clinically apparent unless as a sequela of adverse procedural complications. They carry high morbidity and mortality if not treated expeditiously.

We present the case of a 37-year-old male with bacteremia and bronchopneumonia associated with a pulmonary artery mycotic aneurysm. The case was confounded by clinical features mimicking a Rasmussen aneurysm. We discuss distinctive imaging features, disease mechanism, typical presentation, and management.

While mycotic aneurysms are uncommon, certain clinical scenarios warrant consideration of the diagnosis, such as a history of intravenous drug use, bacterial endocarditis, and immunocompromise. Rapid identification is critical to prevent life-threatening complications such as vessel rupture. Computed tomography allows for an accurate and timely diagnosis, and interventional embolization is a fast, minimally invasive curative treatment. Given similar risk factors and presentation, a mycotic aneurysm can be indistinguishable from a Rasmussen aneurysm; therefore, appropriate precautions should be taken while adequate microbiologic assessment is performed.