The “pseudo-pulmonary AVM sign”: an aid to the diagnosis of histoplasmosis and differentiation from pulmonary arteriovenous malformations

The diagnostic algorithm for histoplasmosis highlights the importance of imaging and emphasizes the role of the radiologist in the diagnostic workup. Here we describe a case series of patients with a novel sign of lung involvement in histoplasmosis which we have coined the Pseudo-Pulmonary Arteriovenous Malformation (PAVM) sign, the usage of which would help in the imaging diagnosis of histoplasmosis aid by distinguishing it from PAVMs. PAVMs carry risk for serious complications such as systemic emboli and may require treatment; whereas, histoplasmomas do not. Differentiation of histoplasmosis from other diagnoses can be made with laboratory studies, but may require bronchoscopy, biopsy, or both. Meanwhile, PAVMs should not be biopsied due to risk of bleeding. For these reasons, distinguishing PAVMs and histoplasmosis radiologically therefore greatly impacts clinical management, and it is important for radiologists to be aware of this appearance of histoplasmosis to avoid misinterpretation as PAVM and effectively inform clinical care.