Cardiac MRI of a right atrial fungal mass

35-year-old male patient, presented with fever, cough, dyspnea, anorexia and easy fatigability.

Work up at hospital admission showed; elevated leucocytic count. Echocardiogram was requested as clinician suspected infective endocarditis, it revealed a right atrial mass lesion. So Cardiac MR scan was requested.

Cardiac MRI was  performed by 1.5 Tesla MRI (Philips achieva scanner) at our institution;  revealing a large invasive, right atrial mass lesion, measuring (7.5 x5.8x5.9 cm (Cc xAP xTR), it showed  high signal intensity(SI) on STIR, heterogeneous intermediate SI on T1 & T2WI and heterogeneous delayed contrast enhancement with central non enhancing areas suggesting necrosis/breakdown.

This lesion was extending to the right hilar region, aortic pericardial recess, totally surrounding and mildly attenuating the right pulmonary artery and right superior and inferior pulmonary veins. The lesion extended superiorly to the right paratracheal region and causing marked attenuation of the SVC. Enlarged enhanced mediastinal Lymphnodes (right hilar, subcarinal) were also noted. In addition there were few scattered pulmonary nodules and lower lobar small consolidative patches.

CT pulmonary angiography was done; confirming attenuation of the right pulmonary artery and SVC being attenuated/occluded by the mass.

The patient underwent surgical debulking of the cardiac mass.

Pathology report revealed; fibrohyaline tissue infiltrated by florid inflammatory reaction of polymporhs, lymphocytes and neutrophils with scattered multinucleated giant cells, some engulfing spores. Sections stained with PAS stain was positive.

Intracardiac lesions are highly variable in their clinical expression and can lead to a diagnostic dilemma. Echocardiogram is the primary investigation, can help to assess mass dimensions as well as surrounding structure, however for better assessment and detailed extensions in the mediastinum, multiplanar Cardiac MRI is the superior tool, in order to fully delineate the lesion`s extensions, so as help in surgical planning and also help in characterizing the lesion with better temporal and spatial resolution. [1]

The widely known pattern of fungal heart infection is in the form of valve endocarditis, diffuse endocarditis, and/or cardiac device-related infection. However, some may present as a mass-like lesion, thus being a source of lesional thrombi. These Fungal infections have high morbidity and mortality due to their widespread nature. Making it crucial to early recognize them to proceed to prompt surgical intervention and longterm antifungal therapy in order to improve patient`s outcome.[1]

On imaging, fungal heart disease is difficult to differentiate from a thrombus or tumors due to common imaging findings. [2]

In our case, the patient had history of excision of intracranial invasive granulomatous fungal reaction few months ago, that raised our suspicion in his new lesion to be of fungal origin. Other differentials were less suspected as;

Intracardiac thrombus is avascular, and will show no contrast enhancement in MR scan.[3]

Primary cardiac angiosarcomas will have heterogeneous SI at T1WI, T2WI;  showing enhancement at first-pass perfusion due to vascularity and heterogeneous enhancement at LGE imaging due to central necrosis. [3]

Myxoma benign cardiac tumor with a predilection for the interatrial septum. [3]

Primary cardiac lymphoma is a homogeneous mass, isointense on T1- and T2-weighted images, no areas of necrosis or haemorrhage, usually accompanied by large pericardial effusions. [3]

Cardiac metastasis most commonly involve the pericardium, and there will be history of primary malignancy. [3]

According to DeFilippis et al, infective fungal masses do not have robust central perfusion on cardiac MRI (which is found in many neoplastic lesions). However, fungal lesions can demonstrate delayed peripheral enhancement around the mass, which is a nonspecific imaging feature that can suggest an infectious cause.[2]

Our take home message: It is highly recommended to use cardiac MRI in cases of cardiac masses to better delineate the extensions and characterize its tissue nature.