Abstract Body (Do not enter title and authors here): Background:
Mitral annular calcification (MAC) is a common incidental finding associated with advanced renal dysfunction, hyperlipidemia, hypertension, or abnormal calcium metabolism. Caseous mitral annular calcification (CMAC) is a less common MAC variant involving central liquefaction necrosis, which results in a paste-like substance consisting of calcium, fatty acids, and cholesterol.

Case description:
A 64-year-old female presented to clinic with chronic shortness of breath and fatigue that started after COVID-19 pneumonia in 2021. As part of the initial evaluation, a transthoracic echocardiogram (TTE) was done, which revealed moderate annular calcification, 3+ mitral valve regurgitation, and a 1.8x1.5 cm echogenic mass on the posterior mitral annulus, concerning for possible fungal vegetation. Further multimodality imaging was pursued. Transesophageal echocardiogram confirmed the presence of a 2.0x1.7 cm cystic mass but demonstrated normal mitral valve function. Cardiac MR further identified a 1.2x0.8x1.5 cm hypointense mass, with surrounding late gadolinium enhancement, suggesting an associated inflammatory/degenerative process. Gated cardiac CT scan showed a mass with ring-like dense peripheral calcification and low central attenuation. Overall, findings from multimodality imaging were most consistent with CMAC. In the present case, the patient was monitored conservatively, as her symptoms of shortness of breath improved, and she did not experience any associated complications.

Discussion:
The present case demonstrates an incidental finding of an echogenic mass on the posterior mitral annulus, later identified as CMAC. Initial imaging with TTE helps evaluate for CMAC. However, on TTE alone, CMAC is often misdiagnosed with other conditions, including intracardiac tumors, abscesses, vegetations, or thrombi, and more advanced imaging is often recommended. On cardiac MR, CMAC is usually hypointense due to the elevated calcium content and may have surrounding late gadolinium enhancement due to associated inflammation. On gated cardiac CT, CMAC presents with a hyperintense rim due to calcification and a hypointense center consistent with central necrosis. As in this patient, CMAC is usually a benign condition that can be monitored conservatively. Indications for invasive intervention include significant valvular dysfunction, embolization, or conduction abnormalities. Multimodal imaging can aid in appropriate diagnosis to mitigate unnecessary interventions.