Rapid daily expansion of highly mobile intracardiac calcified tissue: a case report.

Background: A calcified amorphous tumour (CAT) is a non-neoplastic mass lesion arising within the cardiac chamber. CATs are rare but are a common cause of organ embolism. In the present study, we experienced a case of an intracardiac mass with calcification that, in contrast to a typical CAT, suddenly appeared and rapidly expanded without an inflammatory response based on pathological findings. Case summary: A 58-year-old Japanese man undergoing peritoneal haemodialysis had a high-echoic mobile mass (15 × 6 mm), which was not visible on the transthoracic echocardiography (TTE) approximately a month earlier, in the left ventricular outflow tract noted on TTE performed during a close examination for fever. Although multiple blood cultures were negative, ampicillin/sulbactam and ceftriaxone were initially administered because of suspected blood culture-negative endocarditis. The mass rapidly enlarged (22 × 5 mm) over the following days. A CAT was suspected and resected based on imaging findings with calcification; however, the pathological findings did not indicate inflammation and fibrin that are typically found in CATs. Echocardiography performed 12 months after the resection showed no recurrence. Discussion: This intracardiac calcified tissue had several similar features to a CAT. However, the initial presentation, enlargement rate, and pathological features of the tissue differed from that of a typical CAT. Although it is unknown whether this mass is a subtype of CAT, when an intracardiac calcified tissue is detected using an imaging test, careful follow-up or early surgical resection should be considered given the possibility of rapid tissue enlargement and embolism caused by the mass.