A case report of left ventricular outflow tract obstruction due to early growth of a calcified amorphous tumour despite normal renal function.

Background: Calcified amorphous tumours (CAT) are non-neoplastic cardiac masses that have been the focus of several recent studies. Moreover, CAT is frequently observed in women and in patients undergoing dialysis. Case summary: A woman in her 70 s with normal renal function was referred to our hospital with a chief complaint of shortness of breath upon effort. Echocardiography and contrast-enhanced CT revealed a cardiac mass with calcification in the intervalvular fibrosa (IVF) of the anterior mitral valve, resulting in left ventricular outflow tract (LVOT) obstruction. One year later, the cardiac mass expanded, and the LVOT obstruction worsened. The patient underwent surgical resection of the mass and double-valve replacement with reconstruction of the IVF (commando operation) and myectomy. Histological examination confirmed that the mass was CAT. Discussion: We encountered a patient who underwent valve replacement and a commando operation due to rapidly progressive CAT and consequent progression of LVOT obstruction despite normal renal function. In patients with normal renal function, factors other than calcium and phosphate metabolism contribute to the formation of CAT. Understanding the accumulation of CAT is crucial for understanding its pathogenesis.