A large left ventricular sub-mitral thrombus in the absence of sub-mitral aneurysm in a patient with colorectal adenocarcinoma

A left ventricular sub-mitral thrombus without an aneurysm is a previously unreported rare occurrence. We aim to bring attention to this finding in a case of colorectal adenocarcinoma.An early 60s-year-old female presented with bleeding per rectum, weight loss and fatigue and was found to have colorectal carcinoma with metastasis based on examination, imaging and biopsy findings. On pre-chemotherapy evaluation, a mass was seen at the sub-mitral level in the left ventricle on echocardiography and was confirmed to be thrombus by contrast-enhanced CT. Patient was started on anticoagulation and palliative therapy.Based on the clinical history, location, irregular shape, lack of capsule, pedunculation and contrast enhancement, it is highly probable that the mass is a thrombus. However, in patients with carcinoma, the common location for intracardiac thrombus due to malignancy-associated hypercoagulability is the right side of the heart and a left-sided thrombus is rarely reported. In general, left ventricular thrombi are frequently present at the apex. The sub-mitral position is unusual. Rarely, sub-mitral thrombi occur in patients with aneurysm at this location. Interestingly, our patient does not have this predisposing factor as well. There is no history of rheumatic heart disease, ischaemia, syphilis or tuberculosis, which may cause thrombi at this location less often. Reviewing the literature, no previous cases of thrombus at the sub-mitral location without aneurysm were found.