Papillary fibroelastoma of the papillary muscle-a case report on a rare entity and sometimes a delayed diagnosis.

Background Papillary fibroelastoma, generally affecting the valve endocardium, is one of the most common benign cardiac tumours. Although rarely reported, atypical localization of such tumours complexifies diagnosis and might negatively impact patient outcomes due to late detection.Case Summary We present the case of a 69-year-old female patient presenting for a check-up consultation and reporting symptoms of dysesthesia, aphasia, and dizziness. The patient had a history of atrial fibrillation on anticoagulation with rivaroxaban starting 6 years prior to presentation. Further examination using transthoracic and transoesophageal echocardiography revealed a hyperechogenic structure at the level of the subvalvular apparatus of the mitral valve. Interestingly, when cardiac MRI was subsequently performed, this diagnosis could not be confirmed. This discrepancy might be linked to the lower spatial and temporal resolution compared to transoesophageal echocardiography, or transthoracic echocardiography with a high-frequency probe. To further investigate the symptoms of dysesthesia, aphasia, and dizziness, a cerebral MRI was performed which revealed multiple, bilateral ischaemic lesions. Considering the findings and the symptoms of the patient, the choice was made to perform explorative surgery. Intraoperatively, an 8-mm structure was identified and removed from the basis of the posteromedian papillary muscle. Histological examination revealed a papillary fibroelastoma. The patient was discharged on postoperative day 10. At follow-up, there was no report of neurological symptoms.Discussion This case shows a highly atypical localization of a rare cardiac tumour and exemplifies the importance of multimodal diagnostic imaging prior to cardiac surgery.