Hand Knob Stroke Due to an Embolism of a Metastatic Tumor in the Left Atrium.

A stroke confined to the precentral hand knob is uncommon and often mistaken for peripheral neuropathy. Embolic mechanisms are common, most frequently arising from large-artery atherosclerosis, but unusual sources may occur. We describe the case of a 68-year-old man with weakness restricted to the ulnar-sided fingers due to a small infarct in the medial precentral hand knob. Cervical vascular imaging was unremarkable, but echocardiography revealed a highly mobile left atrial mass arising from the ostium of the left upper pulmonary vein. The patient had a history of sublingual gland adenoid cystic carcinoma with metastases to the mediastinum, lungs, and liver. CT confirmed the atrial mass as contiguous with mural thickening, consistent with intracardiac metastasis. Given disseminated disease, supportive care was chosen. To our knowledge, this is the first reported case of a hand knob infarct caused by an embolism from a mobile left atrial metastasis of salivary gland origin, highlighting the need to consider metastatic cardiac tumors, particularly in patients with malignancy and unexplained cortical infarcts.