Pseudoaneurysm of internal mammary artery caused by pulmonary actinomycosis.

Although internal mammary artery pseudoaneurysms are a rare vascular abnormality, they are sometimes seen after sternotomy, diagnostic and therapeutic vascular access or penetrating chest trauma. To our knowledge, internal mammary artery pseudoaneurysm caused by pulmonary actinomycosis has not been reported previously. We report a case of pseudoaneurysm of the left internal mammary artery caused by pulmonary actinomycosis. A 50-year-old woman initially presented with clinical and radiological features of pneumonia, for which she was treated empirically with antibiotics. Later, she developed haemoptysis along with pain and swelling in the left upper chest wall. Multidetector CT (MDCT) with CT angiography showed a cavitating mass in the left upper lobe of the lung that infiltrated into the chest wall and a pseudoaneurysm of the left internal mammary artery. Imaging suggested that the lung mass resulted from pulmonary actinomycosis, which was confirmed by the histopathology of a fine-needle aspiration specimen.