Coil embolization of bilateral internal mammary artery aneurysms in the setting of a heterozygous missense variant of unknown significance in COL5A1 and fibromuscular dysplasia

Internal mammary artery aneurysms are rare but serious clinical entities. Rupture results in hemothorax and can be life threatening. Most reported cases are pseudoaneurysms secondary to iatrogenic or traumatic causes. Noniatrogenic, nontraumatic, true internal mammary artery aneurysms have most commonly been associated with vasculitides or connective tissue disorders; rare cases have been deemed idiopathic. We describe a rare case of bilateral internal mammary artery aneurysms—successfully treated with coil embolization—in the setting of heterozygosity for a missense variant of unknown significance in the COL5A1 gene and multifocal fibrodysplastic changes on angiography.