[Video-assisted Thoracic Surgery of an Hourglass Transmural Lipoma;Report of a Case].

Hourglass transmural lipomas are rare. A 79-year-old male was referred to our hospital due to an abnormal shadow incidentally found on a chest X-ray 6 years ago. Chest computed tomography and magnetic resonance imaging revealed a well-defined fatty mass like an hourglass, penetrating the right 4th intercostal muscle. The tumor tended to grow slightly and we considered the possibility of well-differentiated liposarcoma. We performed a complete resection of the tumor with partial resection of the 5th rib with the assist of thoracoscopy. The chest wall was reconstructed using an expanded polytetrafluoroethylene (ePTFE) sheet. The tumor was 55×52×47 mm in size and histologically diagnosed as an intermuscular lipoma. Thoracoscopy was useful to determine the excision line.