A 71-year-old woman presented with pericardial discomfort while coughing, and chest computed tomography (CT) showed a left lateral mediastinal mass. Although the mass remained unchanged in CT findings 3 months later, surgical resection was recommended because a mediastinal tumor such as thymoma or teratoma was suspected. The anterior mediastinal mass was 2.0 × 1.2 × 1.8 cm in size, with border regularity and without calcification. Its interior was partially enhanced (Fig. ), and a tortuous vessel was revealed in the thymus in enhanced CT imaging (Fig. ).\nSurgical resection was performed for the purpose of providing a definitive diagnosis and treatment. With the patient in a spinal position, partial resection of the thymus including the mass was done by utilizing a three-port, left-sided VATS approach with hoisting of the third rib. A wine-colored mass bulging from the surface of the left lobe of the thymus was identified (Fig. ) along with the communicating vessel (Fig. ), which could only be cut with an energy device. The operative time was 138 min and there was only minor blood loss. The patient was discharged on postoperative day 7 without complications.\nThe size of the excised mass was 2.3 × 1.3 × 1.8 cm, and there was no infiltration of the adjacent thymus (Fig. ). A histopathological diagnosis of CH in the thymus was made based on the marked dilated vascular channels full of blood covered with endothelial cells and without atypia (Fig. ), and the vessel was included in the mass.\nCH is not a vascular tumor, but rather a congenital vascular anomaly classified as a venous malformation in the low-flow lesion category by the International Society for the Study of Vascular Anomalies (ISSVA) [, ]. This abnormality can occur throughout the whole body, though size and site of origin vary. Some reports have noted its occurrence in patients with a venous aneurysm [, ]. Such a vascular anomaly is considered to be the result of local abnormal morphogenesis of normal vascular endothelial cells occurring before birth [], which then increases in size and exists for the lifetime of the individual without atrophy. Approximately half of the patients with CH are diagnosed at younger than 20 years old. Histopathological findings generally show cavernous or cystic venous channels with a flat single layer of endothelial cells without atypia or mitosis. The choice of treatment is dependent on the related organ and can include embolization, sclerotherapy, and surgical resection. In cases of resection, the lesion should be completely removed because residual tissue has the potential for recurrence with abnormal vessel dilation or regeneration.\nCH occurs with greater frequency in the liver, accounting for approximately 30 % of known cases, as well as in the brain and skin, whereas there are several reports of mediastinal cases in Japan []. Since it was previously thought to be a tumor, a mediastinal CH is considered to be rare, accounting for 0.5 % or less of all mediastinal tumors []. Furthermore, there are only seven reports of cases with a proven thymic origin [, , –].\nWhen occurring in the thymus, a CH may require resection for diagnosis and treatment, as it is otherwise difficult to distinguish from another type of mediastinal tumor such as a thymoma. Even though it does not generally invade the neighboring tissue, complete resection is desirable, as previously described. Cohen et al. reported that subtotal excision should be chosen if complete resection carries serious risk because there was no rapid growth noted in a case of incomplete resection and re-resection can be considered at the time of recurrence []. Extirpation by means of a median sternotomy or thoracotomy will be needed in cases with a giant mass [] or innominate vein aneurism [, ]. On the other hand, thymic partial resection using VATS is a better option for small and non-infiltrative lesions, such as seen in the present case.\nFor accurate diagnosis of CH, magnetic resonance (MR) imaging or ultrasound sonogram are often used to examine the brain, liver, and other organs. The typical imaging manifestation of CH is popcorn-like lesion with a peripheral hypointense rim so-called hemosiderin rim on T2-weighted MR images. As for mediastinal or lung vascular anomalies, enhanced CT may be very effective, as it can reveal a phlebolith in some cases of venous malformation. No phlebolith was seen in our patient, while the center of the mass was enhanced and a communicating vessel running through the thymus was detected. In addition, findings obtained with a three-dimensional image analysis system (SYNAPSE VINCENT ver. 4.0, Fujifilm Medical Inc., Japan) showed the positional relationship of the tortuous vessel and the mass on the side wall (Fig. ). We consider that such an image analysis system is helpful for diagnosis of vessel malformation, as seen in the present case.\nThe mass was resected completely but we intend to follow the present patient to note vessel changes.
A 58 years-old man presented at our emergency room with fever, cough and left thoracic pain. His past medical history was unremarkable. Blood test showed WBC and C-reactive protein elevation. He had started antibiotics therapy and, given the persistence of symptoms, CT scan was performed showing lower left pneumonia. Incidentally, a 2.5 cm mass was found in the upper anterior mediastinum, with positive contrast enhancement and a 5 mm vessel arising from left brachio-cephalic vein (, ). Because of size and position fine needle aspiration nor anterior mediastinotomy were performed. Radiologic features were consistent with thymoma that usually appears as an ovoid or lobulated, smooth, well-marginated mass, projecting over the mediastinum typically protruding unilaterally, therefore patient underwent (1) neurologic evaluation that excluded myasthenia (2) PET/CT scan that showed the absence of any pathological uptake. However, thymoma was felt to remain a diagnostic possibility and patient was referred for radical surgery, with particular attention to abnormal vascularization. He underwent left thoracoscopy and, in spite of extreme attention, during pleural dissection between mediastinum and sternum, a sudden massive bleeding occurred (about 1,500 cc) requiring emergency conversion to median sternotomy. It was then clear that the bleeding came from tumor and not from brachiocephalic vein or its branches, as initially thought. After controlling the bleeding, we removed the mass but it was necessary to sacrifice the left laryngeal nerve.\nIntra-operative emergency required significant blood transfusions and precautionary transfer in intensive care for 24 h. The patient eventually made a complete recovery. We only recorded transitory dysphonia as in case of laryngeal nerve paralysis. At specimen analysis, the cut surface seemed to have some fresh blood and the soft tissue was taupe with multifocal thrombosis in various stages of organization up to phlebolithes. Histopathologically, it was diagnosed a residual thymic tissue surrounded by lipomatous hyperplasia with venous malformation consisting essentially of a large number of dilated vessels with a single layer of endothelial cells with no signs of atypia or mitosis. Most of the channels contained red blood cells in the cavity. Margins were free. Definitive histology was a 7 cm fatty specimen enclosing a 2.5 cm in size mass diagnostic for residual thymus associated with venous vascular malformation (ISSVA classification, 2008).