Cavernous hemangioma is a kind of venous malformation that occurs when blood flow is low at birth. It mostly grows on the head, face, oral mucosa, limbs, liver, spine and other parts of the body but rarely grows in the thymus. When the mass becomes enlarged, it can constrict the heart and nearby blood vessels, causing chest tightness, cough, breathing difficulties and other symptoms. Histologically, hemangiomas are congenital benign tumors or vascular malformations that generally originate from residual embryonic angioblasts and are caused by abnormal embryonic vascular development[12]. Ninety percent of hemangiomas are cavernous hemangiomas and capillary hemangiomas, some of which disappear with age. Cavernous hemangiomas are rare vascular malformations. Microscopically, the hemangioma is composed of abnormally dilated blood vessels lined with endothelial cell monolayers. Phlebolith is the characteristic manifestation of thymic cavernous hemangiomas, but only 10% of cases show phlebolith on CT scans. CT scans can show round or oval soft tissue masses in the anterior mediastinum, and they have clear borders and the same density. Calcification, which is caused by thrombosis, can be detected within the mass. Dynamic enhanced CT scans can reveal progressive enhancement in most but not all tumors.
Thymic cavernous hemangiomas should be differentiated from thymomas, teratomas and lymphomas. Thymomas are common primary tumors located in the anterior mediastinum, accounting for approximately 20–40% of mediastinal tumors. They always originate from thymic epithelium. Thymomas mainly occur in people aged 50 to 60 years old, with no significant differences in prevalence between men and women. Most patients have no obvious clinical symptoms, but chest X ray scans can reveal the tumors. When tumors grow, they oppress nearby tissues and organs, often causing chest distress, chest pain and other types of discomfort. CT scans can reveal round or oval soft tissue masses in the anterior mediastinum, which can be seen more clearly when enhanced. Therefore, it is difficult to distinguish thymic cavernous hemangiomas from thymomas in clinical and imaging examinations. Shen C[3] et al misdiagnosed one case of thymic cavernous hemangioma as thymoma. Th postoperative pathology results revealed that it was a cavernous hemangioma.
Therefore, surgical resection of thymic cavernous hemangiomas should be performed as soon as possible. Thoracotomy can be performed for larger tumors or tumors that constrict nearby blood vessels, while thoracoscopic surgery can be performed for smaller tumors. Careful intraoperative separation is needed to avoid massive hemorrhage caused by vascular injury[13]. A review of the literature found that all the 10 patients underwent surgical treatment and recovered well. However, The patient had both a thymus hemangioma and a renal carcinoma in our case. For patients with thymic cavernous hemangioma complicated with renal carcinoma, no such report has been found in the literature review. We adopted a relatively conservative treatment plan, namely minimally invasive resection of thymic cavernous hemangioma, and laparoscopic radical nephrectomy after the condition was stabilized. It is still uncertain whether simultaneous thoracoscopic laparoscopic surgery is feasible in these patients. More research is needed.