Hemangiomas are benign tumors  originating either from endothelial cells of blood vessels, or from pericytes located on the outer side of the vascular wall. They appear in two forms: capillary and cavernous. Capillary hemangiomas are usually on the skin; they vary in size and shape, and cause esthetic distortions. Histologically, they are characterized by a large number of anastomotic vascular spaces of irregular arrangements and sizes, lined with endothelial cells, with the lumina filled with blood or thrombi. Cavernous hemangiomas are found in skin, liver, kidney, breast, muscles, intestinal wall, brain and bones. Histologically, they are characterized by vascular spaces lined by endothelial cells. These are wider than the capillary types, occasionally taking the form of a cavern. Both types, capillary and cavernous hemangiomas, occur in the uterus. Capillary hemangiomas are usually restricted to the endometrium, whereas the cavernous form involves the uterus in a diffuse fashion. Complications such as thrombosis with organization and calcification may occur.
Hemangiomas of the uterus may occur at any age; the youngest patient reported in the literature was 14 years old . Such hemangiomas may be diffuse or localized. The diffuse form usually involves all layers of the uterus, whereas a localized hemangioma can present as an endometrial polyp, or be restricted to the myometrium. It can rarely present as a cavernous hemangiomatous polyp .
Physiological changes related to pregnancy involve hypertrophy of the myometrium, but not hemangiomatosis . During early pregnancy, cavernous hemangioma of the gravid uterus is a serious condition, and may not be detected. Clinically, these vascular lesions are usually asymptomatic, but might bleed spontaneously or following curettage; they can be associated with menstruation or termination of pregnancy. That the diagnosis is not usually considered is due to the rarity of this condition and vagueness of the symptoms. A few cases have been confused with disseminated intravascular coagulation (DIC) or uterine atony. DIC leads to the formation of fibrin thrombi in the microvasculature of the body, including the alveolar capillaries in the lungs. There were no microthrombi identified in our case; instead, the thromboemboli were evident in the small- to medium-sized pulmonary arteries. In a variation of the theme, in extremely rare cases, giant hemangiomas could be associated with an unusual form of DIC, in which thrombi form within the neoplasm. This is attributed to stasis and recurrent trauma to fragile blood vessels. It is difficult to intellectualize if such a rare phenomenon could have been contributory to the cavernous thrombosis in this case. A high index of suspicion is required both of radiologist and obstetrician in case of heavy bleeding per vaginam because delay in diagnosis can result in significant blood loss requiring a hysterectomy .
USG can reveal a thickened uterine wall and a mixed-echo texture suggestive of cavernous changes with turbulent flow . Doppler, MRI and computed tomography imaging may be used in conjunction with USG for diagnosis. Arteriography has been successfully used in the diagnosis of unexplained cases of extensive refractory uterine bleeding in young patients. Therapeutic embolization of feeding vessels by liquid polymers helps preserve the reproductive capability with uncomplicated pregnancy .
Conservative treatments including carbon dioxide laser excision, knife excision, cryotherapy, radiotherapy, electrocauterization and uterine embolization have been attempted with varying results. In cases of uncontrolled bleeding especially during operative delivery, or not responding to conservative treatment, a hysterectomy is imperative. Successive pregnancies have been reported in women harboring cavernous hemangiomas of the uterus .
In cavernous hemangiomas of the uterus, the uterine wall is partly or completely transformed into cavern-like arteriovenous fistulas as a result of a proliferation of arterial and venous vessels of various sizes which later replace the normal myometrium . A histopathological diagnosis of cavernous hemangiomas of the uterus usually occurs after a hysterectomy showing vascular spaces limited by endothelium assuming a cavern-like shape separated by connective septa.
Cavernous hemangiomas may be complicated by thrombosis, and such patients may develop DIC  due to platelet entrapment by abnormally proliferating endothelium within the hemangiomas. In pregnant women with congenital hemangiomas, hormonal alterations and physiological increases in blood volume may play contributory roles. Similar changes during pregnancy resulting in venous thrombosis in the myometrium have also been reported .
This is the first case of a thrombosed cavernous hemangioma of the uterus resulting in fatal pulmonary thromboemboli. Grossly, a 400g spongy and hemorrhagic uterus was identified. Histopathological examination revealed multiple vascular spaces within the myometrium lined by endothelial cells. Immunohistological examination with a CD31 stain for vascular endothelium associated antigen confirmed the endothelium-lined vessels, a few of which were filled with thrombi. The histologic features were in accordance with the previously reported cases of cavernous hemangioma of the uterus [1, 2]. Histological study of the lumina revealed multiple fresh thromboemboli without organization in both small- and medium-sized pulmonary arteries in the right upper and lower lobes with adjacent areas of fresh hemorrhagic infarction. Features of acute and early DAD and early organization with fibrosis were also identified. The sources of the emboli were the extensive thrombosed cavernous myometrial hemangiomas, as no thrombi were identified in the popliteal or in other veins. The migration of these emboli through the channels of uterine, hypogastric and common iliac veins resulted in pulmonary embolism.
The proximate cause of death was attributed to terminal thromboemboli from cavernous hemangiomatosis of the myometrium and pulmonary infarcts with severe DAD. Although thrombosis of the cavernous hemangiomas has been previously reported [9, 10], subsequent embolization was present in those cases.