Angiomatosis

A capillary haemangioma is composed solely of capillaries. Such a tumour with widely dilated capillaries is called a cavernous haemangioma. Vascular tumours with thicker walls and smooth muscle cells are called venous haemangiomas (Fig.1). Capillary haemangiomas in which the endothelial layer undergoes prominent proliferation are called benign haemangioendotheliomas; those with proliferation of pericytes are benign haemangiopericytomas.

The best known variety of benign haemangiopericytoma is the glomus tumour, which is typically located beneath the fingernail. Radiographs may reveal an eccentric intraosseous lucent lesion or cortical erosion in the terminal phalanx. On ultrasonography, hypoechoic masses are observed, and MR imaging shows nodules of low signal intensity on T1-weighted spin-echo images and of high signal intensity on T2-weighted images (Fig.2). Tumour recurrence is rare.

Bacillary angiomatosis is characterized by the presence of numerous bacteria and vascular proliferation in affected tissues. The organisms causing bacillary angiomatosis and the related disorder bacillary peliosis are similar to those causing cat-scratch disease. Patients with human immunodeficiency virus (HIV) infection may develop bacillary angiomatosis; characteristic findings include multiple angiomatous cutaneous papules, skin lesions typical of Kaposi's sarcoma, cellulitis and subcutaneous nodules. The dominant radiographic feature of the bone lesions is osteolysis, associated with an adjacent soft tissue mass.

Other examples of benign angiomatoses include the cirsoid aneurysm, venous racemose aneurysm, diffuse angiomatosis, lymphangioma and lymphangiopericytoma. Some of these tumours occur as part of syndromes: the Kasabach Merritt syndrome, the blue rubber bleb naevus syndrome, cystic hygroma and Maffuccis syndrome.

The malignant counterparts of some of these tumours (angiosarcomatoses) are much less frequent; malignant haemangioendothelioma, malignant haemangiopericytoma, and lymphangiosarcoma are examples. A rare skeletal disorder, cystic angiomatosis, exhibits visceral involvement and widespread cystic bone lesions.

Radiographic features of angiomatoses and related lesions may include soft tissue masses with circular phleboliths, bone involvement and joint abnormalities. With MR imaging, haemangiomas located within muscle are poorly marginated on T1-weighted MR images but well marginated on T2-weighted images. Sometimes large amounts of fatty tissue are present, making these tumours indistinguishable from a lipoma.

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