Imaging of Hemangiornas and Vascular Malformations in Children; Jos6e Dubois, MD, Laurent Garel, MD, Andr6e Grignon, MD, Mich~le David, MD Louise Laberge, MD, Denis Filiatrault, MD, Julie Powell, MD Our understanding of vascular lesions is confounded by the use of such complex hybrid terminology as straw- berry, capillary, juvenile, and cellular hemangiomas, cap- illary-cavernous hemangiomas, and lymphangioheman- giomas. In 1982, Mulliken and Glowacki (1) classified congenital vascular lesions into two groups--hemangio- mas and vascular malformations--according to clinical, histologic, and cytologic features. By using histochemi- cal, autoradiographic, and electron microscopic tech- niques, cutaneous lesions were sorted in two categories: hemangiomas and vascular malformations (2). Heman- giomas are characterized by proliferative and involutive phases. Vascular malformations are divided according to channel abnormalities into anomalies of capillaries, veins, arteries, lymphatics, or combined vessels. This classification system has established a better understand- ing of and led to better treatment of vascular lesions. This pictorial essay is based on our experience with 162 children with a presumptive clinical diagnosis of he- mangioma or vascular malformation who were seen from 1991 to 1995 in the multidisciplinary clinics of vascular anomalies at our institution. This article presents our ex- perience with various imaging modalities, including plain radiography, ultrasound (US), computed tomography Acad Radiol 1998; 5:390-400 1 From the Departments of Medical Imaging (J,D., L,G,, A,G,, D.F.), Hematology (M,D.), Plastic Surgery (L.L,), and Dermatology (J.P,), H6pital Sainte-Justine,3175, C6te-Sainte-Catherine, Montr6al, Qu6bec, Canada H3I 1C5. Received July 24, 1997;revision re- quested July 30; final revision received November 17; accepted No- vember 19. Address reprintrequests to J.D. ©AUR, 1998 (CT), magnetic resonance (MR) imaging, and MR an- giography, at the time of diagnosis and following drug treatments, radiologic interventions, or surgical proce- dures. Proper identification of hemangiomas and vascular malformations is crucial for the choice of therapy and for adequate follow-up. Hemangiomas are the most common rumors occurring in infancy. As many as 10%-12% of children develop he- mangiomas by the age of 1 year, with a female-male ratio of 3:1. The hemangiomas usually appear in the 1st week of life, and occasionally at birth, as a single lesion lo- cated in the face and neck (60%), trunk (25%), and ex- tremities (15%). Hemangiomas are characterized by three phases: rapid postnatal endothelial proliferation (6-8 months), variable stability, and slow involution (around 18 months to 8 years) (3). Most often, hemangiomas grow as a well-circum- scribed, strawberry-like mass, but infiltrating lesions also develop. They may involve the superficial skin layer (su- perficial hemangiomas) or the deep dermis with normal overlying skin. Histologically, in the early proliferative phase, a hemangioma is composed of plump endothelial ceils that form syncytial masses with or without a lumen. There is an increased turnover rate and augmented num- ber of mast cells. Later, in the proliferative phase, capil- lary-size lumina are often seen. During the involutive phase, there is progressive perivascular deposition of fibrofatty tissue, enlargement of the vascular lumen, and thinning of the endothelial lining, which accounts for the evolutive radiologic pattern. 390