[An unusual lesion of the mediastinum: angiomatosis or diffuse hemangioma].

Angiomatosis are rare benign vascular lesions representing almost 4% of vascular tumours in children and adolescent. These lesions occur in soft tissue and are clinically extensive, covering large parts of the body in a continuous pattern. Limbs are classically involved. The incidence is high in childhood and adolescence. The authors report an original case of angiomatosis or diffuse haemangioma located in the anterosuperior part of the mediastinum in a 17 year old girl. The patient consulted for increasing dyspnoea starting two years earlier. At medical imaging, calcified tumoral mass measuring 60 mm situated in the anterosuperior mediastinum was objectivated. The mass did not involve bony nor chondral structure. Teratoma or thymoma was suspected. At operation the whole tumor was resected with adherent pericardium. At histological examination, the lesion showed the presence of vascular structures inside fibro muscular and fatty tissue mixed with multiple nerve sections. In the lesion, venous walls were remarkably thick and sometimes picked or surrounded by multiple micro vessels. A Hamartomatous or proliferative origin may be discussed. The multiple components supports a hamartomatous origin, especially because of the unexpected presence of nervous elements. A proliferative process trapping preexisting vascular and nervous elements may be also considered. Furthermore, the lesion may represent a diffuse mesenchymatous proliferation as suggested by the presence of adipose tissue or glomic cells. Additional studies based on cytogenetics could surely improve the understanding of this lesion.