Introduction: Sinusoidal hemangioma (SH) was described by two pathologists, Calonje and Fletcher, in 1991. This uncommon cutaneous benign vascular lesions with distinctive histologic features was considered a subset of lesions known as "cavernous hemangiomas". It is made of dilated interconnecting ("sinusoidal"), thin-walled channels with a single-layered lining endothelium and a lobular architecture.
Patients and methods: Clinical, radiological (CT, MRI and arteriography), evolutive, and histologic data of 4 patients, whose lesions appeared very similar clinically and histologically, were reviewed and compared to the patterns of the so-called SH.
Results: There were 2 males and 2 females. Lesions had an infantile onset in 3 (congenital in 2). They exhibited a protracted course over years in the 4, and they all invaded the right forehead, eyelids and orbit areas. Clinically, they appeared as multilobulated, building, firm tumors under a normal shiny skin. Radiologically, lesions were strikingly nodular, with criteria of slow-flow vascular lesions on MRI and arteriograms. Histologically, all lesions were comprised of well-circumscribed nodules with a lobulated architecture, made of greatly dilated, blood-filled, thin-walled vascular channels, with scanty fibrous stroma between them. Interconnecting channels had the distinctive sinusoidal pattern. There were some elongated pseudopapillary structures. Islands of spindle cells were noted in 2 lesions.
Discussion: On the one hand histologic features of the lesions in our 4 patients are identical to those described by Calonje and Fletcher as SH, a lesion not to be confused with classic, involuting-type, hemangioma of infancy and childhood, and with venous or lymphatic malformations of the same location. SH fits into the group of lesions defined by pathologists as "cavenous hemangiomas". On the other hand the lesions in our 4 patients differed from the clinical description of SH as a solitary acquired small (less than 3 cm) nodule in adults. Otherwise the four lesions described herein constitute a distinctive clinicopathologic entity with a striking aggressive local growth although there is a histologic malformative pattern. The presence in 2 cases of islands of spindle cells led us to discuss the differences with spindle cell hemangioendothelioma.