[Hemangiopericytoma (extrapleural solitary fibrous tumour). Exemplified and discussed on the basis of two cases].

BACKGROUND: Hemangiopericytoma was first mentioned in 1942. It is a very uncommon potentially malignant vascular tumour which can occur at every site of the body. According to the WHO, most of the tumours formerly diagnosed as hemangiopericytomas are considered to be extrapleural solitary fibrous tumours. The diagnosis of "hemangiopericytoma" is now only determined if a constant histological picture of hemangiopericytoma is present. The tumour can lead to lymphogenous or hematogenous metastasis. The major location of occurrence is the cutis and subcutis. It originates from the pericytes of the vascular wall. This is reflected in its vascular character and therefore the hemangiopericytoma might clinically be mistaken for a hemangioma. CASE REPORTS: Patient 1: 60 years, female; diagnosis: malignant suboccipital hemangiopericytoma; size: 4.9 x 4.5 x 4.2 cm; pT1bNXMX L0 V0 Pn0; stage IA; grading G1; R0.Patient 2: 38 years, male; diagnosis: benign hemangiopericytoma infraorbital left; size 1.5 x 1.5 x 1.5 cm. DISCUSSION: Most often the hemangiopericytoma becomes clinically conspicuous as a slowly growing, painless swelling. The consistency ranges from soft to dense, and the color is greyish-blue. The slow and painless growth carries the danger of a clinically wrong diagnosis and thus delayed therapy. The histological diagnosis of hemangiopericytoma is determined by biopsy. Besides histology, MRI and angiography are methods that can be employed to diagnose hemangiopericytoma. The therapy of choice is the complete tumour-resection with a safety margin of 1 cm. In the case of an aggressive growth pattern, adjuvant postoperative radiotherapy is recommended. Until now there has been no documented specific therapy concept for managing incomplete resection and the occurrence of metastasis. There are reports about chemo- and radiotherapy either on their own or combined which evidence differing degrees of success. Lifelong monitoring is necessary because recrudescences and metastases can occur even decades later.