Solitary fibrous tumour and haemangiopericytoma: evolution of a concept

Abstract

Haemangiopericytoma (HPC) was described in 1942 by Stout and Murray as a distinctive soft tissue neoplasm, presumably of pericytic origin, exhibiting a characteristic well‐developed ‘staghorn’ branching vascular pattern. Over the years, it appeared that this growth pattern was a non‐specific one, shared by numerous, unrelated benign and malignant lesions, and that HPC was better considered as a diagnosis of exclusion. Three categories of lesion may now be individualized within the heterogeneous group of HPC‐like neoplasms. The first category corresponds to those non‐HPC neoplasms that occasionally display HPC‐like features (e.g. synovial sarcoma). Lesions belonging to the second category show clear evidence of myoid/pericytic differentiation and correspond to true HPCs. They generally show a benign clinical course, and include glomangiopericytoma/myopericytoma, infantile myofibromatosis (previously called infantile HPC), and a subset of sinonasal HPCs. The third category is the solitary fibrous tumour (SFT) lesional group, which includes fibrous‐to‐cellular SFTs, and related lesions such as giant cell angiofibromas and lipomatous HPCs. In practice, any HPC‐like lesion can be allocated to one of these categories, leaving the ill‐defined ‘haemangiopericytoma’ category empty.