Twelve cases of apparently primary @entity2698 are reported: 7 intrapulmonary and 5 extrapulmonary. These cases, taken together with 75 others already published, serve as a basis to describe the characteristics of @entity2698 . Intrapulmonary forms raise the problem of a single peripheral X-ray lesion, often detected in a routine film, with no accompanying @entity854 . Extrapulmonary forms also take the form of a well defined @entity5 with diaphragmatic or mediastinal parietal connections. Up to the present, the diagnosis has always been made at thoracotomy. It is probable that a preoperative diagnosis will be possible in the future by transbronchial biopsy. @entity575 stains and the use of the electron microscope form the basis of histological diagnosis. However it is not possible to distinguish by histology between benign and malignant forms, nor between primary or metastatic @entity2698 . It is for this reason that doubt will long persist as to the primary nature of the @entity5 and only prolonged survival of @entity1 after excision confirms that the lesion was indeed primary. Treatment is essentially surgical. New high energy radiotherapy techniques and new possibilities in chemotherapy (using adriamycin) should improve the prognosis in those forms which run a malignant course. However the standard therapeutic strategy for these rare @entity5 has yet to be defined.

[Apparently primary XXXX . Apropos of 12 cases].

@entity1 :: ('9606', 'Species') :: ['patients'] @entity575 :: ('MESH:D012834', 'Chemical') :: ['Silver'] @entity2698 :: ('MESH:D006393', 'Disease') :: ['hemangiopericytomas', 'thoracic hemangiopericytoma', 'thoracic hemangiopericytomas'] @entity5 :: ('MESH:D009369', 'Disease') :: ['tumor', 'tumors'] @entity854 :: ('MESH:D018376', 'Disease') :: ['endoscopic abnormality']
@entity2698 :: (MESH:D006393,Disease) :: ['thoracic hemangiopericytoma']
