title: Solitary fibrous tumour presenting with a single bone metastasis: report of six cases and literature review.
abstract: BACKGROUND
  Solitary fibrous tumour (SFT) is a rare soft tissue sarcoma with a low metastatic potential. A higher metastatic rate is observed in the high-grade/dedifferentiated variant. The most common expected site of distant spread are the lungs and the liver. Bone involvement is generally viewed as a late stage of disease spread. We report on a retrospective series of SFT patients relapsing with a single distant bone recurrence as first metastatic event, without evidence of other organ involvement.
  
  
  METHODS
  All patients affected by a single distant bone metastasis from SFT as first distant event, without any evidence of other site of metastasis, observed at our Institution, were considered. Bone involvement from SFT was pathologically assessed in all cases and confirmed by expert pathologists. A total of six patients were retrospectively identified. Primary tumour arose from the meninges in four patients, from soft tissues in two. Bone metastases were located to the vertebrae, the hip, the acetabulum and the rib. In all cases, bone relapse was the first event, with one patient presenting a local relapse. Median time from the primary tumour and the evidence of bone relapse was 40 months (range 0-58). In 2/6 patients bone metastasis was treated with radiotherapy (RT), in 2/6 with surgery, in 2/6 with surgery plus RT. At a median follow-up of 55 months (range 23-88), 5/6 patients are alive (2/5 without disease, 3/5 with multicentric metastatic disease) and one is dead of disease. 2/6 patients did not relapse after the treatment of the bone metastasis.
  
  
  CONCLUSIONS
  This small series in a relatively rare histology suggests that isolated, possibly late, bone metastases are a plausible scenario, in particular in meningeal SFT. Notably, new bone lesions in a patient with a history of SFT should be always investigated. Exclusive local treatments may be an option, though collection of such series would be needed to define the best treatment strategy.
authors: Adult Mesenchymal Tumour & Rare Cancer Medical Oncology Unit, Cancer Medicine Department, Fondazione IRCCS Istituto Nazionale Tumori, via G. Venezian, 1, 20133 Milan, Italy.
authors: Vittoria
authors: V
authors: Colia
authors: Adult Mesenchymal Tumour & Rare Cancer Medical Oncology Unit, Cancer Medicine Department, Fondazione IRCCS Istituto Nazionale Tumori, via G. Venezian, 1, 20133 Milan, Italy.
authors: Salvatore
authors: S
authors: Provenzano
authors: Department of Radiology and Radiotherapy, Fondazione IRCCS Istituto Nazionale Tumori, Milan, Italy.
authors: Carlo
authors: C
authors: Morosi
authors: Department of Diagnostic Pathology and Laboratory Medicine, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy.
authors: Paola
authors: P
authors: Collini
authors: Department of Diagnostic Pathology and Laboratory Medicine, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy.
authors: Salvatore Lorenzo
authors: SL
authors: Renne
authors: Laboratory of Experimental Molecular Pathology, Department of Diagnostic Pathology and Laboratory Medicine, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy.
authors: Paolo G
authors: PG
authors: Dagrada
authors: Department of Radiology and Radiotherapy, Fondazione IRCCS Istituto Nazionale Tumori, Milan, Italy.
authors: Claudia
authors: C
authors: Sangalli
authors: Department of Diagnostic Pathology, General Hospital, Treviso, Italy.
authors: Angelo Paolo
authors: AP
authors: Dei Tos
authors: Humanitas Cancer Center, Milan, Italy.
authors: Andrea
authors: A
authors: Marrari
authors: Adult Mesenchymal Tumour & Rare Cancer Medical Oncology Unit, Cancer Medicine Department, Fondazione IRCCS Istituto Nazionale Tumori, via G. Venezian, 1, 20133 Milan, Italy.
authors: Paolo G
authors: PG
authors: Casali
authors: Adult Mesenchymal Tumour & Rare Cancer Medical Oncology Unit, Cancer Medicine Department, Fondazione IRCCS Istituto Nazionale Tumori, via G. Venezian, 1, 20133 Milan, Italy.
authors: Silvia
authors: S
authors: Stacchiotti
keywords: Bone; Hemangiopericytoma; Metastasis; Prognosis; Sarcoma; Solitary fibrous tumour