(A) Prior to radiation therapy

(A) Prior to radiation therapy. bone (n = 4), and liver (n = 3). There was a mean lag time of 14. 2 years between the diagnosis of the initial meningeal tumor to that of systemic metastasis. The median age at initial tumor onset was 37. 1 years in the metastatic group and 52. 5 in the non-metastatic group. The 10-year survival rates of the metastatic- and non-metastatic groups were 100% and 33%, respectively. A-1165442 The significant prognostic factors for poor outcomes on univariate analysis included advanced age (45 years) and large initial tumor size (5 cm). In contrast, the patients with higher tumor grade, high mitotic rate (5/10 high-power fields), high Ki-67 index (5%), and the presence of necrosis or CD34 positivity showed tendency of poor prognosis but these parameters were not statistically significant poor prognostic markers. == Conclusions: == Among patients with SFTs, younger patients ( <45 years) experienced longer survival times and paradoxically had more frequent extracranial metastases after long latent periods than did older patients. Therefore , young patients with SFTs require careful surveillance and follow-up for early detection of systemic metastases. Keywords: Central nervous system, Hemangiopericytoma, Neoplasm metastases, NAB2-STAT6 gene fusion, Solitary fibrous tumors Solitary fibrous A-1165442 tumors (SFTs), first described in 1931 by Klemperer and Coleman [1], are rare spindle-cell mesenchymal tumors that often arise in the pleural cavity. However , SFTs can arise in the extrapleural sites such as thoracic wall, mediastinum, pericardium, retroperitoneum, and abdominal cavity. They can also occur in the subcutaneous and deep soft tissues of the extremities and extracompartmentally in the head and neck [1, 2]. More than 100 cases of intracranial SFTs have been reported to date. A-1165442 However , the exact incidence of intracranial SFTs is unknown. The current consensus is that extracranial hemangiopericytomas (HPCs) and SFTs are synonymous. Such tumors should be called SFTs (rather than HPCs), because HPCs do not originate from or differentiate into pericytes [2]. The prototypical pericytic neoplasms are myopericytomas and sinonasal HPCs [2]. However , in the central nervous system (CNS), HPCs and SFTs exhibit distinct biological behavior, and are therefore considered separate entities. For instance, intracranial HPCs tend to be aggressive, while intracranial SFTs are typically relatively benign [3]. Recently, NAB2-STAT6 gene fusions have been identified using whole-exome sequencing in intracranial and extracranial soft tissue HPCs and SFTs [4]. Therefore , the use of a single, unifying term to describe intracranial SFTs is preferred than HPCs with the HPC morphology implies a cellular and aggressive variant, and SFT morphology a fibrous and benign variant of the same disease [5]. Meningeal HPCs commonly occur around the same age as do meningiomas (range, 26 to 73 years; mean, 48 years). However , compared to meningiomas, HPCs are more common in men than in women [6]. According to Pistolesiet al. s report [7], the mean time to the first local recurrence and to the appearance of extraneural metastases of meningeal HPCs were 3. 9 years and 8. 3 years, respectively. The 10-year survival rate was 83. 9% [6]. This study was designed to clarify the clinicopathological characteristics of metastatic and non-metastatic meningeal SFTs. We analyzed meningeal SFTs (cellular variant) displaying extracranial dissemination, and compared them with non-metastatic meningeal SFTs. Patients with metastatic meningeal SFTs (metastatic group) were significantly younger than were those with non-metastatic tumors (non-metastatic group). Interestingly, the metastatic group exhibited better long-term survival than did the non-metastatic group. == MATERIALS AND METHODS == All cases of meningeal SFTs/HPCs between January 1995 and January 2013 were retrieved from the pathology archives at the Seoul National University Hospital (SNUH). We selected cases that matched the search term solitary fibrous tumor or hemangiopericytoma, and 48 cases of meningeal HPCs/SFTs were selected from this 18-year period. There was no sex predominance. The mean patient age was 48. 1 years (range, 21 to 77 years). We selected 19 cases of pathologically and STAT6 immunohistochemically confirmed meningeal SFTs that were followed up for more than 11 years. Ten cases presented with systematic extracranial metastases (metastatic group), while nine had no extracranial metastases (non-metastatic group). The medical and pathological records of the19 cases are summarized inTable 1 . == Table 1 . == Summary of the patients with and without meningeal SFT/HPC and extracranial metastasis, treated in Seoul National University Hospital (SNUH) SFT, solitary fibrous tumor; HPC, hemangiopericytoma; Tx, therapy; F, CDKN1B female; HPC, hemangiopericytoma; GTR, gross total resection; RT, radiotherapy; DBD, death by disease; Rt., right; L/E, lower extremity; CT, chemotherapy; VIP, VP-16, ifosfamide, cisplatin; Lt., left; GKS, gamma knife surgery; M, male; STR, subtotal resection; EAC, external auditory canal; CPA, cerebellopontine angle; T-P-O, temporoparietooccipital lobe; SFT, solitary fibrous tumor; F-T, frontotemporal; NA, not applicable. Two pathologists (N. H and S. -H. P) performed all of the pathological reviews. A Ventana autostainer was used for immunohistochemical staining, according to the.