Case ReportCentral Nervous System Solitary Fibrous Tumor/Hemangiopericytoma Penetrating the Skull Bone: An Unusual Presentation
Introduction
Solitary fibrous tumor/hemangiopericytoma (SFT/HPC) is a rare soft tissue neoplasm that can demonstrate both benign and malignant behavior. It has typically been found in 3 areas: the pleura, meninges and extrathoracic soft tissues.1 During the past decade, SFT and HPC were classified as separate disease entities. After recent developments in molecular biology, however, both are now considered as morphological variants of the same lesion.2, 3, 4
Central nervous system (CNS) SFT/HPC only comprises <1% of all intracranial tumors and 1.6%–4% of all dura-related tumors.1,3,5 Only small case series and a few systemic reviews have been reported owing to its rarity. Thus, providing a proper evaluation and diagnosis can be challenging.5 Moreover, the presenting symptoms can vary, although most will be neurologic, depending on the localization of the tumor, because it will usually grow along the sinuses.1,5,6
We have presented an unusual case of CNS SFT/HPC that had penetrated the full thickness of the skull bone and externalized, rather than invading intracranially, resulting in the initial misdiagnosis as a subcutaneous mass.
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Case Description
A 64-year-old woman had visited our institution for the evaluation of a forehead mass (Figure 1A). She had undergone pancreatectomy and splenectomy to treat pancreatic cancer 12 years previously. The cancer was in complete remission and she had not undergone chemoradiotherapy. Otherwise, she did not have any medical history warranting an evaluation for a head and neck tumor. The mass measured 2 cm in diameter and was soft, immobile, and nontender. It did not show pulsation or enlargement on
Discussion
CNS SFT/HPC is a rare mesenchymal tumor, and its precise classification and terminology have been only recently established. Although SFT and HPC were previously distinguished as 2 separate entities, the current classification has evolved to encompass the 2 as an overlapping or identical entity, because both share inversions at 12q13 and fusions of the NAB2 and STAT6 genes.2,4 The 2016 World Health Organization classification of CNS tumors restructured the 2 distinct entities into SFT/HPC and
Conclusions
The treatment of CNS SFT/HPC can be challenging because it will infiltrate aggressively and recurrence and distant metastasis frequently develop. If no neurologic symptoms have developed, the diagnosis can be delayed owing to its characteristic intracranial growth. Also, performance of gross total resection will be more difficult at an advanced tumor stage. However, as in the present case, direct extracranial extension is also possible. Complete resection will be feasible if the surgeon has
Acknowledgments
The authors would like to express sincere gratitude to Tae Jung Kim in the Department of Hospital Pathology, Yeouido St. Mary’s Hospital, College of Medicine, The Catholic University of Korea, for providing his consultation regarding the pathologic evaluation.
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Conflict of interest statement: The authors declare that the article content was composed in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.