Intracranial Solitary Fibrous Tumor with Pseudopapillary Architecture: An Uncommon Tumor with Unusual Histopathology

Abstract

Solitary fibrous tumor (SFT) is an uncommon soft tissue neoplasm first described in the pleura in 1931 and later recognized in other anatomical locations. Involvement of the central nervous system is rare; there are approximately 250 cases of central nervous system SFTs in the English literature. To the best of our knowledge, this is the first report of an intracranial SFT showing pseudopapillary architecture. The patient was a 73-year-old male who presented with recent onset altered mental status. Imaging studies showed a large left posterior parieto-occipital region intradural extra-axial mass with significant mass effect in the adjacent brain. Neuropathologic examination demonstrated a spindled mesenchymal neoplasm with variable cellularity and prominent collagen deposition. In areas, the tumor was discohesive, imparting a prominent pseudopapillary architecture. Entrapped brain parenchyma was present, indicating brain infiltration. The tumor cells were positive for CD34, CD99, vimentin, BCL-2, and STAT6; EMA was negative. Both the Ki-67 and mitotic indices were low, and anaplastic nuclear features were absent. To the best of our knowledge, this is the first example of an intracranial SFT with pseudopapillary architecture. Occasional extracranial SFTs showing papillary features have been reported. The significance of this architectural pattern is unclear and may be elucidated by future studies.

[N A J Med Sci. 2016;9(4):181-186.   DOI:  10.7156/najms.2016.0904181]

Key Words: solitary fibrous tumor, central nervous system, intracranial, pseudopapillary