Solitary fibrous tumor is a spindle cell tumor first described in the pleura, but also found in multiple extrathoracic sites including the meninges, orbit, nasal and paranasal sinuses.

Localization

 pleural solitary fibrous tumor (pleural SFT)
 extrapleural solitary fibrous tumor

• cavernous sinus (#12808569#)
• cerebellopontine angle (#14707876#)
• kidney (#11866209#)
• oral cavity

Synopsis

 possible glomus tumor-like foci

Immunohistochemistry

 vimentin +
 CD34 +
 BCL2 +
 CD99 +

 +/- Factor XIIIa
 +/- alpha-smooth muscle actin were less commonly reactive

 S-100-
 desmin-
 CD31-
 CD68-

Ultrastructure (#15909170#)

 perivascular undifferentiated cells
 pericytes
 endothelial cells
 glomoid foci of myopericytes
 Weibel-Palade bodies in capillary endothelium
 single and clustered endothelial cells with intracytoplasmic lumen

Histogenesis

 SFT may originate from a unique, perivascular multipotent mesenchyme sharing with its lineage with pericytes, fibroblasts, and infrequently, endothelium. Consequently, morphological features of SFT may become diversely varied by whether predominantly constituent cells are undifferentiated, pericytic or fibroblastic in nature. (#15909170#)

Variants

 salivary gland heterotopia (#14707876#)

Immunochemistry

 CD34+
 factor XIIIa F13a+
 CD99+
 BCL2+

Associations

 type I neurofibromatosis (NF1) (#15013617#)

Cytogenetics

 4q13 rearrangements

See also

 SFT spectrum (solitary fibrous tumor-hemangiopericytoma spectrum)

References

 Gengler C, Guillou L. Solitary fibrous tumour and haemangiopericytoma: evolution of a concept. Histopathology. 2006 Jan;48(1):63-74. PMID: #16359538#