[1287] Solitary Fibrous Tumor of Head and Neck; a Diverse Clinicopathologic Spectrum

Daniel Kleven, Rafik Abdelsayed, Suash Sharma. Medical College of Georgia, Georgia Health Sciences University, Augusta, GA; College of Dental Medicine, Georgia Health Sciences University, Augusta, GA

Background: Solitary fibrous tumors (SFT) are typically benign, circumscribed mesenchymal tumors of CD34-positive fibroblastic lineage with prominent hemangiopericytoma-like branching vascular pattern, occurring mostly in middle-aged adults. These are very rare in head and neck region, and malignant examples are exceptional.
Design: We identified 9 cases of SFT of the head and neck from the pathology archives and studied their clinicopathologic characteristics. IHC for CD34, vimentin, S100, BCL2, SMA, desmin, keratins, CD68, EMA, GFAP, neurofilament, synaptophysin, and ki67 were performed. Primary meningeal hemangiopericytoma, synovial sarcoma, fibrosarcoma, and sinonasal glomangiopericytoma were excluded. Other lesions excluded especially in mucosal sites were neurofibroma, schwannoma, leiomyoma, and spindle cell myoepithelioma.
Results: The age range was 28 to 83 years (mean 54); 8 were males and one female. Two were intracranial (pons, frontal meningeal), 4 soft tissue (nasopharynx, parapharyngeal, inferior orbital, parotid), and 3 oral tumors (2 buccal mucosa, 1 floor of mouth). Histologic examination showed a spindle cell neoplasm with alternating hypo- and hypercellular areas, with intervening ropy collagen, patchy branching vascular pattern, diffuse CD34 and significant BCL2 positivity. Malignant cases exhibited significant pleomorphism, foci of necrosis, and mitotic activity of more than 4 per 10 high-power fields (up to 23). Ki67 labeling index in malignant SFT varied from 5 to 25 percent. One case in parapharyngeal region appeared to arise from a benign / low-grade SFT by dedifferentiation. Two cases recurred after 24 (pons) and 7 (parotid) years. There was no evidence of metastasis.
Conclusions: SFT of head and neck can occur in diverse locations, are mostly benign, non-recurring tumors with characteristic histology and diffuse CD34 positivity that can involve meninges, mucosal sites (oral, respiratory), skull base, parotid or soft tissue. Malignant examples, may occur de novo or by dedifferentiation, show overt anaplasia, increased mitotic activity, and can develop late recurrences.
Category: Head & Neck

Tuesday, March 5, 2013 9:30 AM

Poster Session III # 158, Tuesday Morning

 

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