Cellular solitary fibrous tumor in the mental area: a case report and literature review

Abstract

Solitary fibrous tumors (SFTs) are rare benign mesenchymal tumors that occur mainly in the pleura. We herein report the first case of a cellular SFT located in the mental region of the head and neck in a 46-year-old woman. Facial computed tomography revealed a mass measuring 0.8 cm with clear boundaries in the right mental region. After excision of the mass, expert pathologists diagnosed a cellular SFT. To our knowledge, this is the first case of a cellular SFT identified in the subcutaneous tissue of the mental region of the head and neck. Because the postsurgical prognosis of SFTs is unpredictable, long-term follow-up and further studies are necessary to determine the characteristics of cellular SFTs in the head and neck region.

Keywords: Head and neck neoplasms; STAT6 transcription factor; immunohistochemistry; mass excision; solitary fibrous tumors; subcutaneous tissue.

Figure 1.

Facial computed tomography revealing a mass measuring 0.8 cm with clear boundaries in the right mental region as shown in the (a) axial, (b) sagittal, and (c) coronal planes.

Figure 2.

Microscopic findings of the cellular solitary fibrous tumor. (a) The tumor specimen shows high cellularity with a well-demarcated boundary (hematoxylin–eosin staining; magnification, 10×). (b) The tumor is well circumscribed with a thin-walled capsule (hematoxylin–eosin staining; magnification, 100×). (c) The tumor is composed of bland, spindled-shaped cells in a “patternless pattern,” with variably intervening dense fibrous stroma and dilated and branching thin-walled staghorn-shaped vessels (hematoxylin–eosin staining; magnification, 200×).

Figure 3.

Immunohistochemical findings of the cellular solitary fibrous tumor. (a) The tumor cells are positive for vimentin (magnification, 200×). (b) The tumor cells show nuclear expression of signal transducer and activator of transcription-6 (STAT6) (200×). (c) Immunostaining for CD34 shows positive results (magnification, 200×). The tumor cells are negative for (d) S-100 and (e) transducin-like enhancer protein 1 (TLE1) (magnification, 200×). (f) The Ki67 labeling index is <2% (magnification, 200×).