Solitary fibrous tumors in the extremities: imaging findings for six patients

Abstract

The purpose of this study was to describe the magnetic resonance imaging (MRI) and computed tomography (CT) findings for solitary fibrous tumors (SFTs) in the extremities in correlation with histopathological findings. Between 2006 and 2013, 6 consecutive patients with SFT in an extremity were studied with MRI (6 patients) and CT (4 patients). Diffusion-weighted images were also performed in 3 patients and dynamic contrast-enhanced CT in 2 patients. All 6 tumors were diagnosed after surgical excision, and the pre-surgical imaging findings were correlated with the histopathological findings. As a result, all 6 patients were female, and each had a clearly palpable, well-circumscribed, round or oval mass adjacent to fascia in an extremity, of less than 10 cm maximum diameter in 5 patients. On MRI, the tumors were iso-intense with muscle on T1-weighted image, and appeared heterogeneous and high-intensity on T2-weighted image. After injection of a contrast agent, the tumors demonstrated strong enhancement. A vascular pedicle was detected in 4 patients with tumors having a maximum diameter more than 5 cm. Diffusion-weighted images demonstrated high signal intensities, and apparent diffusion coefficient values were iso to high compared to muscle (from 1.41-2.10×10(-3) mm(2)/s). All the tumors were benign histopathologically and clinically. In 1 patient, the imaging appearance revealed underlying histopathological components, including fibrous-rich, cellular-rich, and myxoid change areas. In conclusion, a SFT in an extremity comprises a well-circumscribed mass adjacent to fascia having a fibrous-dominant area, strong contrast enhancement, and a vascular pedicle.

Keywords: computed tomography; diffusion-weighted image; extremity; magnetic resonance imaging; solitary fibrous tumor.

Fig. 1

A 78-year-old woman with a palpable and painful mass in the right shoulder. a Sagittal T2-weighted image demonstrates a low- to high-intensity, well-circumscribed, lobulated mass compressing the triceps brachii and deltoid muscles. A flow void was detected in the mass. b Coronal oblique CT (arterial phase) demonstrates a vascular pedicle (white arrow) and numerous tumor vessels. c, d Comparing the axial T2-weighted image and histopathology demonstrates that the fibrous area corresponds to the area iso-intense to muscle. e, f Comparing the axial T2-weighted image and histopathology demonstrates that the cellular area corresponds to the moderate to high signal area. g, h Comparing the axial T1 fat-saturated post-gadolinium MR image and histopathology demonstrates that the area of myxoid change corresponds to the area without gadolinium enhancement (g; white arrow). Hematoxylin and eosin stains, 100× magnification.

Fig. 1

A 78-year-old woman with a palpable and painful mass in the right shoulder. a Sagittal T2-weighted image demonstrates a low- to high-intensity, well-circumscribed, lobulated mass compressing the triceps brachii and deltoid muscles. A flow void was detected in the mass. b Coronal oblique CT (arterial phase) demonstrates a vascular pedicle (white arrow) and numerous tumor vessels. c, d Comparing the axial T2-weighted image and histopathology demonstrates that the fibrous area corresponds to the area iso-intense to muscle. e, f Comparing the axial T2-weighted image and histopathology demonstrates that the cellular area corresponds to the moderate to high signal area. g, h Comparing the axial T1 fat-saturated post-gadolinium MR image and histopathology demonstrates that the area of myxoid change corresponds to the area without gadolinium enhancement (g; white arrow). Hematoxylin and eosin stains, 100× magnification.

Fig. 2

A 36-year-old woman with a palpable mass in the right thigh. a Coronal oblique CT (arterial phase) demonstrates a well-circumscribed, markedly enhancing mass between the medial great and sartorius muscles. A vascular pedicle is visible (white arrow). b Coronal T1 fat-saturated post-gadolinium MR image demonstrates strong enhancement, but contains a reticular, low-enhancing area. A biopsy scar is visible outside the tumor (white arrow). c The apparent diffusion coefficient (ADC) map demonstrates a heterogeneous, high value, with a mean of 2.10×10^–3 mm² / second.

Fig. 3

A 43-year-old woman with a palpable and painful mass in the right thigh. a An axial T2-weighted image demonstrates a low- to high-intensity, well-circumscribed, oval mass compressing the medial great, sartorius and adductor longus muscles. A biopsy scar is visible inside the tumor (white arrow). b The apparent diffusion coefficient (ADC) map demonstrates a value similar to muscle, with a mean of 1.41×10^–3 mm² / second.

Fig. 4

A 47-year-old woman with a palpable mass in the left thigh. a An axial T1-weighted image demonstrates an iso-intense, well-circumscribed, oval mass within the subcutaneous tissues adjacent to the medial great and gracilis muscles (white arrow). b An axial T2-weighted image demonstrates the markedly high intensity of this lesion. c The apparent diffusion coefficient (ADC) map demonstrates a homogeneous, high value compared to muscle, with a mean of 1.96×10^–3 mm² / second.

Fig. 5

A 13-year-old female with a palpable mass in the left upper arm. a An axial T2-weighted image demonstrates an iso- to moderate-intensity, well-circumscribed, round mass within the subcutaneous tissues adjacent to the triceps brachii muscle. b Coronal T1 fat-saturated post-gadolinium MR image demonstrates the strong enhancement of this lesion. A biopsy scar is visible outside the tumor (white arrow).

Fig. 6

A 43-year-old woman with a palpable mass in the left shoulder. a An axial T2-weighted image demonstrates a heterogeneous, high-intensity, well-circumscribed, oval mass within the subcutaneous tissues adjacent to the deltoid and triceps brachii muscles. b Coronal T1 fat-saturated post-gadolinium MR image demonstrates strong enhancement and a small vascular pedicle (white arrow).