Primary giant cell tumors of soft tissue

Characteristics of primary giant cell tumor in soft tissue on magnetic resonance imaging: A case report

BACKGROUND

Primary soft tissue giant cell tumor (GCT-ST) is rare and has relatively low malignant potential. Most reports are pathological and clinical studies, while imaging studies have only been reported in cases of adjacent bone or with atypical cystic degeneration. With regard to the findings on magnetic resonance imaging (MRI) or ultrasonography, superficial masses can be further identified based on facial edema, skin thickening, skin contact, internal hemorrhage or necrosis and lobulation of the mass. Unlike deep-seated masses, MRI features do not always provide an accurate diagnosis for benign and malignant patients with superficial soft-tissue lesions. Thus, the application of diffusion-weighted imaging (DWI) to evaluate superficial soft tissue tumors is necessary.

CASE SUMMARY

A 36-year-old woman who had a suspected malignant tumor in the upper limb on ultrasound and computed tomography is reported. The signal intensity of the suspected tumor was heterogeneous on plain MRI; nodular and heterogeneous enhancement was observed in the tumor with irregular shapes and blurred margins on dynamic contrast-enhanced MRI. The lesion on DWI was hyperintense with a higher mean apparent diffusion coefficient (ADC) value. Finally, a GCT-ST was confirmed by pathology. This case suggests that GCT-ST should be distinguished as a benign soft tissue mass from giant cell-rich soft tissue neoplasms or malignant tumors.

CONCLUSION

The MRI features of the superficial GCT-ST in the upper limb included heterogeneous signal intensity within the lesion on T2-weighted image (T2WI) and T1-weighted fat-saturation spoiled gradient recalled echo (T1 FSPGR), nodular enhancement with blurred margins, irregular shapes, and a slow-increased enhancement. DWI could be used to differentiate a benign soft tissue mass from a malignant mass by the mean ADC value and provide more radiologic-pathologic information for the diagnosis of GCT-ST. Comprehensive imaging of primary GCT-ST could help complete tumor resection, and in turn likely prolong survival after surgery.

Immunohistochemical detection of GLUT-1 can discriminate between reactive mesothelium and malignant mesothelioma

The separation of benign reactive mesothelium (RM) from malignant mesothelial proliferation can be a major challenge. A number of markers have been proposed, including epithelial membrane antigen, p53 protein, and P-glycoprotein. To date, however, no immunohistochemical marker that allows unequivocal discrimination of RM from malignant pleural mesothelioma (MPM) has been available. A family of glucose transporter isoforms (GLUT), of which GLUT-1 is a member, facilitate the entry of glucose into cells. GLUT-1 is largely undetectable by immunohistochemistry in normal epithelial tissues and benign tumors, but is expressed in a variety of malignancies. Thus, the expression of GLUT-1 appears to be a potential marker of malignant transformation. Recently, in fact, some studies have shown that GLUT-1 expression is useful for distinguishing benign from malignant lesions. The purpose of the present study was to evaluate the diagnostic utility of GLUT-1 expression for diagnostic differentiation between RM and MPM. Immunohistochemical staining for GLUT-1 was performed in 40 cases of RM, 48 cases of MPM, and 58 cases of lung carcinoma. Immunohistochemical GLUT-1 expression was seen in 40 of 40 (100%) MPMs, and in all cases the expression was demonstrated by linear plasma membrane staining, sometimes with cytoplasmic staining in addition. GLUT-1 expression was also observed in 56 out of 58 (96.5%) lung carcinomas. On the other hand, no RM cases were positive for GLUT-1. GLUT-1 is a sensitive and specific immunohistochemical marker enabling differential diagnosis of RM from MPM, whereas it cannot discriminate MPM from lung carcinoma.