Malignant Giant Cell Tumor of Soft Tissue: A Case Report of Intramuscular Malignant Giant Cell Carcinoma of the Tensor Fasciae Latae

INTRODUCTION: Giant cell tumor of soft tissue (GCT-ST)is a low-grade ST tumor that occurs most frequently below the skin and sometimes, extending deeper into the tissues. The tumor is usually hard, painless and considered rare in ST. CASE REPORT: We report a rare case of a middle-aged woman that presented with a tumor arising from the right tensor fasciae latae muscle. The patient initially opted for traditional Chinese herbal treatment, which we believe, aggravated the growth of the tumor. Radiographic imaging showed clear tumor margins. The histopathological biopsy of the lesion located in the tensor fasciae latae muscle showed a mixture of mononucleated and multinuclear giant cells composed of mesenchyme spindle-shaped cells positive for CD34 and CD88. The patient was treated through surgical resection of the tumor and scheduled for close follow-up. CONCLUSION: Since GCT-ST is rare, they are often initially misdiagnosed. These tumors have the tendency to increase in size exponentially within a short period of time, which is why clinical presentation and imaging are necessary for a better pre-operative diagnosis. Radical surgical excision or radiotherapy with close follow-up is recommended for all cases due to the high rate of reoccurrence.