A 69-year-old man presented at our hospital with a 5-month history of a rapidly enlarging mass in the right thigh. His past history was pulmonary tuberculosis treated with thoracoplasty and hepatitis C. Physical examination revealed the presence of a large irregular mass with multiple ulcers and necrotic tissues, measuring approximately 10 x 10 cm in the lateral side of the proximal thigh (Figure 1). Admission laboratory data showed high levels of LDH, GOT, GPT, and ALP, which are 643, 80, 39, and 441, respectively. Typical tumor markers were within normal limits. A roentgenogram of the right proximal thigh showed no apparent expansion to the femur. Chest roentgenogram and computed tomography showed no apparent metastatic lesion and no focus of pulmonary tuberculosis. MR images demonstrated relatively a well defined and heterogeneous mass, which was attached to the fascia lata and expanded across the skin layer (Figures 2(a), 2(b)). The signal intensity of the mass was isointense to the adjacent skeletal muscles on T1-weighted images and inhomogeneous hyperintense on T2-weighted images. The mass was relatively well defined and enhanced with Gd-DTPA on STIR sequences (Figure 2(c)). However, partial infiltrating expansions to subcutaneous tissues of the mass made its margins unclear. Despite the mass contacted with the compression to the tensor fascia lata muscle, the gluteus maximus muscle, and the gluteus medius muscle, no apparent signal intensity changes of muscles were seen. Thallium-201 scintigrams showed a robust accumulation accorded for the mass in both of early and delayed phases (Figure 3). No other abnormal accumulation was detected.
Based on clinical findings and imaging characteristics, the tumor was diagnosed as a primary soft tissue tumor and an incisional biopsy was performed. Histopathology of the permanent sections showed the nodular or sheets-like proliferation pattern of small round cells with a high nuclear/cytoplasmic ratio in the background of sparse extracellular collagen (Figure 4). Immunohistochemistry of the sections demonstrated that the staining of BCL2, MIC2, CD56, O-13, neuron specific enolase (NSE), and synaptophysin were positive. They were negative for HMB-45, S-100, broad cytokeratin (AE1/AE3 and MNF116), CD45, CD79a, CD3, and CD20. In addition, the RT-PCR showed the presence of EWS/FLI-1 fusion transcript from tumor specimens. Together with the results of several examinations, we diagnosed this tumor as EES.
Considering patient's age, hepatic dysfunction, and patient's disagreement with chemotherapy, we precluded the choice of the neoadjuvant chemotherapy. To define surgical margins especially at subcutaneous tissues and to increase tumor resectability, we determined to treat the patient with pre-operative low-dose RT and additional administration of sanazole before surgery. As a result of the total dose irradiation of 30 Gy in 15 fractions with sanazole (0.6 g/m2  x 10 days), the tumor volume was reduced to approximately 40% of the pre-treatment condition (Figure 5). On thallium-201 scintigrams, the accumulation of the tumor markedly decreased in both of early and delayed phases. Subsequently, we could perform the surgical resection with subtotal resection of the tensor fascia lata muscle, the gluteus maximus muscle, the gluteus medius muscle, and adjacent soft tissues to obtain wide surgical margins (Figure 6(a)). The huge surgical defect in the lateral thigh was repaired with a musculocutaneous flap of rectus abdominis (Figure 6(b)). There was no major complication in the perioperative period. Histological examination of the resected tissue demonstrated clear surgical margins. Because the tumor cells completely showed necrotic appearances and there were no viable tumor cells in the tumor specimen, we diagnosed the necrosis ratio as 100% (Figure 7). Based on the histological findings, we could confirm a high efficacy of pre-operative low-dose RT with sanazole in the present case. The patient underwent follow-up without any local recurrence or distant metastasis, and presented without any postoperative functional disturbance for 24 months after surgery.