[Abstract] BACKGROUND AND PURPOSE: Epithelioid sarcoma is a rare soft tissue sarcoma of unclear histologic origin. It has a unique biological behavior and is prone to local recurrence, lymph node spread, and/or distant metastasis. The aim of this study was to investigate the clinical features, diagnosis, treatment and prognosis of Epithelioid samoma (ES). METHODS: The clinical data of 14 cases of epithelioid sarcoma admitted to our hospital between January 1990 and December 2005 were retrospectively analyzed, and survival analysis was performed with follow-up data. All 14 cases in the group were treated surgically. The first surgery was performed in an outside hospital. One case was reoperated in our hospital (9 cases underwent extended resection and 2 cases underwent amputation; 4 cases underwent regional lymph node dissection at the same time), and 3 cases still underwent local resection or extended resection in an outside hospital. Nine cases received adjuvant treatment after surgery, including radiotherapy alone in 6 cases and radiotherapy + chemotherapy in 3 cases. Results: The whole group was diagnosed as epithelioid sarcoma in the pathology department of our hospital. 12 cases (85.7%) had local recurrence of tumor, 4 cases (28.6%) were found to have regional lymph node metastasis, and 9 cases died within 3 years after surgery. The overall 1?2 5 10-year survival rates for the whole group were 71.43%, 55.56%, 27.78% and 13.89%. Conclusion: Epithelioid sarcoma is not very malignant, but has a high local recurrence rate, is prone to lymph node and/or distant metastasis, and has a poor prognosis. Extensive resection or radical resection combined with prophylactic regional lymph node dissection is an effective treatment for epithelioid sarcoma. Keywords: epithelioid sarcoma: treatment: prognosis CFL: R738.6 Document ID: A Article ID: 1000-467X(2007)07-0782-03 Epithelioid sarcoma (ES) is a rare soft tissue tumor of unknown histological origin. Epithelioid sarcoma is a rare soft tissue tumor of unknown origin. Since it was first described and named by Enzinger [1] in 1970, there have been few reports from home and abroad, and most of them are case reports. This tumor is not very malignant. However, it tends to grow infiltratively along the tissue interstices and has a variety of clinical manifestations. The incidence of local recurrence and distant metastasis is high and the prognosis is not good, which should be taken seriously by clinicians. A total of 14 cases of epithelioid sarcoma were admitted to the Cancer Hospital of Chinese Academy of Medical Sciences from January 1990 to December 2005, and are analyzed and reported as follows. 1. Data and methods 1.1 General data The 14 patients in this group, 10 males and 4 females. The age of onset ranged from 26 to 57 years old, with a median age of 35 years old. The tumor occurred in the upper extremity in 6 cases. Among them, 3 cases were in the hand, 2 cases were in the forearm and 1 case was in the shoulder; 3 cases were in the lower limb, including 2 cases in the thigh and 1 case in the buttock; 3 cases were in the top of the head; 2 cases were in the perineum. The tumor diameter at the time of the first operation ranged from 2 to 7 cm, with an average of 3.8 cm. The time from the discovery of the mass to the consultation ranged from a few days to 3 years, with an average of 11 months. 1.2 Treatment All 14 cases in the group received surgical treatment. The first surgery was performed in an outside hospital. All 13 cases underwent only partial resection, except for one case with an extended resection. Three cases were reoperated in an outside hospital (one case underwent an extended resection and two cases underwent local resection after recurrence); 11 cases were operated in our hospital (three cases underwent an extended resection and eight cases were operated in our hospital after recurrence). Nine cases underwent extended resection, two cases underwent amputation, and four cases underwent prophylactic regional lymph node dissection. After surgery, 9 cases received adjuvant treatment, including radiotherapy alone in 6 cases and radiotherapy + chemotherapy in 3 cases. The dose of radiotherapy ranged from 40 to 70 Gy, with a mean of 59 Gy. 3-9 cycles of chemotherapy (adriamycin, cyclophosphamide, vincristine, etc.) were administered. 1.3 Pathological examination The first external pathological sections of all cases were re-reviewed in our hospital for diagnosis, and immunohistochemical staining for vimentin, AEl/AE3, CK, S.100, HMB-45, etc. was added. The pathological examination and immunohistochemical examination were repeated after surgery in our hospital, and the whole batch of pathological sections were reviewed and examined in this study. 1.4 Follow-up and statistical analysis Follow-up was performed by outpatient review, telephone or letter, etc. The follow-up deadline was September 31, 2006. All 14 cases in the group were followed up, and the follow-up rate was 100%. The follow-up period ranged from 7 to 144 months (median 26 months). Statistical analysis was performed using SPSS 13.0 statistical software and the Kaplan-Meier method was applied to analyze the survival rate. 2. Results 2.1 Pathological results There were 9 cases in the whole group with wrong or unclear pathological diagnosis after the first surgery in the hospital, and the misdiagnosis rate was 64.3%. Among them, 3 cases were diagnosed as smooth muscle sarcoma, 2 cases of synovial sarcoma, 1 case of malignant fibrous histiocytoma, 1 case of non-small cell sarcoma, and 2 cases could not be determined. The diagnosis of epithelioid sarcoma was confirmed in only 5 cases (35.7%) by external pathological examination of the first surgical specimen. 3 cases of metastatic lymph nodes were found in the 4 specimens with prophylactic regional lymph node dissection. Immunohistochemical examination: 14 cases were stained with vimentin and AE 1/AE3, all of which were positive; 12 cases were stained with s.100, all of which were negative except for one suspicious case; 8 cases were stained with CK, all of which were positive; 8 cases were stained with HMB.45, all of which were negative. All 14 cases were diagnosed as epithelioid sarcoma after pathological re-examination in our hospital. 2.2 Recurrence and lymph node metastasis 12 cases (85.7%) had local recurrence of tumor. Among them, 7 cases recurred for 2 times and 5 cases recurred for 1 time. The interval of recurrence ranged from 1 month to 61 months, with an average of 10 months. 4 cases (28.6%) were found to have regional lymph node metastasis. 2.3 Follow-up results The overall survival rates of the whole group at 1, 2, 5 and 10 years were 71.43%, 55.56%, 27.78% and 13.89% (see Figure 1). The median survival time was 32 months. 9 cases died within 3 years after surgery. The origin of epithelioid sarcoma is not clear, and it is still classified as a soft tissue tumor of unknown origin. However, most scholars now believe that it may originate from a primitive interrogative lobe cell with multidirectional differentiation potential, and thus can differentiate both to epithelial cells and to sarcoma cells [2]. Immunohistochemical staining of our cases suggested that cytokeratin (AEl/AE3, CK) was positive and vimentin was also positive, supporting the above view. Epithelioid sarcoma occurs in young adults and is more common in males. The tumors are mostly located in the extremities, especially in the distal segments of the upper extremities [3]. Most of them are solitary, and a few can be multiple. The initial clinical symptoms are mainly superficial subcutaneous or deep paratendinous hard nodes with unclear borders, which are mostly painless. The tumor is easy to infiltrate and grow or metastasize along the basket membrane, tendons, nerves, blood vessels, lymphatic vessels and so on to the surrounding area. Superficial tumor can gradually involve the skin and make the skin turn reddish-brown. In advanced stage, the tumor bulges the skin with central necrosis and often forms ulcer, erosion and bleeding. Therefore, two typical gross manifestations with large differences are often seen clinically: local skin elevation, erosion and necrosis, ulcer formation, diffuse tumor growth, mostly with hemorrhagic exudation, which can be secondary to infection, and unclear tumor border and morphology. Deep paratendinous hard nodules or masses with indistinct boundaries and poor mobility, with off-white or brownish-red cut surface. The local recurrence rate of epithelioid sarcoma is high, up to 77% in the literature, and Chase et al. reported a recurrence rate of up to 20% even after amputation. This may be related to the biology of epithelioid sarcoma, which is prone to infiltrative growth along the tissue spaces. In our group, local recurrence occurred in 12 patients, with a recurrence rate of 85.7%. Unlike other soft tissue sarcomas, the incidence of lymph node metastasis in epithelioid sarcoma is higher, with the rate of lymph node metastasis reported in the literature to be 22%-45%, and lymph node metastasis often occurs in the early stage of disease development. In our group, regional lymph node metastasis was found in 4 cases (28.6%). Moreover, among the 4 patients who underwent prophylactic lymph node dissection without local lymph node enlargement on preoperative examination, metastatic lymph nodes were found in 3 cases (75%). Preoperative diagnosis of epithelioid sarcoma is difficult. There is no specific presentation on imaging. The final diagnosis depends on pathological examination. However, because of the rarity of the tumor and the specific histomorphology, the diagnosis of epithelioid sarcoma is misdiagnosed by light microscopy alone. The misdiagnosis rate is high with light microscopy alone. In the literature, it is often misdiagnosed as benign granulosa cell tumor, squamous cell carcinoma, anaplastic malignant melanoma, clear cell sarcoma and synovial sarcoma. In our group, there were 9 cases with wrong or unclear pathological diagnosis after the first surgery, and the misdiagnosis rate was 64.3%. Immunohistochemical examination can help to clarify the diagnosis and differential diagnosis. We suggest that two groups of immunohistochemical staining, vimentin and AEl/AE3 or CK, are routinely used to help the diagnosis. The key to the treatment of epithelioid sarcoma is early diagnosis and extensive resection or radical resection as soon as possible, with prophylactic regional lymph node dissection recommended [7]. Local excision alone or simple extended resection does not seem to be adequate for epithelioid sarcoma. This is because the rate of local recurrence after such procedures is extremely high. Probably due to the aggressive nature of this tumor, it is difficult to determine the boundaries of the tumor with the naked eye, and the tumor often encircles important tissues such as tendons, nerves, and blood vessels, the scope of surgery is often inadequate for the surgeon to preserve function, making it difficult to truly remove the tumor completely. Most of the local resections and even some of the so-called extended resections are actually intratumoral resections of the tumor. The incidence of regional lymph node metastasis in epithelioid sarcoma is high, and prophylactic regional lymph node dissection may help to improve survival? In our group, prophylactic lymph node dissection was performed in 4 cases, and lymph node metastasis was found in 3 cases (75%). However, the role and significance of prophylactic regional lymph node dissection remains to be further studied in a large number of cases. For the need of postoperative adjuvant radiotherapy and chemotherapy. Most scholars currently believe that it is of little significance in controlling the effects of local recurrence and distant metastases. However, Callister et al. suggested that postoperative radiotherapy could help to improve the prognosis in patients who underwent conservative surgery or had less than 5 cm of resection.