Soft tissue clear cell sarcoma:a clinicopathological analysis of fifteen cases
LI Weiling
FU Chunling
JIANG Qingming
ZENG Zhen
LI Guangxin
LI Wen
XIONG Jianbo
XIAO Lidan
Abstract：Objective To investigate the clinicopathological features and differential diagnosis of soft tissue clear cell sarcoma(CCS).Methods The clinicopathological data of 15 cases of soft tissue clear cell sarcoma diagnosed at the Department of Pathology,Chongqing University Cancer Hospital and Beibei Traditional Chinese Medical Hospital of Chongqing from 2018 to 2022 were collected.Their pathological characteristics,immunophenotypes and differential diagnosis were analyzed by using immunohistochemical EnVision staining(antibodies included S-100,SOX10,HMB-45,MelanA,etc.)and fluorescence in situ hybridization for detection of the EWSR1-ATF1 fusion gene and EWSR1 gene breakage.Results The average age of the 15 patients with soft tissue clear cell sarcoma was 42 years,with a male-to-female ratio of 7∶8.The tumor was prone to occur in the limbs,especially the foot and ankle,followed by the knee,wrist,armpit,and chest wall.Involvement of other organs was rare.Among the 15 cases,3 cases were located in the plantar region,1 case in the dorsal foot,2 cases in the ankle joint,2 cases in the popliteal fossa,1 case in the thigh,1 case in the thumb,1 case in the palm,3 cases in the axilla and chest wall,and 1 case in the left neck and shoulder.Among them,2 patients had a history of trauma at the lesion site.All 15 patients underwent tumor resection,among whom 2 patients alao underwent amputation,2 patients experienced local recurrence with regional lymph node metastasis within 1 month after surgery,1 patient developed metastases to the brain,bone,pancreas,lung and abdominal lymph nodes 9 months postoperatively,and 1 patient had recurrence with lung metastasis 17 years after surgery.Microscopically,the tumor was mainly composed of spindle-shaped,round,or oval cells with abundant cytoplasm.It was closely associated with surrounding tendons or aponeuroses through a small amount of fibrous connective tissue.The tumor cells were round,oval,or polygonal,with clear or weakly eosinophilic cytoplasm.Some nuclei were slightly plasmacytoid,with prominent eosinophilic macronucleoli.Mitotic figures ranged from 0 to 23 per 10 high-power fields(HPF),and in most cases,the mitotic figures in hot spot areas were 6-8/10HPF.Immunophenotypically,tumor cells expressed Vimentin(15/15),Sox10(15/15),S-100(15/15),HMB45(14/15),and MelanA(14/15).The percentage of Ki-67-positive tumor cells ranged from 3％to 50％.FISH was performed in all 15 cases:10 cases showed EWSR1 gene breakage,4 cases had EWSR1-ATF1 fusion mutations,and 1 case(detected by next-generation sequencing)had an EWSR1(7)-CREB1(7)fusion mutation.Among the 15 cases,12 cases obtained follow-up data,with a follow-up period of 20-231 months(mean,40 months).Conclusion Soft tissue clear cell sarcoma has a high rate of missed diagnosis and misdiagnosis in preoperative puncture biopsy,and it is very easy to be misdiagnosed as malignant melanoma and other soft tissue malignant tumors.However,it harbors the unique EWSR1-ATF1 fusion gene,and mastering its pathological characteristics is very important for diagnosis and treatment.
Keywords：Soft tissue clear cell sarcomaEWSR1 geneDiagnosisDifferential diagnosis
Publication Date：2025-09-28
Online Publishing Date：2025-11-13(First online date of this platform, not the publication date of the document)
Pages：7( 1124-1130 )