Background and purpose:Human papilloma virus(HPV)infection status is crucial for diagnosing cervical precancerous lesions and classifying cervical cancer.High-risk(HR)HPV is often linked to P16 protein overexpression,so P16 detection via immunohistochemistry(IHC)is commonly used to assess HPV infection.However,the differences between HPV status and P16 expression remains unclear.An in-depth study of the correlation between HPV and P16 is essential for clinical guidance.Methods:We retrospectively collected clinical and pathological data of cervical lesions from 618 patients diagnosed at the Department of Pathology,Fudan University Shanghai Cancer Center from January 2020 to December 2023(Ethical number:050432-4-2307E).Polymerase chain reaction(PCR)reverse dot hybridization was used to detect HPV including HR and low-risk(LR)subtypes,and immunohistochemistry was used to detect P16 for comparative analysis.Based on different clinical and pathological diagnoses,the sensitivity and specificity of P16 expression in evaluating HPV infection were evaluated.Among the 618 cases of cervical lesions,there were 92 cases of cervical squamous cell carcinoma,257 cases of cervical adenocarcinoma,79 cases of high-grade squamous intraepithelial lesions(HSIL),105 cases of low-grade squamous intraepithelial lesions(LSIL),and 85 cases of chronic cervical inflammation.Results:According to clinical diagnosis,the HR-HPV positive rate in cervical squamous cell carcinoma was 88.0%(81/92),the P16 positive rate was 91.3%(84/92),and the overall consistency rate between P16 and HPV detection was 90.2%(88/92);for HR-HPV infection,the sensitivity and specificity of P16 were 96.3%and 45.5%.The positive rate of HR-HPV in adenocarcinoma was 54.5%(140/257),the positive rate of P16 was 58.8%(151/257),and the overall consistency rate between P16 and HPV detection was 82.5%(212/257);for HR-HPV infection,the sensitivity and specificity of P16 were 87.9%and 76.1%.In HSIL,the HR-HPV positive rate was 75.9%(60/79),the positive rate of P16 was 70.9%(56/79),and the overall consistency rate between P16 and HR-HPV detection was 82.2%(65/79);for HR-HPV infection,the sensitivity and specificity of P16 were 85.0%and 73.7%.In LSIL,the HR-HPV positive rate was 73.3%(77/105),the positive rate of P16 was 8.5%(9/105),and the overall consistency rate between P16 and HR-HPV detection was 33.3%(35/105);for HR-HPV infection,the sensitivity and specificity of P16 were 10.4%and 96.4%.In chronic cervical inflammation,the HR-HPV positive rate was 20%(17/85),the positive rate of P16 was 0.0%(0/85);for HR-HPV infection,the sensitivity and specificity of P16 were 0.0%and 100.0%.There was a significant positive correlation between P16 positivity and HPV16/18 in cervical squamous cell carcinoma,adenocarcinoma,and HSIL(P=0.000),while there was no significant correlation in LSIL and chronic cervical inflammation(P＞0.05).Conclusion:In cervical squamous cell carcinoma and adenocarcinoma,the consistency of P16 expression and HPV DNA positivity are high,especially in HPV16/18 subtype.There is a good concordance between HR-HPV positivity and P16 protein overexpression.The positive expression of P16 in HSIL may initially reflect HPV infection status.However,in LSIL and chronic cervicitis,P16 expression may not accurately correlate with HPV infection.The inconsistency between P16 and HPV DNA testing could be influenced by multiple factors,including HPV subtypes,histopathological categories,specimen quality,and technical limitations.In clinical practice,it is recommended to conduct comprehensive analysis or employ multiple diagnostic methods to confirm HPV infection status for precise evaluation.

Background and purpose:Human papilloma virus(HPV)infection status is crucial for diagnosing cervical precancerous lesions and classifying cervical cancer.High-risk(HR)HPV is often linked to P16 protein overexpression,so P16 detection via immunohistochemistry(IHC)is commonly used to assess HPV infection.However,the differences between HPV status and P16 expression remains unclear.An in-depth study of the correlation between HPV and P16 is essential for clinical guidance.Methods:We retrospectively collected clinical and pathological data of cervical lesions from 618 patients diagnosed at the Department of Pathology,Fudan University Shanghai Cancer Center from January 2020 to December 2023(Ethical number:050432-4-2307E).Polymerase chain reaction(PCR)reverse dot hybridization was used to detect HPV including HR and low-risk(LR)subtypes,and immunohistochemistry was used to detect P16 for comparative analysis.Based on different clinical and pathological diagnoses,the sensitivity and specificity of P16 expression in evaluating HPV infection were evaluated.Among the 618 cases of cervical lesions,there were 92 cases of cervical squamous cell carcinoma,257 cases of cervical adenocarcinoma,79 cases of high-grade squamous intraepithelial lesions(HSIL),105 cases of low-grade squamous intraepithelial lesions(LSIL),and 85 cases of chronic cervical inflammation.Results:According to clinical diagnosis,the HR-HPV positive rate in cervical squamous cell carcinoma was 88.0%(81/92),the P16 positive rate was 91.3%(84/92),and the overall consistency rate between P16 and HPV detection was 90.2%(88/92);for HR-HPV infection,the sensitivity and specificity of P16 were 96.3%and 45.5%.The positive rate of HR-HPV in adenocarcinoma was 54.5%(140/257),the positive rate of P16 was 58.8%(151/257),and the overall consistency rate between P16 and HPV detection was 82.5%(212/257);for HR-HPV infection,the sensitivity and specificity of P16 were 87.9%and 76.1%.In HSIL,the HR-HPV positive rate was 75.9%(60/79),the positive rate of P16 was 70.9%(56/79),and the overall consistency rate between P16 and HR-HPV detection was 82.2%(65/79);for HR-HPV infection,the sensitivity and specificity of P16 were 85.0%and 73.7%.In LSIL,the HR-HPV positive rate was 73.3%(77/105),the positive rate of P16 was 8.5%(9/105),and the overall consistency rate between P16 and HR-HPV detection was 33.3%(35/105);for HR-HPV infection,the sensitivity and specificity of P16 were 10.4%and 96.4%.In chronic cervical inflammation,the HR-HPV positive rate was 20%(17/85),the positive rate of P16 was 0.0%(0/85);for HR-HPV infection,the sensitivity and specificity of P16 were 0.0%and 100.0%.There was a significant positive correlation between P16 positivity and HPV16/18 in cervical squamous cell carcinoma,adenocarcinoma,and HSIL(P=0.000),while there was no significant correlation in LSIL and chronic cervical inflammation(P＞0.05).Conclusion:In cervical squamous cell carcinoma and adenocarcinoma,the consistency of P16 expression and HPV DNA positivity are high,especially in HPV16/18 subtype.There is a good concordance between HR-HPV positivity and P16 protein overexpression.The positive expression of P16 in HSIL may initially reflect HPV infection status.However,in LSIL and chronic cervicitis,P16 expression may not accurately correlate with HPV infection.The inconsistency between P16 and HPV DNA testing could be influenced by multiple factors,including HPV subtypes,histopathological categories,specimen quality,and technical limitations.In clinical practice,it is recommended to conduct comprehensive analysis or employ multiple diagnostic methods to confirm HPV infection status for precise evaluation.

Objective:To investigate the clinicopathological features, immunophenotype, diagnosis and differential diagnosis of SRF-rearranged cellular perivascular myoid tumor.Methods:Two cases of SRF-rearranged cellular perivascular myoid tumor diagnosed in the Department of Pathology, Fudan University Shanghai Cancer Center from October 2021 to March 2022 were collected. Immunohistochemical staining, fluorescence in-situ hybridization (FISH) and next-generation sequencing (NGS) were performed, and the literature was reviewed.Results:Case 1, a 3-month-old boy presented with a painless tumor of the scalp, measuring about 2 cm in diameter. Case 2, a 3-year-old girl complained with a painless tumor of the knee, measuring approximately 1.5 cm in diameter. Microscopically, the tumor had a clear boundary and showed multinodular growth. The tumor was mainly composed of spindle cells arranged in long intersecting fascicles associated with thin, slit-like or branching ectatic vessels, focally forming hemangiopericytoma-like appearance. The tumor cells were abundant, but there was no obvious atypia. Mitotic figures (3-4/10 HPF) were noted. H-caldesmon and SMA were positive in both cases. Case 1 showed diffuse and strong positivity for Desmin, and focally for CKpan. Ki-67 proliferation index was 20% and 30%, respectively. FISH displayed NCOA2 gene translocation in case 1 and the RELA gene translocation in case 2. NGS detected the SRF-NCOA2 gene fusion in case 1 and the SRF-RELA gene fusion in case 2. Both patients underwent local excisions. During the follow-up of 5-14 months, case 1 had no local recurrence, while case 2 developed local recurrence 1 year post operatively.Conclusions:SRF-rearranged cellular perivascular myoid tumor is a novel variant of perivascular cell tumor, which tends to occur in children and adolescents. The tumor forms a broad morphologic spectrum ranging from a pericytic pattern to a myoid pattern, and include hybrid tumors with a mixture of pericytic and myoid patterns. Due to its diffuse hypercellularity and increased mitotic figures and smooth muscle-like immunophenotype, the tumor is easy to be misdiagnosed as myogenic sarcomas. The tumor usually pursues a benign clinical course and rare cases may locally recur.

Background and purpose:Urothelial carcinoma(UC)is a prevalent malignant tumor of the urinary system,and early diagnosis is crucial for improving patient prognosis.This study evaluated the diagnostic efficacy of fluorescence in situ hybridization(FISH),urine cytology and their combination for UC,as well as for its different subtypes.Methods:This study included patients who underwent transurethral resection of bladder tumor(TURBT)from January 2022 to December 2023 and approved by Ethics Commetce of Fudan Univesity Shanghai Cancer Center,No.:050432-4-2307E)that met the inclusion and exclusion criteria.We collected TURBT pathological results and pre-procedure FISH and cytology results.Diagnostic accuracy,sensitivity and specificity of FISH,cytology and their combination were analyzed and compared for urothelial carcinoma.The Strengthening the Reporting of Observational Studies in Epidemiology(STROBE)checklist and Standards for Reporting of Diagnostic Accuracy(STARD)were followed for this study.Results:A total of 283 patients were enrolled in this study,136 were diagnosed with UC,and 147 were not.Of the 136 UC cases,79(58.09%)were invasive and 57(41.91%)were non-invasive.In terms of malignancy grade,112(82.35%)were high-grade UC and 24(17.65%)were low-grade UC.Using histopathology as the gold standard,the accuracy of FISH,cytology and their combination in diagnosing UC was 79.51%,72.08%and 77.39%,respectively;sensitivity was 72.06%,58.82%and 78.68%,respectively;specificity was 86.39%,84.35%and 76.19%,respectively.The area under the curve(AUC)for FISH and the combination was similar but higher than that for cytology(0.792 vs 0.716,P=0.006;0.774 vs 0.716,P=0.004);the Net Reclassification Improvement(NRI)for FISH compared to cytology was 15.28%(P=0.006).In the 79 cases of invasive UC,FISH had higher accuracy than cytology(86.28%vs 78.32%,P=0.011).The sensitivity of FISH and the combination was higher than that of cytology(86.08%vs 67.09%,P=0.004;91.14%vs 67.09%,P＜0.001),and the AUC values were also higher(0.808 vs 0.713,P=0.004;0.784 vs 0.713,P=0.007).The NRI for FISH compared to cytology was 21.03%(P=0.003).In the 57 cases of non-invasive UC,the AUC values for all three methods were low(AUC＜0.700).Among the 112 cases of high-grade UC,FISH had higher accuracy(84.94%vs 76.45%,P=0.005),and the combination had higher sensitivity(89.29%vs 66.07%,P＜0.001)compared to cytology.The AUC values for FISH and the combination were also superior to that for cytology(0.847 vs 0.752,P=0.002;0.827 vs 0.752,P=0.001).The NRI for FISH compared to cytology was 19.01%(P=0.003).In the 24 cases of low-grade UC,the AUC values for all three methods were low(AUC＜0.600).Conclusion:For UC,particularly invasive and high-grade subtypes,FISH shows superior diagnostic efficacy compared to cytology.FISH alone offers accuracy and sensitivity comparable to the combination test,with higher specificity.In cases of non-invasive or low-grade UC,however,all three diagnostic methods demonstrate relatively low efficacy.

Background and purpose:Urothelial carcinoma(UC)is a prevalent malignant tumor of the urinary system,and early diagnosis is crucial for improving patient prognosis.This study evaluated the diagnostic efficacy of fluorescence in situ hybridization(FISH),urine cytology and their combination for UC,as well as for its different subtypes.Methods:This study included patients who underwent transurethral resection of bladder tumor(TURBT)from January 2022 to December 2023 and approved by Ethics Commetce of Fudan Univesity Shanghai Cancer Center,No.:050432-4-2307E)that met the inclusion and exclusion criteria.We collected TURBT pathological results and pre-procedure FISH and cytology results.Diagnostic accuracy,sensitivity and specificity of FISH,cytology and their combination were analyzed and compared for urothelial carcinoma.The Strengthening the Reporting of Observational Studies in Epidemiology(STROBE)checklist and Standards for Reporting of Diagnostic Accuracy(STARD)were followed for this study.Results:A total of 283 patients were enrolled in this study,136 were diagnosed with UC,and 147 were not.Of the 136 UC cases,79(58.09%)were invasive and 57(41.91%)were non-invasive.In terms of malignancy grade,112(82.35%)were high-grade UC and 24(17.65%)were low-grade UC.Using histopathology as the gold standard,the accuracy of FISH,cytology and their combination in diagnosing UC was 79.51%,72.08%and 77.39%,respectively;sensitivity was 72.06%,58.82%and 78.68%,respectively;specificity was 86.39%,84.35%and 76.19%,respectively.The area under the curve(AUC)for FISH and the combination was similar but higher than that for cytology(0.792 vs 0.716,P=0.006;0.774 vs 0.716,P=0.004);the Net Reclassification Improvement(NRI)for FISH compared to cytology was 15.28%(P=0.006).In the 79 cases of invasive UC,FISH had higher accuracy than cytology(86.28%vs 78.32%,P=0.011).The sensitivity of FISH and the combination was higher than that of cytology(86.08%vs 67.09%,P=0.004;91.14%vs 67.09%,P＜0.001),and the AUC values were also higher(0.808 vs 0.713,P=0.004;0.784 vs 0.713,P=0.007).The NRI for FISH compared to cytology was 21.03%(P=0.003).In the 57 cases of non-invasive UC,the AUC values for all three methods were low(AUC＜0.700).Among the 112 cases of high-grade UC,FISH had higher accuracy(84.94%vs 76.45%,P=0.005),and the combination had higher sensitivity(89.29%vs 66.07%,P＜0.001)compared to cytology.The AUC values for FISH and the combination were also superior to that for cytology(0.847 vs 0.752,P=0.002;0.827 vs 0.752,P=0.001).The NRI for FISH compared to cytology was 19.01%(P=0.003).In the 24 cases of low-grade UC,the AUC values for all three methods were low(AUC＜0.600).Conclusion:For UC,particularly invasive and high-grade subtypes,FISH shows superior diagnostic efficacy compared to cytology.FISH alone offers accuracy and sensitivity comparable to the combination test,with higher specificity.In cases of non-invasive or low-grade UC,however,all three diagnostic methods demonstrate relatively low efficacy.

Objective:To investigate MAML2 gene rearrangement, gene fusion patterns, and the clinicopathological characteristics of primary pulmonary mucoepidermoid carcinoma (PMEC).Methods:Forty-six cases of primary PMEC from Fudan University Zhongshan Hospital and Fudan University Shanghai Cancer Center between 2017 and 2020 were collected. MAML2 gene rearrangement in all cases was detected by fluorescence in situ hybridization (FISH). In 20 cases, MAML2 fusion patterns were detected by targeted RNA sequencing (RNAseq). The relationship between MAML2 gene rearrangement, fusion patterns, clinicopathological characteristics, and prognosis was analyzed.Results:The average age of PMEC patients was 41 years (range 15-71 years); the ratio of male to female was about 1.1 ∶ 1.0. Most PMECs were low grade in histopathology with an early clinical stage (stageⅠ-Ⅱ).The overall positive rate of MAML2 gene rearrangement detected by FISH was about 80.4% (37/46), and the rate was higher in low-grade PMEC (91.7%, 33/36). Of the 20 cases detected by RNAseq, all the 19 FISH positive cases showed gene fusion, mainly CRTC1-MAML2 fusion (16/19), the other three cases showed CRTC3-MAML2 fusion (3/19), the break point of all the fusion patterns was CRTC1/3 (exon 1)-MAML2 (exon 2); No gene fusion was detected in the single FISH negative case; Compared with the MAML2 FISH negative patients, the PMECs carrying CRTC1-MAML2 fusion were more commonly found in patients age ≤ 40 years, maximum tumor diameter ≤ 2 cm, low histopathological grade and early clinical stage (all P<0.05); The three PMECs carrying CRTC3-MAML2 fusion gene were all female with early clinical stage; Univariate analysis showed that MAML2 gene rearrangement/fusion, onset age ≤ 40 years old, smaller tumor size, low histopathological grade, early clinical stage, no metastasis at diagnosis and surgical treatment were significantly correlated with overall survival ( P<0.05), but Cox regression analysis suggested that none of the above indicators were the independent prognostic factors for the survival of PMEC. Conclusions:The high incidence of MAML2 gene rearrangement in PMEC suggests that it is an important molecular diagnostic marker of PMEC. RNAseq confirms that CRTC1/3-MAML2 is the main fusion pattern in PMEC, suggesting that MAML2 fusion transcription may be an important driving factor of PMEC. MAML2 rearrangement/fusion and related clinicopathological characteristics are associated with good prognosis.

Objective:To investigate the clinical value of the first multicolor fluorescence in situ hybridization (FISH) assay on multiple genes, and combined with 9p21 and 8q24 evaluation in the differential diagnosis of melanoma.Methods:Fifty-six melanomas and 36 benign melanocytic nevi diagnosed in Fudan University Shanghai Cancer Center from 2017 to 2019 were included. Each specimen was examined by first multicolor FISH assay targeting 6p25 (RREB1), 6q23 (MYB), 11q13 (CCND1) and CEP6, as well as 9p21 (CDKN2A) and 8q24 (MYC). The results of FISH assay in all cases were recorded according to Gerami′s criteria. Basing on the sensitivity and specificity of the first FISH assay, the refinement of diagnosis by adding combined 9p21 and 8q24 probes was further evaluated, as well as their association with different clinicopathological features.Results:In 86 cases, the FISH signals were adequate for analysis. Of the 56 melanoma cases, 52 cases were adequate for analysis; 36 cases (69.2%) were positive in the first FISH assay. The most frequent chromosomal anomaly was gain of RREB1 (30/52, 57.7%), followed by gain of CCND1 (20/52, 38.5%), loss of MYB relative to CEP6 (18/52, 34.6%) and gain of RREB1 relative to CEP6 (17/52, 32.7%). The frequency of homozygous deletions in 9p21 was 15.4% (8/52) and gain of 8q24 was 36.5% (19/52). Among the 36 melanocytic nevi cases, FISH results could be accurately evaluated in 34 cases, and none showed a positive result in the first FISH assay or 9p21 and 8q24 FISH analysis. Compared with the first FISH assay, the sensitivity of combination with 9p21 and 8q24 FISH analysis increased from 69.2% to 76.9% (40/52) and the specificity remained 100.0%. Statistical data showed that the rates of FISH positivity in patients with acral-lentiginious melanoma and nodual melanoma subtypes were higher than that in patients with superficial spreading melanoma and lentigo maligna melanoma subtypes, and patients with Breslow thickness>2.0 mm had higher positive FISH frequency than patients with Breslow thickness ≤2.0 mm.Conclusion:Multisite FISH analysis is a highly effective ancillary tool for the differentiation of unequivocal malignant from benign melanocytic lesions. By combining the first FISH assay with CDKN2A and MYC assay, the clinical utility of FISH analysis is further optimized in differential diagnosis of melanoma. Patients with Breslow thickness>2.0 mm, or acral-lentiginious melanoma and nodual melanoma subtypes tend to have higher FISH positivity. There remains a need to further explore the ancillary value of FISH analysis in diagnosis of ambiguous lesions.

Objective: To investigate clinicopathological, cytogenetic features and differential diagnoses of high grade endometrial stromal sarcoma (HGESS) with BCOR gene rearrangement. Methods: Five cases of HGESS with BCOR rearrangement were collected from consultant files (2016-2018) at Fudan University Shanghai Cancer Center. Interphase FISH was performed using a dual color break-apart probe. The clinical data, histologic features and immunohistochemical findings were reviewed. Results: All 5 cases occurred in adult women with a median age of 48 (range, 45-55) years. Abdominal pain and abnormal vaginal bleeding were the most common symptoms. Microscopically, the tumors showed mainly tongue-like and/or intersecting myometrial invasion. Stromal myxoid matrix and/or collagen plaques were prominent in all the cases. Most tumors consisted of uniform, haphazard fascicles of short spindle cells with mild to moderate nuclear atypia. Mitotic figures and necrosis were easily identified. Significant nuclear pleomorphism was not seen. Most tumors were rich in thick-walled small vessels. Prominent perivascular tumor cell whorling seen in conventional low-grade endometrial stromal sarcoma was not seen. All tumors expressed CD10 with only focal or absent desmin, SMA and/or h-caldesmon staining. ER or PR expression was seen in 4 tumors and 1 tumor showed both marker expression. Diffuse cyclin D1 was present in 2 tumors. BCOR immunoreactivity was present with strong staining in 3 cases and moderate staining in 1 case respectively. Ki-67 index ranged from 10% to 30%. Fluorescence in situ hybridization confirmed chromosomal aberration of BCOR gene in all tumors, that were previously diagnosed as myxoid leiomyosarcoma (2 cases), spindle cell uterine sarcoma (2 cases) and low-grade endometrial stromal sarcoma (1 case). Limited follow-up information revealed that 3/5 patients developed tumor recurrence, metastasis or death within one year. Conclusion BCOR rearranged HGESS has distinct morphological features and aggressive clinical behavior. In the presence of significant overlapping morphologic features between BCOR rearranged HGESS and other myxoid uterine mesenchymal tumors, especially myxoid leiomyosarcoma, molecular analysis is essential for accurate diagnoses.

Objective To investigate clinicopathological, cytogenetic features and differential diagnoses of high grade endometrial stromal sarcoma(HGESS) with BCOR gene rearrangement. Methods Five cases of HGESS with BCOR rearrangement were collected from consultant files (2016-2018) at Fudan University Shanghai Cancer Center. Interphase FISH was performed using a dual color break‐apart probe. The clinical data, histologic features and immunohistochemical findings were reviewed. Results All 5 cases occurred in adult women with a median age of 48 (range, 45-55) years. Abdominal pain and abnormal vaginal bleeding were the most common symptoms. Microscopically, the tumors showed mainly tongue‐like and/or intersecting myometrial invasion. Stromal myxoid matrix and/or collagen plaques were prominent in all the cases. Most tumors consisted of uniform, haphazard fascicles of short spindle cells with mild to moderate nuclear atypia. Mitotic figures and necrosis were easily identified. Significant nuclear pleomorphism was not seen. Most tumors were rich in thick‐walled small vessels. Prominent perivascular tumor cell whorling seen in conventional low‐grade endometrial stromal sarcoma was not seen. All tumors expressed CD10 with only focal or absent desmin, SMA and/or h‐caldesmon staining. ER or PR expression was seen in 4 tumors and 1 tumor showed both marker expression. Diffuse cyclin D1 was present in 2 tumors. BCOR immunoreactivity was present with strong staining in 3 cases and moderate staining in 1 case respectively. Ki‐67 index ranged from 10% to 30%. Fluorescence in situ hybridization confirmed chromosomal aberration of BCOR gene in all tumors, that were previously diagnosed as myxoid leiomyosarcoma (2 cases), spindle cell uterine sarcoma (2 cases) and low‐grade endometrial stromal sarcoma (1 case). Limited follow‐up information revealed that 3/5 patients developed tumor recurrence, metastasis or death within one year. Conclusion BCOR rearranged HGESS has distinct morphological features and aggressive clinical behavior. In the presence of significant overlapping morphologic features between BCOR rearranged HGESS and other myxoid uterine mesenchymal tumors, especially myxoid leiomyosarcoma, molecular analysis is essential for accurate diagnoses.

Objective: To investigate the clinicopathologic and genetic features, pathologic diagnosis and differential diagnosis of angiofibroma of soft tissue(AFST). Methods: The clinicopathologic characteristics of 24 cases diagnosed at Fudan University Shanghai Cancer Center from 2011 to 2017 were analyzed; immunohistochemical staining and interphase fluorescence in situ hybridization (FISH) were performed, and the literatures were also reviewed. Results: There were 15 male and 9 female (male∶female=1.7∶1.0) patients with age of onset ranging from 8 to 68 years (mean, 45 years). Fourteen cases occurred in extremities, including upper limbs (n=3) and lower limbs (n=11); seven cases were in the trunk, and 1 case each was in the temporal region, retroperitoneum and liver, respectively. Clinically, the tumors usually presented as a slowly growing painless mass. Tumor sizes ranged from 0.8 to 14 cm (mean 4.6 cm). Microscopically, most lesions were well-circumscribed, with fibrous capsules. Few cases infiltrated the surrounding fibrofatty tissue focally. The tumors were mainly composed of sparse short spindle cells and numerous small, branching, thin-walled blood vessels distributed in amyxoid, fibromyxoid or collagenous matrix, often accompanied by medium-sized, round or irregular and ecstatic vessels at the tumor periphery.By immunohistochemistry, all tested cases expressed vimentin (5/5), and showed variable positivity for EMA (2/4), ER (1/2), PR (2/3), α-SMA (1/18)and desmin (1/10). Ki-67 proliferation index were all less than 5%. CD34, CD31 and ERG staining clearly outlined the contours of blood vessels in the stroma. Four cases were tested for NCOA2 gene rearrangement by FISH, of which three were positive. Follow-up data was available in 17 patients (range, 3 to 69 months; mean, 30 months) were all free of disease. Conclusions Soft tissue angiofibroma is a benign fibroblastic neoplasm characterized by a prominent and complex vasculature set in a myxoid-to-collagenous stroma, and cytogenetically a distinctive NCOA2 gene rearrangement. Caution should be exercised for the possibility of potentially misinterpretation of AFST as vascular tumors and other myxoid soft tissue tumors.