The Clinicopathological And Molecular Genetic Studies Of Nodular Fasciitis

Background: Nodular fasciitis(NF)is a kind of common fibroproliferative disease in young adults,which grows fast and has reactivity and self limitation.due to its morphological characteristics of rapid growth,abundant fibroblast / myofibroblast proliferation and active cell division,NF is s easy to be misdiagnosed as various types of soft tissue tumors,especially as malignant tumors,which will bring unnecessary overtreatment to patients.On the essence of NF,the traditional view is that it is a kind of“pseudosarcomatous lesion”,However,since 2011,Erickson-Johnson has detected of USP6 gene rearrangement in NF cases with high frequency by FISH analysis,so it is suggested that NF is a clonal lesion.Considering its self limitation,some scholars suggest that NF may be a “transient neoplasia”,Since then,NF has gradually been accepted as a "transient" self-limiting tumor.Purpose: To summarize the clinical and pathological characteristics of nodular fasciitis,to study the occurrence rate of USP6 gene rearrangement in nodular fasciitis,and to explore the value of USP6 gene rearrangement in the diagnosis of nodular fasciitis.To improve the understanding,diagnosis and differential level of this disease.Methods: 45 cases of nodular fasciitis diagnosed in Chongqing Medical University from 2015 to 2020 were selected and analyzed clinically and pathologically.Meanwhile 30 cases from the above 45 cases and another 8 cases of spindle cell tumors with similar histological morphology were selected for USP6 gene rearrangement detection by fluorescence in situ hybridization(FISH).Results: Among the 45 NF cases selected in this group,21 were male and 24 were female;Most of them are aged between 20 and 55 years;The duration of the lesion ranged from 1-9 months;The lesions occurred in the upper limbs(17 cases)、Head and neck(12 cases)、trunk(10 cases)、lower limbs(6 cases);The tumor diameter was 0.5-4.0cm.They were composed of plump spindle cells arranged in short bundles or fascicles within a loose collagenous/myxoid stroma.Erythrocyte extravasation,mixed chronic inflammatory cells infiltration and microcystic changes were typically seen.Mitoses were present,with no atypical mitoses observed.The spindle cells were positive for SMA,and negative for Desmin,β-catenin,S-100、CD34、h-CALD.FISH results showed that USP6 gene rearrangement occurred in 30 cases of nodular fasciitis and negative in 8cases of control group.Conclusion: USP6 gene rearrangement detection is of great significance in the differential diagnosis of nodular fasciitis.It can effectively distinguish NF from various soft tissue sarcomas,which are easy to be confused with NF,and avoid misdiagnosis as malignant tumor.