Objective: To investigate the clinicopathological features, immunophenotypes and molecular genetics of fibroma of tendon sheath (FTS). Methods: One hundred and thirty-four cases of FTS or tenosynovial fibroma diagnosed in the Department of Pathology, West China Hospital, Sichuan University, Chengdu, China from January 2008 to April 2019 were selected. The clinical and histologic features of these cases were retrospectively reviewed. Immunohistochemistry, fluorescence in situ hybridization (FISH) and reverse transcription-polymerase chain reaction (RT-PCR) were performed on the above cases. Results: There were a total of 134 cases of FTS, including 67 males and 67 females. The patients' median age was 38 years (ranged from 2 to 85 years). The median tumor size was 1.8 cm (ranged from 0.1 to 6.8 cm). The most common site was the upper extremity (76/134, 57%). Follow-up data was available in 28 cases and there was no detectable recurrence. Classic FTS (114 cases) were well-defined and hypocellular. A few spindle-shaped fibroblasts were scattered in the dense collagenous sclerotic stroma. Characteristically elongated slit-like spaces or thin-walled vessels were observed. Most of cellular FTSs (20 cases) were well-defined and the area with increased cellularity of the spindle cells coexisted with classic FTS. There were occasional mitotic figures, but no atypical mitotic figures. Immunohistochemistry was performed in 8 cases of classic FTS and most cases were positive for SMA (5/8). Immunohistochemistry was also performed in 13 cases of cellular FTS and showed 100% positive rate for SMA. FISH was conducted on 20 cases of cellular FTS and 32 cases of classical FTS. USP6 gene rearrangement was found in 11/20 of cellular FTS. Among 12 cases of CFTS with nodular fasciitis (NF)-like morphological feature, 7 cases showed USP6 gene rearrangement. The rearrangement proportion of USP6 gene in cellular FTS without NF-like morphological features was 4/8. By contrast, 3% (1/32) of the classic FTS showed USP6 gene rearrangement. RT-PCR was performed in those cases with detected USP6 gene rearrangement and sufficient tissue samples for RT-PCR. The MYH9-USP6 fusion gene was detected in 1 case (1/8) of the cellular FTSs, while no target fusion partner was detected in the classic FTS. Conclusions: FTS is a relatively rare benign fibroblastic or myofibroblastic tumor. Our study and recent literature find that some of the classic FTS also show USP6 gene rearrangements, suggesting that classical FTS and cellular FTS are likely to be at different stages of the same disease (spectrum). FISH for USP6 gene rearrangement may be used as an important auxiliary diagnostic tool in distinguishing FTS from other tumors.
Male ; Female ; Humans ; Gene Rearrangement ; In Situ Hybridization, Fluorescence ; Retrospective Studies ; Fibroma/pathology* ; Fasciitis/genetics* ; Ubiquitin Thiolesterase ; Tendons/pathology*

Humans ; Fasciitis/pathology* ; Fibroma/pathology* ; Gene Rearrangement ; Proto-Oncogene Proteins/genetics* ; Ubiquitin Thiolesterase

Ossifying fibroma (OF) and fibrous dysplasia (FD) are two fibro-osseous lesions with overlapping clinicopathological features, making diagnosis challenging. In this study, we applied a whole-genome shallow sequencing approach to facilitate differential diagnosis via precise profiling of copy number alterations (CNAs) using minute amounts of DNA extracted from morphologically correlated microdissected tissue samples. Freshly frozen tissue specimens from OF (n = 29) and FD (n = 28) patients were obtained for analysis. Lesion fibrous tissues and surrounding normal tissues were obtained by laser capture microdissection (LCM), with ~30-50 cells (5 000-10 000 µm
DNA Copy Number Variations ; Diagnosis, Differential ; Fibroma, Ossifying/genetics* ; Fibrous Dysplasia of Bone/genetics* ; Galactosyltransferases ; Humans ; Jaw ; Neoplasm Recurrence, Local ; Nuclear Proteins

Diagnosis, Differential ; Fasciitis/genetics* ; Fibroma ; Humans ; Panniculitis

OBJECTIVE: To investigate the BRAF gene mutations in ameloblastic fibroma (AF), and to further analyze the relationship between the BRAF mutation and clinical characteristics so as to provide new reference to the study of AF's molecular pathology. METHODS: Sixteen cases diagnosed as AF at the Department of Oral Pathology, Peking University School of Stomatology between January 1990 and December 2017 were collected. Genomic DNA was extracted from formalin-fixed, paraffin embedded tissues using the QIAamp DNA Mini Kit (Qiagen, Germany) according to the manufacturer's instructions. Polymerase chain reaction (PCR) and direct sequencings were used to detect the BRAF gene mutations. The clinicopathological data, such as the age, location of the lesion, symptoms and treatments were retrospectively analyzed. RESULTS: The sixteen cases of AF involved nine women and seven men aged 2-67 years. Three lesions occurred in the maxilla and thirteen in the mandible. The most common presenting symptom of AF was a painless slowly enlarging mass with swelling. Ten patients received conservative treatment and the other six patients received radical surgery. Three cases relapsed during the study period. BRAF gene mutation was found in sixteen of all the sixteen samples analyzed (100%). The BRAF mutation was a point mutation with a thymine-adenine transversion at nucleotide 1 799 of 15 exons, resulting in a change at residue 600 that substituted glutamine for valine. This mutation was the strongest activator of the downstream RAS/RAF/MEK/ERK-MAPK signaling pathway. This helped to bring about a gain-of-function mutation due to a V600E substitution. Many studies identified that BRAF regulated survival, apoptosis, and proliferation of cells by inducing MAPK pathways activation. For the existing cases, none of the age, sex, location, recurrence and treatments had a statistically significant correlation with BRAF mutation. CONCLUSION Our findings demonstrated high prevalence of BRAF V600E mutation in AF. The pathogenic role remains to be clarified．.
Adolescent ; Adult ; Aged ; Child ; Child, Preschool ; Exons ; Female ; Fibroma/genetics* ; Humans ; Male ; Middle Aged ; Mutation ; Proto-Oncogene Proteins B-raf/genetics* ; Retrospective Studies ; Young Adult

Diagnosis, Differential ; Fetus ; Fibroma ; metabolism ; pathology ; Fibrosarcoma ; congenital ; genetics ; metabolism ; secondary ; Hemangiopericytoma ; metabolism ; pathology ; Humans ; Kidney Neoplasms ; pathology ; secondary ; Liver Neoplasms ; pathology ; secondary ; Lung Neoplasms ; pathology ; secondary ; Male ; Nerve Sheath Neoplasms ; metabolism ; pathology ; Rhabdomyosarcoma, Embryonal ; metabolism ; pathology ; Soft Tissue Neoplasms ; congenital ; genetics ; metabolism ; pathology ; Vimentin ; metabolism