Fibroma of the Patellar Tendon Sheath: A New Paradigm.

The authors present a case of fibroma of the tendon sheath with intra-articular location in the knee, more specifically in the infrapatellar fat; with this specific location, this is the fourth case described of an entity that rarely affects large joints. Clinical and epidemiological aspects, but especially the imaging findings on magnetic resonance imaging scans, are essential for the differential and definitive diagnosis, which was nevertheless established only after a histological study of the excised mass by miniarthrotomy.

Multimodality imaging features of USP6-associated neoplasms.

Since the discovery of USP6 gene rearrangements in aneurysmal bone cysts nearly 20 years ago, we have come to recognize that there is a family of USP6-driven mesenchymal neoplasms with overlapping clinical, morphologic, and imaging features. This family of neoplasms now includes myositis ossificans, aneurysmal bone cyst, nodular fasciitis, fibroma of tendon sheath, fibro-osseous pseudotumor of digits, and their associated variants. While generally benign and in many cases self-limiting, these lesions may undergo rapid growth, and be confused with malignant bone and soft tissue lesions, both clinically and on imaging. The purpose of this article is to review the imaging characteristics of the spectrum of USP6-driven neoplasms, highlight key features that allow distinction from malignant bone or soft tissue lesions, and discuss the role of imaging and molecular analysis in diagnosis.

Fibroma of the Patellar Tendon Sheath: A New Paradigm / Fibroma da bainha do tendão patelar: Um novo paradigma

Abstract The authors present a case of fibroma of the tendon sheath with intra-articular location in the knee, more specifically in the infrapatellar fat; with this specific location, this is the fourth case described of an entity that rarely affects large joints. Clinical and epidemiologi-cal aspects, but especially the imaging findings on magnetic resonance imaging scans, are essential for the differential and definitive diagnosis, which was nevertheless established only after a histological study of the excised mass by miniarthrotomy.

Resumo Os autores apresentam um caso de um fibroma da bainha de tendão com localização intra-articular no joelho e origem na gordura infrapatelar. Esta localização específica é extremamente rara, sendo este o quarto caso descrito de uma entidade que raramente afeta grandes articulações. Para o seu diagnóstico aspetos clínicos, epidemiológicos e sobretudo achados imagiológicos da ressonância magnética são fundamentais. Neste caso o diagnóstico definitvo foi apenas estabelecido após estudo histológico da massa excisada por mini-artrotomia.

A Rare Bone Erosion due to Fibroma of the Tendon Sheath.

Introduction: Fibroma of the tendon sheath (FTS) is a soft-tissue tumor strongly attaches to the tendon sheath. The most common tumor which causes bone erosion is giant cell tumor of the tendon sheath while the erosion is quite rarely caused by FTS. Case Report: A 50-year-old housewife presented a swelling around the A1 pulley of the right third finger as well as bone erosion and a trigger finger. Against our preoperative suspect as GTTS, the pathological findings showed FTS. The snapping disappeared after the surgery. At 2.5 years postoperatively, we found no recurrence. Conclusion: FTS can be added to one of the differential diagnoses for tumor presenting bone erosion in fingers though our case is rare.

Cellular Fibroma of Tendon Sheath With Novel TNC-USP6 Gene Fusion Clinically Mimicking Arthritis in a 7-Year-Old Boy.

Cellular fibroma of tendon sheath (CFTS) is a rare, benign myofibroblastic neoplasm of tenosynovial soft tissues closely resembling nodular fasciitis (NF), but is histomorphologically distinct from classic fibroma of tendon sheath (FTS). We report a case of a pediatric patient with thumb swelling clinically concerning for arthritis with a biopsy demonstrating myofibroblastic proliferation with features consistent with NF/CFTS, and molecular studies confirming the presence of a USP6 gene fusion (TNC-USP6). This case highlights a unique clinical presentation of CFTS in a pediatric patient mimicking an inflammatory or reactive/non-neoplastic musculoskeletal disorder and the increasingly crucial role of molecular testing to differentiate a reactive myofibroblastic process from a neoplasm. Moreover, this report identifies TNC as a new fusion partner to USP6 fusion partner adding to our growing understanding of the USP6-rearranged family of tumors.

Ubiquitin-specific Peptidase 6 (USP6)-associated Fibroblastic/Myofibroblastic Tumors: Evolving Concepts.

Ubiquitin-specific peptidase 6 (USP6) is a hominoid-specific gene residing on chromosome 17p13 and serves as a deubiquitinating enzyme with a diverse set of functions including intracellular trafficking, inflammatory signaling, cell transformation and protein turnover. USP6 rearrangements were first identified in aneurysmal bone cysts, resulting in promoter swapping and over-expression of wild type USP6. Several morphologically overlapping fibroblastic/myofibroblastic tumors are known to harbor USP6 rearrangements, including nodular fasciitis, cellular fibroma of tendon sheath, myositis ossificans and fibro-osseous pseudotumor of digits. Over the past few years, fusions involving the USP6 gene and various partner genes have been described in these neoplasms. The current World Health Organization Classification of Tumors of Soft Tissue suggests that USP6-rearranged lesions are typically benign and usually self-limited in their growth. This review provides an updated overview of the clinical, histological and molecular genetic features of USP6-associated fibroblastic/myofibroblastic tumors and discusses how these lesions should be best classified.

Fibroma of tendon sheath of the hand in a 3-year-old boy: a case report.

BACKGROUND: Fibroma of tendon sheath (FTS) is a rare benign soft tissue tumor that often occurs in the upper extremities. It manifests as a slow-growing mass, often without tenderness or spontaneous pain. FTS occurs most commonly in people aged 20-40 years and is extremely rare in young children. Because FTS presents with atypical physical and imaging findings, it might be misdiagnosed as another soft tissue tumor such as a ganglion cyst or tenosynovial giant cell tumor (TSGCT). Although marginal resection is usually performed, a high rate of local recurrence is reported. CASE PRESENTATION: A boy aged 3 years and 1 month visited our outpatient clinic with a complaint of a mass of the left hand. An elastic hard mass approximately 20 mm in diameter could be palpated on the volar side of his left little finger. This mass was initially diagnosed as a ganglion cyst at another hospital. Ultrasonography revealed a well-circumscribed hypoechoic mass with internal heterogeneity on the flexor tendon. On magnetic resonance imaging (MRI), the mass showed iso signal intensity to muscle on T1-weighted images, and homogeneously low signal intensity to muscle on T2-weighted images. The mass was peripherally enhanced after contrast administration. FTS was initially suspected as the diagnosis on the basis of these imaging features. Because of the limited range of motion of his little finger, surgery was performed when he was 4 years old. Histopathological findings indicated the mass was well-circumscribed and contained scattered spindle cells embedded in a prominent collagenous matrix. The spindle cells contained elongated and cytologically bland nuclei with a fine chromatin pattern. Nuclear pleomorphism and multinucleated giant cells were not observed. On the basis of these findings, we made a diagnosis of FTS. One year after surgery, no signs of local recurrence were observed. CONCLUSIONS: We experienced an extremely rare case of FTS in the hand of a 3-year-old child. We especially recommend ultrasonography for hand tumors of young children to diagnose or eliminate ganglion cysts. MRI helped differentially diagnose FTS from TSGCT. Although marginal resection can be performed as a treatment, great care should be taken postoperatively because FTS has a high possibility of local recurrence.

USP6-Associated Neoplasms: A Rapidly Expanding Family of Lesions.

Nearly 20 years ago, the first description of a translocation involving chromosome 17 on which USP6 resides was described. Since then, not only the culprit gene but also many fusion partners, leading to transcriptional activation of USP6, have been detected. The first neoplasm known to harbor USP6 rearrangements was aneurysmal bone cyst. Since then, other entities like nodular fasciitis, myositis ossificans, fibro-osseous pseudotumor of digits, and a subgroup of fibromas of tendon sheath, probably representing tenosynovial nodular fasciitis, have been added to the list of USP6-rearranged lesions. Remarkably, all of them share clinical as well as morphological characteristics, and authors have suggested that these entities actually belong to the same spectrum. This review summarizes the current knowledge regarding USP6-rearranged lesions and further elaborates on how these neoplasms relate to one another. We propose to call these lesions UAN (Usp6-associated neoplasm).

Misses and near misses in diagnosing nodular fasciitis and morphologically related reactive myofibroblastic proliferations: experience of a referral center with emphasis on frequency of USP6 gene rearrangements.

Although harmless, reactive and benign neoplastic myo-/fibroblastic proliferations represent a diagnostic challenge in routine surgical pathology practice as reflected by their frequency among consultation cases. In addition to resembling each other, the prototypical nodular fasciitis (NF) and NF-like lesions can be mistaken for low-grade or aggressive sarcomas. USP6 translocation was reported recently as the molecular driver and potential diagnostic marker of NF. We reviewed 71 lesions with a diagnosis of NF (n = 48) or NF-like myofibroblastic proliferations (n = 23) and screened them for USP6 translocation by fluorescence in situ hybridization (FISH). Only one third of NFs were correctly diagnosed by submitting pathologists while one third was initially judged as malignant. NF was mentioned in the differential diagnosis in only half of the cases. A high Ki67/mitotic index, misleading immunohistochemistry (false-positive h-caldesmon), and unusual sites/circumscription were main causes behind overdiagnosis as malignant. FISH analysis revealed USP6 translocation in 74.4% of NF cases. None of the reactive/reparative myofibroblastic proliferations showed USP6 translocation. NF is still significantly misdiagnosed by general surgical pathologists, with a higher tendency toward overdiagnosis of malignancy. Inclusion of NF in the differential diagnosis of any fibromyxoid soft tissue lesion and awareness of its diverse morphology are mandatory to avoid misdiagnoses with the risk of disastrous overtreatment. In the appropriate clinicopathological context, USP6 gene translocation is a valuable adjunct for diagnosis of NF, particularly in limited biopsies. Absence of the USP6 gene translocation in NF-like reparative pseudosarcomatous myofibroblastic proliferations underlines their reactive nature and distinguishes them from NF which is currently considered a benign neoplasm with a self-limiting "transient" growth phase.

Fibroma of tendon sheath around large joints: clinical characteristics and literature review.

BACKGROUND: Fibroma of tendon sheath (FTS) is a benign tumor arising from the synovium of the tendon sheath that occurs mostly around small joints such as the fingers, hands, and wrist. However, FTS rarely arises around a large joint (knee, shoulder, elbow, and ankle) with intra-articular or extra-articular involvement. The clinical characteristics of FTS arising around a large joint are unclear. An additional 3 cases of FTS arising around a large joint are presented. Furthermore, the published cases and the present cases are reviewed with respect to their clinical characteristics and imaging and histopathology findings. METHODS: The 43 reported cases including the present 3 patients were summarized, and the patients' profiles, symptoms, sites and locations in the joint involved by FTS, magnetic resonance imaging (MRI) findings, surgical procedures, clinical courses, and cytogenetic analyses were reviewed. RESULTS: The average age of 26 cases was 40.9 years (range 13-69 years), and about 60% of the patients were male. About 10% of the patients had a past history of trauma to the knee joint. Of the present 3 cases, one case was extra-articular around the elbow joint, one case was extra-articular around the knee joint, and one case was intra-articular involving the knee joint. The common symptoms were pain (62.5%), swelling or palpable mass (54.2%), and limited range of motion of the involved joint (50%). The most commonly involved joint was the knee, with 32 cases (74.4%), followed by the elbow in 5 cases (11.6%), ankle in 4 (9.3%), and shoulder in 2 (4.7%). The tumor typically exhibited iso to low signal intensity on T1-weighted MRI. T2-weighted images showed various patterns, but mostly low signal intensity relative to muscle. The surgical margin was marginal resection in all cases. There were no recurrences after surgery. On chromosomal analysis, only the present Case 3 showed an abnormality. CONCLUSIONS: A total of 43 FTS cases that occurred around large joints were summarized. The most common site was around the knee joint. In FTS cases around large joints, it is necessary to distinguish between various fibroblastic and/or fibrohistiocytic tumors.

Arthroscopic Removal of Suprapatellar Fibroma of Tendon Sheath.

Intra-articular fibroma of tendon sheath is a rare disease. To our knowledge, less than 20 cases have been reported in the literature, and none of them was a Chinese patient. In this case report, we present a Chinese patient with intra-articular fibroma of tendon sheath of the knee joint which was excised arthroscopically. We also summarized the clinical presentation, diagnosis, and subsequent management of intra-articular fibroma of tendon sheath.

Intra-articular Fibroma of Tendon Sheath in Knee Joint Associated with Iliotibial Band Friction Syndrome: Rare Occurrence in a Teenage Girl.

INTRODUCTION: Iliotibial band (ITB) friction syndrome is a common overuse injury typically seen in active athlete population. A nodular lesion on the inner side of the ITB as an etiology or an accompanying lesion with friction syndrome has rarely been reported. Among such nodular lesions around knee, fibroma of tendon sheath (FTS) is a rare occurrence. All the more intra-articular occurrence is extremely rare. CASE REPORT: A 16-year-old female presented with recurrent pain and movable nodule at the lateral joint area, diagnosed as ITB friction syndrome. The nodule was confirmed as rare intra-articular FTS on the basis of histopathology findings. CONCLUSION: When nodular lesions around knee are detected on magnetic resonance imaging, a FTS could be included in the differential diagnosis. Etiology and pathogenesis of ITB friction syndrome should be revised in view of such rare presentations.

FOSL1 immunohistochemistry clarifies the distinction between desmoplastic fibroblastoma and fibroma of tendon sheath.

AIMS: Although desmoplastic fibroblastoma (DFB) and fibroma of tendon sheath (FTS) are well-established entities, they may show overlapping clinicopathological features. In addition, cytogenetic data showing a shared 11q12 rearrangement in a small number of cases suggest a close link between these entities. A recent microarray study revealed up-regulation of FOSL1 mRNA in DFBs with 11q12 rearrangement. The aim of this study was to clarify the relationship between DFB and FTS. METHODS AND RESULTS: We tested 42 cases diagnosed originally as either DFBs or FTSs for interobserver concordance based on the existing histological criteria and correlated the diagnosis with FOSL1 immunohistochemistry. In addition, FOSL1 gene status was determined by chromogenic in-situ hybridization (CISH). Using joint histological evaluation, 41 of 42 tumours were classified unanimously by three pathologists into 25 DFBs and 16 FTSs, whereas only one case received discordant opinions. Immunohistochemically, all DFBs showed diffuse, strong FOSL1 nuclear immunoreactivity (25 of 25, 100%), while none of the FTSs showed such overexpression. None of the selected 42 DFB mimics overexpressed FOSL1. FOSL1 was not rearranged in seven DFBs tested by CISH. CONCLUSIONS: We confirm here that DFB and FTS are two distinct entities that can be distinguished using the existing histological criteria. This distinction corresponds perfectly with FOSL1 immunohistochemical expression status, and diffuse strong FOSL1 expression specific to DFBs sharpens the border between the two categories. FOSL1 overexpression in DFB may not be caused directly by FOSL1 gene rearrangement. FOSL1 may also be a diagnostic aid for differentiating DFB from other histological mimics.

Fibroma of tendon sheath in planta.

PURPOSE: Fibroma of tendon sheath in planta is comparatively rare, and its differentiate diagnose, tumour features, treatment and complications were lack of retrospective study in clinics. METHODS: This was a retrospective study of 13 patients (seven women, six men) operated between July 2001 and May 2013 for FTS in planta. The average age at the time of the procedure was 49.8 ± 8.3 years old (range 31-64). The female-to-male ratio was 9:4. Before the surgery, anteroposterior, lateral and oblique position of foot X-rays were performed in all patients. Ultrasonography (n = 11) and magnetic resonance imaging (n = 11) were performed selectively. The tumor located on the metatarsal par (n = 6), the central part of plantar (n = 4), the lateral part (n = 2) and the medial part (n = 1). Eight patients presented with painless mass (62 % of cases), while five patients presented with pain mass (38 % of cases). No patient had bony erosion. This paper studies the different features of FTS and classifies them into two types-superficial type that tumour grows at planter fascia; deep type that breaks through the planter fascia growing around tendon and joint capsule. Eight and five patients were diagnosed as superficial type and deep type respectively. RESULTS: In all cases, the tumor was excised, pathological results was FTS. The mean follow-up period was 3.2 ± 1.1 years (range 2-7) years. Five patients had neurovascular bundle involvement (38 % of cases). Two patients had a recurrence (15 % of cases), they undergone another operation. Four patients had a pain (31 % of cases), two patients had numbness (15 % of cases), and one patient had pain and numbness (8 % of cases). They recovered after conservative treatment. CONCLUSION: For the FTS that grows in the plantar, we should select differential diagnosis and the corresponding therapy according to the features of two types, also the prognosis is different. LEVEL OF EVIDENCE: IV.

Fibroma of a tendon sheath causing Guyon's canal syndrome: case report.

This report presents a rare case of a 41-year-old woman with decreased sensation and weakness of grip of her left hand. On examination she had a well-defined mass on the ulnar-volar aspect of the wrist. Magnetic resonance imaging showed a focal nodular mass in Guyon's canal. Examination showed that the mass, 2.1 × 1.1 × 1.0 cm in size, originated in the proximal portion of the canal and was loosely associated with the tendon sheath of the flexor carpi ulnaris. The mass was removed and Guyon's canal released. Histological examination confirmed a diagnosis of fibroma of tendon sheath. Postoperatively, she had fully restored sensory and motor function of her left hand. The tumor has not recurred.

Intra-articular fibroma of tendon sheath in a knee joint associated with iliotibial band friction syndrome.

Iliotibial band (ITB) friction syndrome is a common overuse injury typically seen in the active athlete population. A nodular lesion on the inner side of the ITB as an etiology or an accompanying lesion from friction syndrome has been rarely reported. A 45-year-old male presented with recurrent pain and a movable nodule at the lateral joint area, diagnosed as ITB friction syndrome. The nodule was confirmed as a rare intra-articular fibroma of the tendon sheath (FTS) on the basis of histopathologic findings. We describe the MRI findings, arthroscopic and pathologic features, in this case of intra-articular FTS presenting with ITB friction syndrome.

Intra-Articular Fibroma of Tendon Sheath in a Knee Joint Associated with Iliotibial Band Friction Syndrome

Iliotibial band (ITB) friction syndrome is a common overuse injury typically seen in the active athlete population. A nodular lesion on the inner side of the ITB as an etiology or an accompanying lesion from friction syndrome has been rarely reported. A 45-year-old male presented with recurrent pain and a movable nodule at the lateral joint area, diagnosed as ITB friction syndrome. The nodule was confirmed as a rare intra-articular fibroma of the tendon sheath (FTS) on the basis of histopathologic findings. We describe the MRI findings, arthroscopic and pathologic features, in this case of intra-articular FTS presenting with ITB friction syndrome.

Fibroma of tendon sheath with 11q rearrangements.

Fibroma of tendon sheath is an uncommon, benign fibroblastic tumor that usually occurs in the upper extremities of young and middle-aged adults. A clonal chromosomal aberration, t(2;11)(q31-32;q12), has been described in one case. We herein present a unique cytogenetic finding of fibroma of tendon sheath arising in the first web space of the right hand of a 38-year-old woman. Physical examination showed a 3.5-cm, firm, mobile, non-tender mass. Magnetic resonance imaging showed a well-defined soft tissue mass with iso- to slightly-low signal intensity relative to skeletal muscle on both T1- and T2-weighted sequences. Contrast-enhanced T1-weighted sequences demonstrated moderate patchy enhancement of the mass. A fibroma or giant cell tumor of tendon sheath was suggested, and the lesion was marginally excised. Histological examination confirmed the diagnosis of fibroma of tendon sheath. Cytogenetic analysis revealed a novel t(9;11)(p24;q13-14) translocation among other karyotypic abnormalities. The postoperative course was uneventful, and the patient is doing well without local recurrence two months after surgery. To the best of our knowledge, this is only the second report of fibroma of tendon sheath with clonal chromosomal abnormalities.

Multiple fibromas of tendon sheath: unusual presentation.

Fibroma of the tendon sheath is an uncommon soft tissue tumor presenting as a solitary, slow-growing, firm, painless, small nodule, which shows strong attachment to the tendon or tendon sheath. It is usually localized on fingers and hand tendons in adults between the age of 20 and 40 years old. This case concerns a 61-year-old man presenting with a 5-year history of multiple cutaneous nodules on both palms and soles. Skin biopsy confirmed fibroma of the tendon sheath. Blood tests showed a high titer of rheumatoid factor and positivity to anti-nuclear antibody. No case of fibroma of the tendon sheath occurring multifocally on both palms and soles has been previously reported. Herein, we report on a very rare case of multiple fibromas of the tendon sheath arising from palms and soles, which supports the pathogenetic hypothesis that this tumor may be a reactive process rather than a true neoplasm.

Multiple Fibromas of Tendon Sheath: Unusual Presentation

Fibroma of the tendon sheath is an uncommon soft tissue tumor presenting as a solitary, slow-growing, firm, painless, small nodule, which shows strong attachment to the tendon or tendon sheath. It is usually localized on fingers and hand tendons in adults between the age of 20 and 40 years old. This case concerns a 61-year-old man presenting with a 5-year history of multiple cutaneous nodules on both palms and soles. Skin biopsy confirmed fibroma of the tendon sheath. Blood tests showed a high titer of rheumatoid factor and positivity to anti-nuclear antibody. No case of fibroma of the tendon sheath occurring multifocally on both palms and soles has been previously reported. Herein, we report on a very rare case of multiple fibromas of the tendon sheath arising from palms and soles, which supports the pathogenetic hypothesis that this tumor may be a reactive process rather than a true neoplasm.