Recurrent FOSL1 rearrangements in desmoplastic fibroblastoma.

The FOS gene family has been implicated in tumourigenesis across several tumour types, particularly mesenchymal tumours. The rare fibrous tumour desmoplastic fibroblastoma is characterised by overexpression of FOSL1. However, previous studies using cytogenetic and molecular techniques did not identify an underlying somatic change involving the FOSL1 gene to explain this finding. Prompted by an unusual index case, we report the discovery of a novel FOSL1 rearrangement in desmoplastic fibroblastoma using whole-genome and targeted RNA sequencing. We investigated 15 desmoplastic fibroblastomas and 15 fibromas of tendon sheath using immunohistochemistry, in situ hybridisation and targeted RNA sequencing. Rearrangements in FOSL1 and FOS were identified in 10/15 and 2/15 desmoplastic fibroblastomas respectively, which mirrors the pattern of FOS rearrangements observed in benign bone and vascular tumours. Fibroma of tendon sheath, which shares histological features with desmoplastic fibroblastoma, harboured USP6 rearrangements in 9/15 cases and did not demonstrate rearrangements in any of the four FOS genes. The overall concordance between FOSL1 immunohistochemistry and RNA sequencing results was 90%. These findings illustrate that FOSL1 and FOS rearrangements are a recurrent event in desmoplastic fibroblastoma, establishing this finding as a useful diagnostic adjunct and expanding the spectrum of tumours driven by FOS gene family alterations. © 2022 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Next-Generation Sequencing in the Diagnosis of Rare Pediatric Sinonasal Tumors.

The diagnosis of desmoid fibromatosis or other spindle cell tumors in the sinonasal region is very rare in children and needs to be thoroughly confirmed with immunohistochemical and/or molecular tests. We report 2 patients with such rare tumors and describe the use of next-generation sequencing in their evaluation. A 3-year-old female had a 4.4-cm midline nasal cavity mass involving the bony septum and extending into the base of the skull bilaterally. The moderate cellular fibroblastic proliferation revealed areas of thick keloid-like collagen bands and other areas with myxoid edematous stroma. Deep targeted sequencing identified a novel G34V mutation in the CTNNB1 gene consistent with desmoid fibromatosis. An 11-month-old male infant presented with a right nasal mass that extended through the cribriform plate into the anterior cranial fossa and involved the right ethmoid sinus and adjacent right orbit. Histology revealed an infiltrative atypical fibrous proliferation with focal calcifications that was negative for CTNNB1 and GNAS mutations. A novel RET E511K variant was identified in the tumor and later was also found in the germline and hence rendered of unknown significance. Both cases highlight the utility of next-generation sequencing in the evaluation of pediatric sinonasal spindle cell tumors that may have overlapping pathologic features. Reporting of rare or novel variants in tumor-only sequencing should be cautiously evaluated in children and pairing with germline sequencing may be needed to avoid the pitfall of assigning uncommon variants.

Fibroma desmoplástico / Desmoplastic fibroma

El Fibroma Desmoplástico es una patología poco frecuente y de localización mas conocida en maxilar inferior y pocos casos en tibia, fémur y otros huesos. En rótula no se encontraron casos en la abundante bibliografía consultada. Se presenta un caso en un paciente de 15 años que después de un año de tratamiento médico y fisiokinésico se hace RMN y TAC encontrando una imágen osteolítica en rótula izquierda, por lo que después de interconsulta con Ortopedista y Traumatólogo Infantil, se resuelve tratamiento quirúrgico. El objetivo de esta presentación es llamar la atención sobre dolor que se interpreta como tendinitis cuadricipital, con Rx. neg. y dolor en borde proximal de rótula y borde externo de la misma, pero los estudios mencionados nos orientan a una patología muy poco frecuente. Además se destaca que no se encontró en la bibliografía antecedente de otro caso similar en rótula. Se hace resección con margen de seguridad de la zona afectada incluyendo hueso y cartílago articular. La evolución fue satisfactoria, controlado a los 3 años no hay dolor ni limitación funcional. Tipo de estudio: Reporte de caso. Nivel de evidencia: IV

The Desmoplastic Fibroma is an unfrequent pathology and the most common location is in the lower jaw (there are a few cases in the tibia, femur and other bones). There wasn't found a case in the kneecap, despite the extensive bibliography consulted. It is presented a case of a 15 years old patient who after a year of medical and physio-kinesic treatment, underwent MRI and CT scans, finding an osteolytic image in the left patella. After consulting with an Orthopedist and a Child Traumatologist, it was resolved a surgical treatment. The purpose of this presentation is to draw attention to a pain in the proximal and outer edges of the patella interpreted as quadriceps tendonitis, without seeing anything in a radiography. It was made a resection, with a safety margin of the affected area, including bone and articular cartilage. There was a satisfying evolution, checked after 3 years, without pain or functional limitation. Type of Study: case report. Level of evidence: IV

Uncommon presentation of desmoplastic fibroblastoma on the tongue of a female patient.

Desmoplastic fibroblastoma (DF) is a rare benign soft tissue with spindle-to-stellate-shaped fibroblasts and myofibroblasts embedded in a prominent collagenous background. DF, mainly affecting subcutaneous and muscle tissue, very rarely occurs in the oral cavity. Hitherto, only one case of DF on the tongue has been reported. Here, we report another case. A 66-year-old woman was referred to our hospital with a mass formation in the tongue. On examination, a well-circumscribed, elastic, soft tumour with normal surface mucosa, measuring 13×12 mm, was observed on the left dorsal surface of her tongue. MRI and ultrasonography confirmed the mass, and a benign tongue tumour was suspected. The tumour was surgically resected under general anaesthesia 1 month later, leading to the histopathological diagnosis of DF. She experienced an uneventful clinical recovery after surgery, with no recurrence noted for more than 1 year postoperatively.

Desmoplastic fibroblastoma of the left upper arm.

An elderly female patient presented to the clinic with a several-week history of a mass in her left upper arm that was tender to the touch. The mass was initially thought to be a schwannoma of the left radial nerve based on imaging and was surgically removed. The pathology report revealed an uncommon diagnosis of desmoplastic fibroblastoma.

Diagnosis and Differential Diagnosis of Desmoplastic Fibroblastoma by Clinical, Radiological, and Histopathological Analyses.

BACKGROUND: Desmoplastic fibroblastoma (collagenous fibroma) is an uncommon benign soft-tissue tumor, rarely involving bone. It shares some overlapping features with other infiltrate tumors, such as desmoid-type fibromatosis, neurofibroma, and low-grade fibromyxoid sarcoma. The misdiagnosis may cause unnecessary surgical overtreatment, especially for those involving bone. In order to deepen the understanding of the diagnosis and differential diagnosis of desmoplastic fibroblastoma, we planned to analyze the clinical, radiological, and histopathological features and the outcome of desmoplastic fibroblastoma on the basis of case analysis and literature review. METHODS: Sixteen cases were retrieved from the surgical pathology records from May 2011 to April 2016 in the Department of Pathology in Beijing Jishuitan Hospital. Formalin-fixed, paraffin-embedded specimens of 16 cases of desmoplastic fibroblastoma were collected. Hematoxylin and eosin stain and immunohistochemistry were used to observe the histological features of desmoplastic fibroblastoma of soft tissue and bone. The images for diagnosis obtained from the ultrasonic examination, X-ray, magnetic resonance imaging, and computed tomography were used to observe the radiological features. Related literatures were retrieved from the PubMed and CNKI databases. RESULTS: Sixteen cases of desmoplastic fibroblastoma of soft tissue were located in the hand (n = 7), foot (n = 4), upper arm (n = 1), shoulder (n = 1), forearm (n = 2), and one case occurred in the proximal femur. Age ranged from 32 to 82 years (median age: 58 years). There were six females and ten males. Histologically, the lesions of soft tissue appeared as well-circumscribed masses with abundant collagenous matrix and low vascularity. Tumor cells were stellate- or spindle-shaped and uniformly distributed within the extracellular matrix. In five cases, the desmoplastic fibroblastoma were found to have infiltrated into the skeletal muscle tissue. In one case of desmoplastic fibroblastoma of bone, radiographs revealed osteolytically well-defined lesion. Immunohistochemistry stain showed that vimentin and smooth muscle actin were positive in all cases of desmoplastic fibroblastoma. CONCLUSIONS: Desmoplastic fibroblastoma (collagenous fibroma) has prominent clinical, histopathological, and radiological features. Before the differential diagnosis from other tumors is obtained by thorough analysis and comparison of the similar and different characteristics, the appropriate surgical management and accurate prognosis evaluation could not be delivered to the patient.

Desmoplastic Fibroblastoma in Maxillary Alveolar Bone Mimicking An Odontogenic Lesion: A Novel Case Report with Review of Literature.

Desmoplastic fibroblastoma (Collagenous fibroma) is a rare benign soft tissue tumor that disseminates widely and can be intramuscular or subcutaneously. There are seven reported cases in the oral cavity so far. We reported a novel case of collagenous fibroma that has been found in the anterior part of maxilla in a 58-year-old woman as an intraosseous radiolucent lesion that has been discovered during routine radiography. Histopathologically, spindle and stellate-shaped fibroblasts in a collagen-rich stroma as well as binucleated and multinucleated fibroblasts with prominent nucleoli were seen. Desmoplastic fibroblastoma could be found in jaw bones and excision of the lesion is curative, and no aggressive growth has been reported.

Desmoplastic fibroma versus soft-tissue desmoid tumour of forearm: a case series of diagnosis, surgical approach, and outcome.

We report a case series of aggressive fibromatosis of the forearm and discuss the differentiation criteria of overlapped intra- or extra-osseous origin of aggressive fibromatosis, surgical approach, and outcome. Ten cases of aggressive fibromatosis of the forearm were evaluated. When there was no involvement of vital adjacent structures, such as nerves, vessels, and tendons, en-bloc excision was performed for the removal of the soft-tissue mass. Bone involvement was observed in nine cases. Intercalary allograft was performed whenever one of the forearm bones was involved (six cases), while extensive curettage was used if both forearm bones were affected (three cases). The mean Musculoskeletal Tumor Society Score was 90%, ranging from 80% to 97%. Limited forearm rotation was the most frequent complication. Three local recurrences were observed, none with intercalary allograft reconstruction. We conclude that the extensive curettage of the involved bone results in a higher risk of local recurrence compared with intercalary allograft. LEVEL OF EVIDENCE: IV.

Fibroma desmoplásico: tumor benigno, con alto potencial de infiltración local / Desmoplasic fibroma: benign tumor, with high local infiltration capacity

El fibroma desmóplasico es una neoplasia benigna del tejido conjuntivo que tiene alta capacidad de infiltrar los tejidos adyacentes. En este artículo se presenta un caso clínico de una paciente de 3 a±os de edad con un fibroma desmoplßsico en la región sinfisiaria y en el cuerpo mandibular. El tratamiento fue la hemimandibulectomía y la colocación de injerto óseo autólogo y placa de reconstrucción. Se realizó una revisión de la literatura de este tumor benigno poco frecuente de la región maxilo facial...

Desmoplasic fibroma is a benign connective tissue tumor with high local infiltration capacity. This article presents a case of a 3-yearoldgirl who presented a desmoplasic fibroma in the mandible symphysis and body. The treatment was radical resection and placement of an autologous bone graft and reconstruction plate. A review of the published literature was done respect to this rare benign tumor of the maxillofacial region...

Invasive desmoplastic fibroblastoma in the chest wall.

Desmoplastic fibroblastoma is a rare soft tissue tumor. We present the case of a 61-year-old man with a growing chest wall tumor in the pleural cavity. After resection, the tumor was diagnosed as desmoplastic fibroblastoma. This is the first report of desmoplastic fibroblastoma occurring in the chest wall. Generally, desmoplastic fibroblastoma is considered as a benign and slow-growing tumor. However, the tumor in our patient grew very rapidly and invaded the adjacent lung, parietal pleura, and periosteum of the rib bone. We therefore describe this tumor as an "invasive" desmoplastic fibroblastoma.

Desmoplastic fibroma of the mandible: a series of three cases and review of literature.

The desmoplastic fibroma (DF) is a rare, fibroblastic lesion of bone that histologically resembles the desmoid tumor of soft tissue. Although classified as benign, it frequently demonstrates aggressive behavior, often causing tooth mobility, extensive bone destruction, and has a moderate to high recurrence rate. We present three cases of DF in the mandible: the first in a 13 year old female involving the mandibular body in the region of teeth #s 27-#28, the second in a 57 year old female with a lesion apical to tooth #30, and the third in a 20-year-old female involving the left posterior mandible. Clinical, histologic, immunohistochemical (IHC) and radiographic features of this rare neoplasm are discussed. The challenges encountered in establishing an accurate diagnosis due to significant microscopic overlap with other spindle cell lesions are also detailed. Additionally, the findings of IHC stains including vimentin, smooth muscle actin, S-100 protein, ß-catenin, HHF-35 and proliferation marker, Ki-67 on 3 cases are reported. The potential for misdiagnosis is high, especially in early lesions, since immunohistochemistry has been reported in literature to be inconsistent when differentiating DFs from other spindle cell lesions. A comparative review of DF and similar entities in the jaws with current considerations in treatment and prognosis is presented.

Desmoplastic fibroblastoma (collagenous fibroma) in the oral cavity.

Desmoplastic fibroblastoma (DF) also known as collagenous fibroma (CF) is a rare benign soft tissue tumor that occurs in varied locations in the body. Very few cases of DF have been reported in the oral cavity. We report a case of DF in an 8-year-old boy presented as a slow-growing mass in the buccal mucosa since 6 months. Histopathology, special staining and immunohistochemistry studies suggested a diagnosis of CF. As per our knowledge of the current literature this is the seventh case reported in the oral cavity and the first report in a child.

Abdominal and pelvic tumors with musculoskeletal histology.

This article is a case-based review of the broad spectrum of tumors with musculoskeletal histology that can arise in the abdomen or pelvis and involve the soft tissues, muscle, and bone. In this article, pathology-proven cases are presented with a focus on radiographic, computed tomography, magnetic resonance imaging, and positron emission tomography-computed tomography findings. The imaging features that differentiate tumors with musculoskeletal histology from more common abdominal tumors are discussed. Representative cases include malignant fibrous histiocytoma, chondrosarcoma, Ewing sarcoma, hemangiopericytoma, desmoplastic fibroma, neurofibrosarcoma, osteosarcoma, intimal sarcoma, liposarcoma, leiomyosarcoma, synovial sarcoma, teratoma, and chordoma. A variety of tumors with musculoskeletal histology can arise in the abdomen and pelvis. In some cases, unique imaging characteristics allow a confident diagnosis, whereas other cases have a more nonspecific appearance. Recognition of imaging features that suggest a musculoskeletal tumor including direct extension from a bone or neural foramen, the presence of cartilaginous or osseous matrix, or macroscopic fat would allow the radiologist to suggest the proper diagnosis. Recognizing imaging characteristics of tumors with musculoskeletal histology is important clinically as management and prognosis differ from that of more common abdominal tumors.

Imaging findings of desmoplastic fibroma rarely involving the clavicle: case report.

Desmoplastic fibroma of bone is a rare locally aggressive, but non-metastatic tumor. In this case report, we present a desmoplastic fibroma in an unusual location, the clavicle. Desmoplastic fibroma involving the clavicle is extremely rare, with only 2 reported cases before 1985. We report the imaging findings of a desmoplastic fibroma of the clavicle with a review of the relevant literature.

[Desmoplastic fibroma of the zygoma]. / Fibrome desmoplastique de l'os zygomatique.

INTRODUCTION: Desmoplastic fibroma is a benign and rare intraosseous tumor. This lesion is locally aggressive and has a high tendency to recur. OBSERVATION: The authors report the diagnostic and therapeutic management of a 26-year-old female patient who presented with a desmoplastic fibroma of the zygoma. DISCUSSION: This localization is extremely rare and only 2 cases have been reported. The clinical and radiological signs are pauci-specific. The diagnosis is most often established according to anatomopathology and immunohistochemistry results. The recommended management is extensive surgical resection.

Giant calvarial desmoplastic fibroblastoma.

We describe to our knowledge the first patient with giant desmoplastic fibroblastoma of the calvarium in a 20-year-old woman whose tumor first appeared at the age of 5 years. We also discuss the histopathological differential diagnosis, management dilemmas and complications of desmoplastic fibroblastoma.