The clinical significance of the FUS-CREB3L2 translocation in low-grade fibromyxoid sarcoma

Low-Grade Fibromyxoid Sarcomas with the Maxillary Sinus Localization: A Case Report and Review of the Literature

A low-grade fibromyxoid sarcoma (LGFMS) is an extremely rare tumor first described by Evans in 1987. LGFMS is a type of soft tissue sarcoma characterized by a deceptively benign histological appearance but completely malignant behavior. LGFMS is usually seen in the deep soft tissues of the extremities and trunk. We have examined many reviews, case reports and case series previously published in PubMed and Google Scholar. To date, only five cases have been reported in the maxilla. LGFMS generally affects young adults, but it can also be seen in children and older adults. A radical surgical approach is the most recommended treatment option. LGFMS has a very low mitotic activity; therefore, it is considered that neither chemotherapy nor radiotherapy has a significant effect on long-term LGFMS prognosis. However, to date, there has been no study suggesting any protocol for the follow-up of patients with LGFMS. In this report, we present a case with LGFMS located in the maxillary sinus, in which despite radiotherapy following extensive surgical excision, the tumor recurred in a short period of three months and reached its former size.

Low-grade fibromyxoid sarcoma: a clinicopathologic and molecular study of 10 genetically confirmed cases

Low-grade fibromyxoid sarcoma (LGFMS) is a rare low-grade malignant fibroblastic tumor, harboring a characteristic FUS-CREB3L2 or FUS-CREB3L1 gene fusion. The authors presented 10 genetically confirmed cases in a Chinese population. To the best of our knowledge, the present series consists of the most genetically confirmed cases from a Chinese medical center in English literature. The clinical, histologic, immunohistochemical, and molecular features of all cases are reviewed. The age of the patients (7 females, 3 males) ranged from 4 to 58 years old (median, 26 y; mean, 27 y). Trunk (4/10, 40%) was the most common site. Microscopically, all the cases exhibited an admixture of myxoid nodules and fibrous zones. The tumor cells were deceptively bland and nuclear pleomorphism was observed in focal areas of one case. Immunohistochemically, neoplastic cells were focally reactive for EMA (1/9, 11.1%), and negative for S-100 protein, CD34, smooth muscle actin, and desmin (0/9). Of the 4 cases stained with MUC4, one showed focal expression and others were interpreted as indeterminate. Surgical excision was performed for all patients. Follow-up information was available for 8 cases, and none developed local recurrence or metastasis at last follow-up (mean 31 months). LGFMS is a distinctive low-grade malignant tumor. The diagnosis of this tumor might be very challenging and it is mistaken for many benign lesions. A combination of clinical studies, careful morphologic analysis, and a full panel of immunomarkers especially genetic studies is helpful in confirming the diagnosis. This tumor type is associated with favorable prognosis.

A Rare Pathology: Low-Grade Fibromyxoid Sarcoma of the Maxilla

Low-grade fibromyxoid sarcoma (LGFMS) is a rare tumor with a benign histologic appearance and fully malignant behavior. To date, only 5 cases of LGFMS in the maxillofacial region have been reported. This report describes the case of a 16-year-old boy who was referred to the authors' hospital with an intraosseous myxofibroblastic tumor, probably of the LGFMS type, of the right maxilla. Radical resection with wide safe margins and secondary reconstruction with a free forearm flap were performed. Six-month follow-up showed no sign of recurrence or metastasis. The authors review the scientific literature and discuss different tumor locations and treatment strategies for those in the maxillofacial region. The present case is the sixth reported case of LGFMS in the maxillofacial region (intraosseous LGFMS of the maxilla), adding another facet to the literature regarding this rare soft tissue tumor.

Recurrent Low-Grade Fibromyxoid Sarcoma of the Neck: Report of a Case and Review of the Literature

Low-grade fibromyxoid sarcoma (LGFMS) represents a rare, indolent, benign neoplasm that proliferates at various anatomical locations. Histologically, the tumor consists of bland, deceptively benign-appearing spindle cells in a whirling pattern, as well as myxoid and collagenized stroma. The current treatment includes surgical excision. The aim of this investigation was to analyze a rare clinical case of recurrent LGFMS of the neck. Relevant literature is briefly reviewed. An 81-year-old male was admitted with an enlarging painless nontender mass in the neck. The patient referred a past medical history of LGFMS. Magnetic Resonance Imaging (MRI) depicted a large, well-defined mass in the lower neck and supraclavicular area, extending till the left upper area of the anterior thoracic wall. Based on the imaging characteristics and the medical history, a wide surgical excision of a 5.6 × 6.6 × 3.3 cm area, in close proximity to the cervical vertebrae was performed. On microsopic examination, the tumor contained alternating fibrous and mixoid components, with mixed hypo- and hyper-cellular areas, minimal necrosis and negligible cellular pleomorphism or nuclear atypia. As LGFMS is a soft tissue malignancy, any recurrences are usually local; therefore treatment of choice is radical, wide margin surgical excision. Nevertheless, the ideal goal of large safety margin of healthy tissue might be unattainable if it requires resection of vital anatomic structures. Because LGFMS has a very low mitotic rate, neither chemotherapy nor radiotherapy is expected to have significant effect on long-term prognosis.

Molecular diagnostics in soft tissue sarcomas and gastrointestinal stromal tumors

Soft tissue sarcomas are rare malignant heterogenous tumors of mesenchymal origin with over fifty subtypes. The use of hematoxylin and eosin stained sections (and immunohistochemistry) in the morphologic assessment of these tumors has been the bane of clinical diagnosis until recently. The last decade has witnessed considerable progress in the understanding and application of molecular techniques in refining the current understanding of soft tissue sarcomas and gastrointestinal stromal tumors beyond the limits of traditional approaches. Indeed, the identification of reciprocal chromosomal translocations and fusion genes in some subsets of sarcomas with potential implications in the pathogenesis, diagnosis and treatment has been revolutionary. The era of molecular targeted therapy presents a platform that continues to drive biomarker discovery and personalized medicine in soft tissue sarcomas and gastrointestinal stromal tumors. In this review, we highlight how the different molecular techniques have enhanced the diagnosis of these tumors with prognostic and therapeutic implications.

Deeply located low-grade fibromyxoid sarcoma with FUS-CREB3L2 gene fusion in a 5-year-old boy with review of literature

Background

Low-grade fibromyxoid sarcoma (LGFMS) is a rare soft tissue tumor typically affecting young to middle-aged adults. Despite its otherwise benign histologic appearance and indolent nature, it can have fully malignant behavior, and recurrence and metastasis may occur even decades later.

Case history

We report a case of LGFMS in the left lower leg of a 5-year-old Japanese boy. A magnetic resonance imaging (MRI) uncovered a well-demarcated intra-gastrocnemial tumor measuring 27 × 20 mm with a slightly high intensity on T1WI and heterogeneously high intensity on T2WI. Histologically, the tumor was composed of bland spindle-shaped cells with a whorled growth pattern. The tumor stroma was variably hyalinized and fibromyxoid with arcades of curvilinear capillaries and arterioles with associated perivascular fibrosis. Although LGFMS is known to affect children under 18 years of age, it is extremely rare in infants and children under 5 years of age. Despite the young age, this patient was accurately diagnosed by the typical histology and the detection of a FUS-CREB3L2 gene fusion.

Conclusion

Although LGFMS in children tends to be located superficially, this case presented with an intramuscular tumor in the region of the gastrocnemius. To the best of our knowledge, this is the first case of deep LGFMS arising in a child younger than 5 years of age. The patient is still alive with no evidence of the disease 4 months after diagnosis.

Virtual Slides

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/13000_2014_163

Peripheral nerve fibromyxoid sarcoma

Low-grade fibromyxoid sarcoma (LGFMS) is a rare soft-tissue neoplasm with metastatic potential and needs to be recognized as such, because it can be mistaken for other types of sarcoma due to its unremarkable appearance. This 49-year-old man presented with an approximately 5-cm mass on the anteromedial aspect of his left thigh that slowly increased over 10 years. Clinical symptoms were limited to local discomfort and intermittent distal numbness. Due to the location, imaging findings, and lack of serious symptoms, the initial differential diagnosis favored a schwannoma. An initial biopsy revealed histopathological findings consistent with a perineurioma, although with atypical features. The patient elected to have the mass excised, and the tumor, which arose from a branch of the saphenous nerve, could be separated well from the surrounding soft tissue. Histopathological investigation of the mass displayed characteristic features of a fibromyxoid sarcoma, which was confirmed by subsequent fluorescence in situ hybridization analysis. Due to concerns about infiltration beyond the margins, radical reexcision was advocated and performed, resulting in definite clear surgical margins. At follow-up, the patient had regained full strength with no residual neurological symptoms or any new deficits. He has since been healthy and disease free for a total of 4 years in follow-up. This case documents, to the authors' knowledge, the first observation of an LGFMS associated with a peripheral nerve. It also supports the use of fluorescence in situ hybridization analysis as an essential diagnostic method in establishing the diagnosis of LGFMS.

Low-Grade Fibromyxoid Sarcoma: Incidence, Treatment Strategy of Metastases, and Clinical Significance of the FUS Gene

Aim. The aim of this study was to assess the incidence of low-grade fibromyxoid sarcoma (LGFMS), present treatment results of metastatic LGFMS, and investigate the clinical significance of the FUS gene rearrangement. Methods. This study included 14 consecutive LGFMS patients treated at the Aarhus Sarcoma Centre in 1979-2010. Fluorescent in situ hybridization (FISH) analysis for FUS break-apart was performed for all patients. Results. The incidence of LGFMS was 0.18 per million, representing 0.6% of all soft tissue sarcomas. Four patients needed multiple biopsies/resections before the correct diagnosis was made. Four patients experienced local recurrence, and three patients developed metastases. The treatment of metastatic LGFMS varied from multiagent chemotherapy to repeated, selective surgery of operable metastases. The best response to chemotherapy was short-term stabilization of disease progression, seen with Trabectedin. The prevalence of the FUS break-apart was 21.4%. We found no significant difference in clinical characteristics and outcomes in correlation with the FUS break-apart. Conclusion. LGFMS is a rare disease with multiple challenges. The FUS break-apart was not associated with local recurrence or metastases in our study. To date the only treatment resulting in disease-free periods is surgery; however further investigation into the management of metastatic LGFMS is necessary.

Unusual histologic variant of a low-grade fibromyxoid sarcoma in a 3-year-old boy with complex chromosomal translocations involving 7q34, 10q11.2, and 16p11.2 and rearrangement of the FUS gene

Low-grade fibromyxoid sarcomas are rare, histologically deceptive, cytologically bland tumors that are infrequently encountered in pediatric patients. Our knowledge of histologic spectrum of these tumors is limited. A histologically unusual variant of a low-grade fibromyxoid sarcoma arising in a 3-year-old boy and containing islands of cohesive epithelioid cells is described. The diagnosis was, given the patient's age and the presence of epithelioid islands, very difficult and was verified by the presence of 3-way chromosomal translocations involving 7q34, 10q11.2, and 16p11.2 by rearrangement of the FUS gene and by immunoreactivity for mucin 4.