Low-Grade Fibromyxoid Sarcoma: A Rare Case in an Unusual Location

Abstract

Introduction Low-grade fibromyxoid sarcoma, also known as Evans tumor, is a low-grade sarcoma that most commonly arises in the deep soft tissue of the proximal extremities or trunk in young adults. It is very rare in the viscera as a primary site with only a few cases reported in the literature. Here we present a case of Evans tumor occurring in an unusual and rarely reported location: the mediastinum. Method A 32-year-old male presented with history of persistent cough, and subsequent imaging revealed a left diaphragmatic tumor measuring around 11 cm with associated chest wall implants. Grossly, the tumor was well circumscribed, arising from the parietal pleura with attachment to both lung and diaphragm and focally involving visceral pleura with no extension into the underlying lung parenchyma. Histologically, the tumor was composed of uniform and bland-appearing spindle cells interspersed among large areas of hyalinized rosettes, so-called giant rosettes. By immunohistochemistry, the tumor was positive for EMA, bcl-2, TLE-1, and MUC-4 and negative for STAT-6, ruling out solitary fibrous tumor. FISH for SYT gene rearrangement was performed and was negative, ruling out synovial sarcoma. Given the overall morphology and the phenotype, the final diagnosis was low-grade fibromyxoid sarcoma with giant collagen rosettes (also known as hyalinizing spindle cell tumor with giant rosettes). Conclusion Mediastinal low-grade fibromyxoid sarcoma is a rare entity that should be considered in the differential diagnosis of visceral soft tissue tumors. Pathologic examination and a thorough immunohistochemical and molecular workup play a vital role in establishing this rare and challenging diagnosis.

Rare case of low-grade fibromyxoid sarcoma of the thoracic wall with complete sternum reconstruction

“…Pericollagenous rosettes, hypercellularity and other variable features have been described, but the differences do not seem to affect tumor behavior or overall survival [ 2 , 4 ]. Immunohistochemically, the tumor is typically positive for MUC4 and negative for CD-34, S-100 protein, ALK-1 SMA [ 2–6 , 12 , 14 ]. Cytogenetic analysis shows aberrancies with t(7;16) (q34;p11) translocations resulting in fusion of FUS and CREB3L2 genes, with its resulting chimeric protein present in 95% of well-defined LGFMS [ 2–6 , 9 , 12–14 ].…”

“…Immunohistochemically, the tumor is typically positive for MUC4 and negative for CD-34, S-100 protein, ALK-1 SMA [ 2–6 , 12 , 14 ]. Cytogenetic analysis shows aberrancies with t(7;16) (q34;p11) translocations resulting in fusion of FUS and CREB3L2 genes, with its resulting chimeric protein present in 95% of well-defined LGFMS [ 2–6 , 9 , 12–14 ].…”

Low-grade fibromyxoid sarcoma incidentally discovered as an asymptomatic mediastinal mass: a case report and review of the literature

“…Alive without remission or residual symptoms in 2 months of follow-up Galetta et al [ 3 ] 2004 41/M 8 × 4 × 3 Behind the thymus Vascularized myxoid sarcoma with hyalinized collagenous and spindled-shaped areas Surgical resection Alive without remission or residual symptoms in 35 months of follow-up Jakowski et al [ 4 ] 2008 44/F 12 Arose from the right epicardium at the atrioventricular groove adherent to the right ventricular free wall Admixture of hypocellular myxoid and hyper-cellular spindle cell areas in a collagenous stroma with numerous large hyalinized collagen rosettes Surgical resection Alive without remission or residual symptoms in 7 months of follow-up Gulhan et al [ 5 ] 2012 25/F 17 × 13 × 11 Posterior mediastinum, compressing on the anterior mediastinal formations Lesion formed by spindle-shaped cells was visible in the myxoid and hyalinized stroma. Giant collagen rosettes were also visualized Surgical resection Discharged in a stable condition after 11 days and no subsequent follow-up Maedah et al [ 6 ] 2009 2 cases 19/F 50/M 23.5 × 10 × 21.5 13 × 13 × 13 CT measurements 20 × 10 × 21 11 × 7.2 × 11.5 Case 1: Anterior mediastinum Case 2: Right superior mediastinum Three distinct zones were noted: hyper-cellular zones with islands of collagen fibers, hypo-cellular zones with abundant myxoid stroma, and prominently hyalinized zones Surgical resection of all the cases C1: Recurrence of anterior mediastinal mass after 5 years C2 Alive without remission or recurrence in 5 years of follow-up Pervez et al [ 7 ] 2019 32/M 11 Tumor arising from the parietal pleura with attachments to both lung and diaphragm Tumor was ...…”

“…Primary mediastinal sarcomas are rarer than ever. To the best of the authors’ knowledge and the literature search performed, only seven cases of primary mediastinal LGFMS have been reported [ 2 – 7 ], and this is an additional rare case of primary mediastinal LGFMS with typical histological findings, which was confirmed by immunohistochemical (IHC) stains [ 8 ].…”

Low‐grade fibromyxoid sarcoma arising from the lung: A case report

“…Complete resection is the standard treatment strategy, similar to other primary pulmonary sarcomas. 7 , 11 , 12 , 13 On the other hand, conventional systematic therapy has limited efficacy in LGFMS. However, National Cooperative Sarcoma Groups are conducting a clinical trial on combination trabectedin and radiotherapy for some types of sarcomas including LGFMS (TRASTS study).…”