Giant primary low-grade fibromyxoid sarcoma arising from the left pulmonary parenchyma: A case report and literature review

Thoracoscopic Wedge Resection for Low-Grade Fibromyxoid Sarcoma (Evans Tumor) with Massive Calcification and Originating from the Lung: A Rare Case in an Unexpected Location

We encountered a rare case of low-grade fibromyxoid sarcoma, which is generally known as Evans tumor, with massive calcification originating from the lung. The patient was a 22-year-old man with Duchenne muscular dystrophy who was referred for a detailed investigation of an intrathoracic tumor with massive calcification. Although our preoperative diagnosis was a solitary fibrous tumor originating from the mediastinum or diaphragm, intraoperative thoracoscopy revealed the tumor arising from the left lower lobe without adhesion to the other organs. Considering his medical history, we aimed to preserve lung function and chose wedge resection, which completely removed the tumor. Based on the pathological findings, the tumor was diagnosed as low-grade fibromyxoid sarcoma with massive calcification originating from the lung. Although extremely rare, this tumor should be considered as a differential diagnosis for a solitary lung mass with massive calcification in young adults.

Case report: Primary pleural low-grade fibromyxoid sarcoma in a 4-year-old boy with molecular confirmation

Low-grade fibromyxoid sarcoma (LGFMS) is a rare malignant fibroblastic tumor, principally affecting the deep tissues of the proximal trunk and extremities in young adults. However, primary pleural LGFMS is extremely rare, and only three cases have been reported in the previous English literature without genetic confirmation. Furthermore, the historical pleural LGFMS cases were all adults, and the primary pleural LGFMS in children has never been reported to date. Here, we presented a primary pleural LGFMS in a 4-year-old boy with detailed clinical, pathological, and molecular results. Histologically, the current tumor showed typical alternating collagenous and myxoid areas, containing spindled or oval tumor cells arranged in a whorled and short fascicular pattern. In some areas, the tumor cells exhibited moderate atypia, and mitotic figures were identified but without the identification of giant collagen rosettes. Immunohistochemically, all the neoplastic cells showed strong and diffuse positivity for MUC4. Genetically, FUS gene rearrangement was revealed by fluorescence in-situ hybridization (FISH), and subsequently, next-generation sequencing (NGS) and polymerase chain reaction (PCR) further demonstrated the FUS::CREB3L2 fusion transcript. To the best of our knowledge, this is the first case of primary pleural LGFMS with the identification of FUS gene rearrangement and FUS::CREB3L2 fusion in a 4-year-old child. Our study expands the age range of pleural LGFMS and highlights the combination of morphological, immunohistochemical, and molecular analyses in such challenging cases.