Primary pulmonary myxoid sarcoma in the interlobar fissure of the left lung lobe: a case report

• Published in: BMC pulmonary medicine Vol. 24; no. 1; pp. 313 - 8
• Main Authors: Xu, Ting, Wu, Li, Ye, Hua, Luo, Shuai, Wang, Jinjing
• Format: Journal Article
• Language: English
• Published: England BioMed Central Ltd 03.07.2024; BioMed Central; BMC
• Subjects: Actin; Antigens; Asymptomatic; Cancer; Case Report; Case reports; Cell proliferation; Chemotherapy; Chondrosarcoma; Diagnosis; Extraskeletal myxoid chondrosarcoma; FLI-1 protein; Gene fusion; Histiocytoma; Humans; Inflammation; Kinases; Lung - diagnostic imaging; Lung - pathology; Lung cancer; Lung lobe interlobar fissure; Lung Neoplasms - diagnosis; Lung Neoplasms - genetics; Lung Neoplasms - pathology; Lymphatic system; Male; Metastases; Metastasis; Muscle proteins; Myxosarcoma - diagnosis; Myxosarcoma - genetics; Myxosarcoma - pathology; Myxosarcoma - surgery; Oncogene Proteins, Fusion - genetics; Patients; Plasma; Primary pulmonary myxoid sarcoma; Radiation therapy; Russell bodies; Sarcoma; Sarcoma - diagnosis; Sarcoma - genetics; Sarcoma - pathology; Sarcoma - surgery; Smooth muscle; Stroma; Tomography, X-Ray Computed; Tumor cells; Tumors; Vimentin; Young Adult; Diagnosis; Lung lobe interlobar fissure; Primary pulmonary myxoid sarcoma; Russell bodies
• ISSN: 1471-2466; 1471-2466
• DOI: 10.1186/s12890-024-03085-8

Primary pulmonary myxoid sarcoma (PPMS) is a rare, low-grade malignant tumor, constituting approximately 0.2% of all lung tumors. Despite its rarity, PPMS possesses distinctive histological features and molecular alterations, notably the presence of EWSR1-CREB1 gene fusion. However, its precise tissue origin remains elusive, posing challenges in clinical diagnosis. A 20-year-old male patient underwent a routine physical examination 6 months prior, revealing a pulmonary mass. Following surgical excision, microscopic evaluation unveiled predominantly short spindle-shaped tumor cells organized in a fascicular, beam-like, or reticular pattern. The stromal matrix exhibited abundant mucin, accompanied by lymphocytic and plasma cell infiltration, with Russell bodies evident in focal areas. Immunophenotypic profiling revealed positive expression of vimentin and epithelial membrane antigen in tumor cells, whereas smooth muscle actin and S-100, among others, were negative. Ki-67 proliferation index was approximately 5%. Subsequent second-generation sequencing identified the characteristic EWSR1-CREB1 gene fusion. The definitive pathological diagnosis established PPMS. The patient underwent no adjuvant chemotherapy or radiotherapy and remained recurrence-free during a 30-month follow-up period. We report a rare case of PPMS located within the left lung lobe interlobar fissure, featuring Russell body formation within the tumor stroma, a novel finding in PPMS. Furthermore, the histomorphological characteristics of this case highlight the diagnostic challenge it poses, as it may mimic inflammatory myofibroblastic tumor, extraskeletal myxoid chondrosarcoma, or hemangiopericytoma-like fibrous histiocytoma. Therefore, accurate diagnosis necessitates an integrated approach involving morphological, immunohistochemical, and molecular analyses.