纤维软骨性间叶瘤2例并文献复习OA

Fibrocartilaginous mesenchymoma(FM)is a rare primary bone tumor.Morphologically,it shares certain similarities with fibrocartilaginous dysplasia,low-grade central osteosarcoma,and dedifferentiated chondrosarcoma,which may lead to misdiagnosis.In this study,clinical and imaging data of two FM cases diagnosed by small biopsy specimens in February 2023 at the Department of Pathology,Yunnan Cancer Hospital,were collected.Their pathological features,immunophenotype,and molecular characteristics were retrospectively analyzed.Both cases were male adolescents aged 14 and 13 years.The tumors were located in the left superior pubic ramus and the right ischiopubic junction,respectively.Both showing expansile osteolytic destruction.Histologically,both cases exhibited cartilage nodules resembling epiphyseal plate cartilage,bland spindle cells,and trabecular bone structures rimmed by osteoblasts.In Case 1,cystic wall-like structures were observed in focal hemorrhagic areas,with osteoclast-like giant cells lining the cyst wall,indicating secondary aneurysmal bone cyst formation.Neither case showed expression of isocitrate dehydrogenase(IDH)1/IDH2 proteins,mouse double minute 2 homolog(MDM2)protein,or cyclin-dependent kinase 4(CDK4)protein.No mutations in the guanine nucleotide-binding protein α-stimulating activity polypeptide(GNAS)gene or IDH1/IDH2 genes were detected.Based on literature review,FM is a rare primary intraosseous borderline tumor that mainly occurs in adolescents and commonly involves the metaphysis of long bones,ilium,pubis,vertebrae,and ribs.The main histological features include hyaline cartilage nodules,bland spindle cells,and newly formed trabecular bone rimmed by osteoblasts.FM lacks specific immunophenotypic and molecular genetic alterations.It has a tendency for local recurrence and should be differentiated from fibrocartilaginous dysplasia,low-grade central osteosarcoma,and dedifferentiated chondrosarcoma.Complete surgical resection can achieve a favorable prognosis.Diagnosis of FM in small biopsy specimens requires comprehensive evaluation of clinical,pathological,and imaging findings to avoid missed or incorrect diagnosis.