Erdheim-Chester disease

Bone tumors are a rare and heterogeneous group of neoplasms that occur in the bone. The diversity and considerable morphologic overlap of bone tumors with other mesenchymal and nonmesenchymal bone lesions can complicate diagnosis. Accurate histologic diagnosis is crucial for appropriate management and prognostication. Since the publication of the fourth edition of the World Health Organization (WHO) classification of tumors of soft tissue and bone in 2013, significant advances have been made in our understanding of bone tumor molecular biology, classification, prognostication, and treatment. Detection of tumor-specific molecular alterations can facilitate the accurate diagnosis of histologically challenging cases. The fifth edition of the 2020 WHO classification of tumors of soft tissue and bone tumors provides an updated classification scheme and essential diagnostic criteria for bone tumors. Herein, we summarize these updates, focusing on major changes in each category of bone tumor, the newly described tumor entities and subtypes of existing tumor types, and newly described molecular and genetic data.

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“…ECD is a clonal systemic histiocytosis with inflammation and fibrosis 182. ECD is a rare but likely underdiagnosed disease.…”

Section: Who Classification Of Bone Tumorsmentioning

confidence: 99%

“…They may also be positive for factor XIIIa and fascin, and less commonly for S100 protein. Expression of phosphorylated ERK is frequent in ECD histiocytes, and strong diffuse cytoplasmic VE1 overexpression may signal a BRAF p.Val600Glu mutation 182…”

Section: Who Classification Of Bone Tumorsmentioning

confidence: 99%