Mesenchymal tumors of the lung: diagnostic pathology, molecular pathogenesis, and identified biomarkers

Abstract

Lung cancers are mainly composed of epithelial tumors such as carcinomas. Since mesenchymal tumors that arise in the lung are very rare, they have garnered little attention. The 2015 World Health Organization (WHO) classification of lung tumors has undergone revision, not only for carcinomas but also for mesenchymal tumors. The current version now includes PEComatous tumors, myoepithelial tumors, and pulmonary myxoid sarcomas with EWSR1-CREB1 translocation as new disease entities. To date, no review article has comprehensively summarized what is known about pulmonary mesenchymal tumors in accordance with the latest WHO classification. In this review, we attempt to summarize the data about these tumors in line with the 2015 WHO classification (except for pediatric tumors), focusing on their diagnostic pathology, molecular pathogenesis, and identified biomarkers for differential diagnoses. We also address the recently recognized pulmonary mesenchymal tumors that have not yet been included in the WHO classification. An increased understanding of the molecular characteristics of pulmonary mesenchymal tumors has the potential to provide clinicians with the best therapeutic options for patients with these tumors.

The clinicopathological challenges of symptomatic and incidental pulmonary hamartomas diagnosis

“…Similar findings were registered in our study group, with one exception, which displayed a dominant adipose tissue feature. The differential diagnoses in PHs include chondroma, lipoma, intrapulmonary solitary fibrous tumors (SFTs), leiomyoma, and well-differentiated chondrosarcoma [ 4 , 24 , 25 ]. In these situations, routine histopathological examination, associated with IHC exam, in selective cases, may certify the diagnosis.…”

“…In these situations, routine histopathological examination, associated with IHC exam, in selective cases, may certify the diagnosis. Histopathology reveals that chondromas are surrounded by a fibrous pseudocapsule, frequently show calcification, or bone metaplasia, and lack entrapped benign epithelium [ 25 ]. Lung lipomas are very rare benign tumors composed of mature adipose cells, underlying respiratory epithelium, which are rarely associated with osteocartilaginous metaplasia.…”

“…SFTs occasionally display an adenofibromatous pattern because of the entrapment of pulmonary epithelium, and these should be differentiated from PHs. However, SFTs rarely arise in lung, being composed of collagen fibers and fibroblastic spindle cells, which express immunopositivity for B-cell lymphoma-2 (Bcl-2), cluster of differentiation (CD)34, and CD99 [ 25 ]. Although excessive smooth muscle cells are not a specific feature for PHs, they may be sampled in lung biopsy that includes only one mesenchymal component and their presence can be certified by smooth muscular markers.…”

CT findings of a large primary pulmonary myxoid sarcoma: A case report

“…No immunohistochemical markers support the diagnosis of this tumor [ 7 , 11 ], although the majority express vimentin [ 6 , 11 ]. Nevertheless, other common markers are negative, particularly cytokeratins, S 100, smooth muscle actin, desmin, CD34, and neuroendocrine [6] .…”

Case Report: Hemangioblastoma- Like Clear Cell Stromal Tumor of the Left Lower Lung

“…Previously, it was uncommon to find Hemangioblastoma outside the central nervous system, although it has been reported in the liver, kidney, pancreas, and other parenchymal organs ( 2 ). Primary pulmonary neoplasms are mostly epithelial in origin, with adenocarcinoma being the most common; primary mesenchymal tumors of the lung are considered unusual ( 3 ). Therefore, it is extremely rare to find a hemangioblastoma-like clear cell stromal tumor in the lung.…”