Update on Pulmonary Langerhans Cell Histiocytosis.

Elzbieta Radzikowska

doi:10.3389/fmed.2020.582581

Abstract

Pulmonary Langerhans cell (LC) histiocytosis (PLCH) has unknown cause and is a rare neoplastic disorder characterized by the infiltration of lungs and various organs by bone marrow-derived Langerhans cells with an accompanying strong inflammatory response. These cells carry somatic mutations of BRAF gene and/or NRAS, KRAS, and MAP2K1 genes, which cause activation of the mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) signaling pathway. PLCH occurs predominantly in young smokers, without gender predominance. Lungs might be involved as an isolated organ or as part of a multiorgan disease. High-resolution computed chest tomography plays an outstanding role in PLCH diagnosis. The typical radiological picture of PLCH is the presence of small intralobular nodules, “tree in bud” opacities, cavitated nodules, and thin- and thick-walled cysts, frequently confluent. Histological examination of the lesion and demonstration of characteristic eosinophilic granulomas with the presence of LCs that display antigen CD1a or CD207 in immunohistochemistry are required for definite diagnosis. Smoking cessation is the most important recommendation for PLCH patients, but treatment of progressive PLCH and multisystem disease is based on chemotherapy. Recently, new targeted therapies have been implemented.

Highlights

Pulmonary Langerhans cell (LC) histiocytosis (PLCH) is a rare neoplastic disorder of unknown etiology, characterized by the infiltration of the lungs and various organs by bone marrow-derived LCs with an accompanying strong inflammatory response [1]
Isolated PLCH in children is extremely rare; the disease is reportedly associated with passive exposure to tobacco smoke in the majority of pediatric patients, and ∼10–30% of children with multisystem Langerhans cell histiocytosis (LCH) exhibit pulmonary lesions [11, 19]
Probable diagnosis of PLCH relies on clinical presentation confirmed radiologically

Summary

INTRODUCTION

Pulmonary Langerhans cell (LC) histiocytosis (PLCH) is a rare neoplastic disorder of unknown etiology, characterized by the infiltration of the lungs and various organs by bone marrow-derived LCs with an accompanying strong inflammatory response [1]. Isolated PLCH in children is extremely rare; the disease is reportedly associated with passive exposure to tobacco smoke in the majority of pediatric patients, and ∼10–30% of children with multisystem LCH exhibit pulmonary lesions [11, 19]. Tobacco smoke plays a major role in the development of PLCH [21] It causes inflammatory cell accumulation in the lungs; these cells include LCs, which release cytokines such as tumor necrosis factor alpha, interleukin 1 beta, granulocytemacrophage colony-stimulating factor, transforming growth factor beta, and the dendritic cell chemokine (chemokine ligand 20) [22]. Patients with spontaneous pneumothorax as an initial symptom of the disease are reportedly younger, more frequently men, and exhibit greater respiratory impairment compared with those who do not have pneumothorax [17]

Radiological Findings

12 ECD 2 LCH

CONCLUSIONS