Langerhans cells are differentiated cells of the monocyte-macrophage line that are found in the skin, reticuloendothelial system, pleura, and lungs. However, PHX generally involves the lungs and sometimes the bones. Other systems rarely are affected. Some patients experience spontaneous remissions while others progress to end-stage fibrotic lung disease.
Cigarette smoking is very important to disease activity.
Smoking worsens morbidity and mortality. Smoking cessation frequently stabilizes the disease and often leads to regression. Whites are afflicted at a higher rate than Asians and Blacks. No sexual predilection exists. Many are diagnosed incidentally after a screening chest radiograph.