Pulmonary tuberculosis and centrilobular emphysema. The "upright theory" of apical localization.

Abstract

<h3>Introduction</h3> Emphysema may be defined as dilatation of respiratory air spaces with destruction of the intervening septa. Understanding of the pathologic anatomy of emphysema has been greatly enhanced by studies of inflation-fixed lung specimens carried out over the past two decades. We have recently reviewed the literature on this topic¹and will not do so here. Briefly, two major anatomic patterns have emerged from these studies. They have been named centrilobular and panlobular emphysema on the basis of their localization in the secondary lung lobule of Miller.²Centrilobular emphysema presents as a focal area of air space dilation located at or near the center of the secondary lobule; the air spaces at the periphery of the lobule tend to be preserved till the disease is far advanced. The process has been shown to start with dilation of the respiratory bronchiole with subsequent involvement of adjacent air spaces. Panlobular