Figure 6

Characteristic histologic features of UIP. (a) Low magnification showing the heterogeneous appearing patchwork pattern of parenchymal involvement with areas of interstitial scarring alternating with islands of normal lung. Temporal variability is indicated by the presence of a fibroblast focus (arrow). (b) Higher magnification of the fibroblast focus shown in panel a. There is the characteristic proliferation of spindle cells within myxoid stroma. The cells are arranged with their long axis parallel to the long axis of the interstitium, and their luminal surface is covered by epithelium. (c) Another area from the same case showing honey-comb change (top) alternating with normal lung (bottom). The honey-comb areas are characterized by enlarged airspaces lined by bronchiolar epithelium and containing a mucinous exudate (shown at higher magnification in (d)).