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Figure 7. Histopathology Demonstrating UIP
(A) Low-magnification photomicrograph showing classical UIP/idiopathic pulmonary fibrosis (IPF)
pattern characterized by dense fibrosis with a predilection for subpleural and paraseptal parenchyma
with associated architectural distortion in the form of microscopic honeycomb change (arrow)
juxtaposed with relatively unaffected lung parenchyma. Visceral pleura is seen in the upper portion of
the figure. (B) Higher magnification photomicrograph showing subpleural scarring and honeycomb
change with associated fibroblast foci (arrow). (C) Low-magnification photomicrograph showing
probable UIP/IPF pattern characterized by subpleural and paraseptal predominant patchwork fibrosis
that is less well developed and lacks the degree of associated architectural distortion in the form of
either destructive scarring or honeycomb change illustrated in A and B. (D) Higher-magnification
photomicrograph showing patchy fibrosis and fibroblast foci (*) but without the extent of scarring and
honeycomb change illustrated in A and B. (E) Indeterminate for UIP/IPF pattern in which there is
mild nonspecific fibrosis that lacks a well-developed patchy and predominantly subpleural/paraseptal
distribution, architectural distortion, and fibroblast foci characteristic of classical UIP/IPF. ere is
associated osseous metaplasia, a common but nonspecific finding in UIP. Although these findings are
not diagnostic, they do not preclude a diagnosis of UIP/IPF in a patient with supportive clinical and
radiological findings.
