Usual interstitial pneumonia (UIP)

This gross photo is from a patient with UIP. This entity is characterized by heterogeneous distribution of varying degrees of involvement; in this case variation from relatively normal to fibrotic to end-stage honeycombing.

This section is from a region of advanced disease showing extensive interstitial fibrosis. One can still distinguish lighter areas of loose connective tissue in which there is a continuing process of fibrosis.

Fibroblastic foci are a prominent feature of UIP. Here one sees such a focus of loose connective tissue with fibroblasts. A few chronic inflammatory cells are seen but they are usually not prominent in this entity.

From the slide collection of the late Dr. Charles Kuhn