Fig. 4
From: Fibrosing pneumonia – how to diagnose, and how to recognize the etiology?
Myofibroblastic foci at different age are shown; a), b), and c) young myofibroblastic foci with few cells (a and b) and abundant myxoid matrix, in c) more cellular lesion but still myxoid matrix; in e) and f) there is focal maturation of the myofibroblasts, characterized by an eosinophilic cytoplasm and collagen fibers; in h) young and old myofibroblastic foci are side by side. This nicely demonstrate the development of these lesions, where the myofibroblasts change their phenotype and slowly acquire a more fibroblastic one. H&E, bars 50, 20, and 10 μm, respectively