Figure 2.

Granuloma macrophages invariably express carboxypeptidase-M (CPM) in uncommon lung disorders. (a) In allergic granulomatous alveolitis, the lesional cells (between thick arrows) are labeled more distinctly with CPM than CD163. As shown the same microscopic field (indicated by the same alveolus: a), CD163 decorates non-epithelioid reactive macrophages, also (slim arrows) which are negative for CPM. (b) Identical microscopic field of pulmonary cryptococcosis shows CPM positivity mainly in epithelioid cells (EPCs), as opposed to CD68, which decorates many more macrophages (arrowheads). Inset demonstrates the PAS-positive cryptococci with high magnification. (c) Wegener granulomatosis (vasculitis): as compared to the identical necrotizing inflamed vessels (indicated by the thick and slim arrows) and other compartments on serial sections, there is more prominent CPM staining in macrophages, mainly at sites of tissue damage (the fine cellular detail of the same image in higher magnification is seen in Supplementary Figure S2).