Interstitial Pneumonias

Sarcoidosis

Granulomas tend to be along interlobular septa, bronchovascular bundles, or along the pleura. They tend to spare the alveolar parenchyma.

N.B. Beryllium disease is similar to sarcoidosis.

This well-defined, non-necrotizing granuloma is composed of epithelioid cells (histiocytes with abundant pink cytoplasm), multinucleated giant cells, and lymphocytes. Schaumann bodies and endogenous, birefringent crystals are sometimes present.

Variants show confluence of granulomas with progressive fibrosis and necrosis--nodular sarcoidosis (formerly called nodular sarcoidal angiitis). The peribronchiolar pink areas here represent scar. The nodules can be quite large and mimic metastatic tumor, radiographically.

Schaumann body

This laminated, shell-like (conchoidal) body (arrow) may have an associated birefringent crystalline component. Both are a product of the epithelioid histiocyte. As they enlarge, they may become extracellular. They are not specific for sarcoidosis, and may be found in other granulomatous diseases.

See also Case 33

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