Histologic Changes

The following picture and diagram indicate the usual distribution of granulomas in sarcoidosis: along bronchovascular bundles, interlobular septa, and pleura. Our case is unusual in the degree of involvement of the bronchovascular bundles.

The nodular variant of sarcoidosis (see later) may be an exuberant proliferation of granulomas around one or more bronchovascular bundles; e.g., an enlargement of the region indicated by the arrow to the "Bronchovascular bundle" shown here.

The histologic hallmark of sarcoidosis is the non-necrotizing granuloma. It consists of a rounded aggregate of histiocytes with increased amounts of pink cytoplasm (epithelioid cells), multinucleated giant cells of Langhans' (peripheral nuclei) and foreign body (diffuse nuclei) type, and lymphocytes.

These granulomas are diagnostic of sarcoidosis only when they occur in an appropriate clinical setting. Similar granulomas are found in many diseases, some of which are listed below.

 

Granulomas may be found in infectious diseases, beryllium disease, hypersensitivity pneumonia, response to neoplasm, certain drug reactions (methotrexate), eosinophilic pneumonia, and rarely in Langerhans' cell or Wegener's granulomatosis.

Clinical summary Image 4

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