Angiitis and Nodule Formation (Granulomatosis)

The active angiitis in the vicinity of the nodules shown on the previous page suggests that it plays a role in their development.

Here, we see a narrowed, inflamed artery with focal destruction of elastic layers leading into a cavitary nodule at the right.

Progressive inflammation and necrosis in and around a vessel may cause enlargement of the nodule. Note how the inflammation also appears to be involving arterial branches (arrows). Elastic van Gieson stain

This artery (arrows mark the media) was adjacent to a large nodule to the right (not shown). Its lumen and part of its wall to the left are obliterated by necrosis surrounded by a granulomatous response indicating the formation of a new nodule here.

This obliterated vessel (arrows) is surrounded by granulation tissue and then a necrotic rim with multinucleated giant cells. Inflamed connective tissue separates it from a necrotic nodule without a granulomatous rim at the upper right.

This "microabscess" with central PMNs resembles that seen in Wegener's granulomatosis. It may represent an angiitis around a very small vessel with a granulomatous response to it represented by the palisading histiocytes and multinucleated giant cells.

 

These pictures suggest that an angiitis causes inflammation that narrows the vessel and causes necrosis and granulomatous inflammation in the surrounding tissue. Ischemia may also contribute to the necrosis. This sequence of events has been proposed for the development of cutaneous rheumatoid nodules [1]. Further, these lesions are very similar to the angiitis and granulomatosis that develop in Wegener's granulomatosis.

Reference:

1. Sokoloff L, McCluskey R, Bunim J. Vascularity of the early subcutaneous nodule of rheumatoid arthritis. Arch Pathol 1953; 55:475-495.

Clinical summary Image 4

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