Histologic Changes--Angiitis

In the vicinity of the nodules, there was evidence of an angiitis involving muscular arteries and small veins.

This muscular artery shows a segmental, necrotizing angiitis with inflammatory cells, including PMNs, infiltrating the thickened intima and the media of the left upper quadrant. The lumen is considerably narrowed. There is an infiltrate of lymphocytes and plasma cells in the surrounding tissue.

This vein shows evidence of old intimal fibrous thickening and narrowing. In addition, there is an acute inflammatory infiltrate of mostly PMNs in the intima and the inner wall. Again, there are chronic inflammatory cells in the surrounding tissue.

This muscular artery to the right of an airway shows eccentric narrowing of the lumen by pale-staining, recent, intimal proliferation (upper portion of wall). It also shows some adventitial fibrosis. Although no inflammation is present, in this setting these changes are probably related to a previous angiitis.

This elastic van Gieson stain shows a muscular artery (note inner and outer elastic layers), which shows marked intimal fibrosis that leaves only 3 slit-like channels. Although the channels suggest recanalization of a thrombus, they may represent channels left by irregular intimal thickening. The adventitia is thickened and fibrotic.

Which of the diagnoses suggested by the HRCT are still possible? Answer

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Answer:

The differential diagnosis of the HRCT includes pyogenic bacterial infection, including septic emboli; tuberculosis; non-tuberculous mycobacterial infection; fungal (including pneumocystis) infection, metastatic neoplasm, sarcoidosis, Wegener's granulomatosis, and pleuronodular disease of rheumatoid arthritis.

Diagnoses that still need to be considered are pyogenic bacterial infection with a septic angiitis, tuberculous and non-tuberculous mycobacterial infections, fungal infection, Wegener's granulomatosis, and pleuronodular disease of rheumatoid arthritis. There was no evidence of neoplasm or non-necrotizing granulomas of sarcoidosis.

Further studies included a tissue Gram stain, acid fast stain, the Gomori methenamine silver stain for fungi, and cultures of the lesions, all of which were negative for organisms, leaving Wegener's granulomatosis and pleuronodular disease of rheumatoid arthritis still under consideration.

Further lesions are illustrated on the following pages.

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