View source for CRP-21

'''CRP-21'''
==Clinical History==
The patient is an 80 year old male. Admitted with shortness of breath and generalized weakness. Microscopic hematuria was discovered during his workup, and subsequently a left renal mass was identified. He underwent left nephrectomy and pathologic examination revealed papillary renal cell carcinoma. On admission his BUN and creatinine were 16 and 1.3. However, the day after surgery they had risen to 21 and 1.6, 4 days later they were 29 and 3.6, and 7 days after that they were 53 and 6.1. ANCA serology negative. ANA positive.

==Gross Description==
Received from an outside Medical Center are five paraffin blocks, five slides stained with H&E, three slides stained with GMS, and one vial of Carson's fixative with several small fragments of tissue.

==Pathology==
===Case CRP-021 H&E===
<peir-vm>specialcrp/CRP-021_HE</peir-vm>
===Case CRP-021 PASH===
<peir-vm>specialcrp/CRP-021_PASH</peir-vm>
===Case CRP-021 Silver===
<peir-vm>specialcrp/CRP-021_Silver</peir-vm>
===Case CRP-021 Trichrome===
<peir-vm>specialcrp/CRP-021_Trichrome</peir-vm>

<div class="usermessage mw-customtoggle-diagnosis" style="cursor:pointer"> Microscopic Description, Immunofluorescence, and Electron Microscopy</div>
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==Microscopic Description==
===Light Microscopy===
One of the blocks was used to prepare additional sections, which were cut at two microns and stained with H&E, PASH, trichrome and Jones' methenamine silver. This sections contain over 100 glomeruli. Two glomeruli with segmental necrotizing lesions are identified, but the remaining glomeruli show minimal mesangial expansion without proliferation. The glomerular basement membranes are unremarkable with the silver stain. PASH and trichrome stains show very mild focal interstitial fibrosis and tubular atrophy in the most superficial cortex, but there is no significant interstitial fibrosis in the deeper cortex. The most striking feature in the section is the presence of numerous small arteries with necrotizing granulomatous inflammation. This is transmural arteritis with essentially complete destruction of the arterial wall. The inflammatory infiltrate consists of macrophages, lymphocytes and numerous eosinophils with occasional multinucleated giant cells. No thrombi are identified. The larger arteries show mild intimal fibrosis, but they are otherwise unremarkable.

===Immunofluorescence===
Sections were cut from the paraffin block, treated with Pronase digestion, and then stained with the usual panel of antibodies. There is no glomerular staining for IgG, IgM, IgA, C1q, C3, albumin or light chains. There is no staining in the vessels or tubular basement membranes.

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<spoiler text="Diagnosis and Comments">
Kidney, left nephrectomy: Pauci-immune, necrotizing granulomatous arteritis and focal necrotizing glomerulonephritis.

This is a very unusual case. It is striking that the vascular lesion is much more widespread than the glomerular lesion, which is quite mild and focal. A positive ANCA would have helped confirm the category of disease, but even with a negative ANCA I still consider it pauci-immune small vessel

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