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Archive: July 2017

IgAN and Acute Tubular Injury with Legionella

Acute kidney injury in the setting of Legionella pneumonia. This biopsy is a middle-aged person with Legionella pneumonia who developed acute kidney injury. Early in the hospitalization, the baseline creatinine was 1.0 mg/dl. However, the creatinine rose to 6.5 over 5 days and Nephrology was consulted. Urinalysis showed microscopic hematuria and 2+ proteinuria. The creatinine increased to 7.5 and a biopsy was done. Serologic studies were ordered and were pending at the time of biopsy. The images provided show a combination of acute tubular injury (Image 1), mild mesangial matrix expansion (Image 2) and mesangial IgA deposits (Image 3). While...

2,8-Dihydroxyadenuria

Adenine phosphoribosyltransferase (APRT) deficiency results from an autosomal recessive enzyme defect of purine metabolism and leads to 2,8-dihydroxyadenine (2,8-DHA) crystalline nephropathy. The clinical presentation of this often misdiagnosed disease is widely variable among patients homozygous for APRT mutations, ranging from asymptomatic in some to reddish-brown diaper stains in infants to recurrent nephrolithiasis, and even CKD in the absence of nephrolithiasis. 2,8-DHA nephropathy has also been reported to recur in the renal allograft resulting in rapid allograft failure. Prompt and accurate diagnosis of this disorder is important so that treatment through pharmacologic inhibition of xanthine dehydrogenase can be initiated. The morphologic findings...

Extramedullary Hematopoiesis

This renal biopsy shows extramedullary hematopoiesis (EMH), which is the presence of hematopoietic elements (erythroid, myeloid, and/or megakaryocytic) found outside of the bone marrow. The larger circle contains mostly erythroid precursors and the arrow identifies an immature megakaryocyte. Generally, the histologic differential diagnosis includes acute interstitial nephritis (erythroid precursors may be confused with mature inactive lymphocytes) and even some types of lymphoma (megakaryocytes may resemble atypical or malignant lymphoid cells). In difficult cases, lineage-specific immunohistochemical stains can be used to confirm the presence of hematopoietic cells. Recognizing EMH is important because it often signifies impaired bone marrow function due to...

Pushing Glass (July 25, 2017)

The patient is a 64-year-old female who presents with 4.5 grams of proteinuria, hematuria, and a creatinine of 1.5. She has a history of hypertension and coronary artery disease. What is the best diagnosis? A. Arterionephrosclerosis B. Focal Segmental Glomerulosclerosis C. Amyloidosis D. Fibrillary Glomerulonephritis The best answer is C: Amyloidosis. The biopsy, at first glance, looks like a subcapsular scar with diffuse global glomerulosclerosis. In this setting, arterionephrosclerosis would provide a good explanation for this distribution of fibrosis especially with the severe arteriosclerosis seen in the vessel. FSGS is also a consideration and can produce segmental scars with extensive...

Caseating Granuloma

Incidental findings on renal biopsies are not uncommon. The presented image shows a caseating granuloma within the renal medulla of a diabetic patient without known history of infection. The lesion shows central necrosis surrounded by palisading histiocytes and scattered lymphocytes. Caseating granulomata are highly suspicious for mycobacterial or fungal infections. While AFB, Auramine-Rhodamine and GMS stains are negative in this case, due to the relative insensitivity of these stains, ruling out an infection clinically is warranted. In those cases with non-caseating granulomata, the differential diagnosis would expand to include drug reactions, sarcoidosis and other autoimmune disorders. In such cases, performing...

Diagnose This! (July 24, 2017)

What is your diagnosis?       ​   ​ ​   ​   ​ ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​ ​   ​ ​   ​ ​   ​ ​     ​   ​  ...

Arkanines: Abby

Meet Abby! She's a 13-week-old Airedale Terrier. She loves squeaky toys and naps, but does not enjoy being woken up from said naps. She belongs to Christa, who is one of the cheerful voices you hear answer the phone here at Arkana.

Vascular Endothelial Growth Factor

The biopsy shown here is from a seven-year-old female with nephrotic syndrome. Her serum Cr was increased to 0.9 mg/dl and her urine protein/creatinine ratio was 7. She was s/p nephrectomy for renal cell carcinoma and had been treated with bevacizumab for six months prior to the biopsy. Serum C3 and C4 levels were normal and her platelet count was also normal. On biopsy, glomeruli show extensive basement membrane duplication and segmental hyalinosis of the glomerular tuft (arrow). These glomerular changes are characteristic of VEGF inhibitor-associated glomerulopathy. There is evidence to suggest that VEGF production by podocytes is required for...

Acute Pyelonephritis

The renal biopsy image shows features characteristic of acute pyelonephritis. There is a neutrophil-rich interstitial inflammatory infiltrate and evidence of acute tubular injury. Some tubular lumens are filled with neutrophils (arrow), and in some areas, neutrophils encircle the outer aspect of the tubules between the tubular basement membrane and the interstitium (arrowhead). In some cases, micro abscesses may even form (not shown). In most cases of ascending infection, large vessels and glomeruli are uninvolved. If arteritis or neutrophilic infiltrates involve glomeruli, the possibility of a hematogenous infectious source should be considered.