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Polyomavirus associated nephropathy (PyVAN) continues to be a burden in renal transplantation leading to allograft insufficiency or graft failure. A presumptive diagnosis of PyVAN is made based on the presence of BK polyomavirus in patients' plasma; however, kidney biopsy remains the gold standard to establish a definitive diagnosis. The Banff Working Group on PyVAN proposed a novel classification of definitive PyVAN based on polyomavirus replication/load level and the extent of interstitial fibrosis. The aim of our study was to test the newly defined classes of PyVAN using independent cohorts of 124 kidney transplant patients with PyVAN with respect to the initial presentation and outcome, and to compare our analysis to that previously reported. Detailed analysis of our cohort revealed that the proposed classification of PyVAN did not stratify or identify patients at increased risk of allograft failure. Specifically, while class 3 was associated with the worst prognosis, there was no significant difference between the outcomes in classes 1 and 2. We also found that the timing post-transplantation and inflammation in areas of interstitial fibrosis and tubular atrophy might be additional factors contributing to an unfavorable allograft outcome in patients with PyVAN.

Interstitial eosinophilic aggregates (IEA) in renal biopsies often suggest allergic tubulointerstitial nephritis, yet clear associations with drug reactions are often difficult to establish. IEA are also encountered in diabetic nephropathy (DN) and thought to be attributed to medication exposure.Native medical kidney biopsies performed at the University of Washington Medical Center were reviewed, including DN (n = 64), IgA nephropathy (IgAN, n = 28), membranous nephropathy (MN, n = 14), focal and segmental glomerulosclerosis (FSGS, n = 27) and membranoproliferative glomerulonephritis (MPGN, n = 28). IEA were defined as ≥5 eosinophils per high power field. The severity of interstitial fibrosis and tubular atrophy (IFTA) was scored semi-quantitatively as minimal, mild, moderate or severe.IEA were remarkably more prevalent in DN (41%), when compared with IgAN (7%, P = 0.001), MN (8%, P = 0.017) or MPGN (14%, P = 0.013), but not FSGS (26%, P = 0.18). In DN cases, univariate analysis revealed that IEA were associated with greater IFTA severity, but not with the percentage of glomerulosclerosis, mesangial expansion, history of drug allergy, number of prescribed medications or particular class of medications (antibiotics, NSAIDs, aspirin, thiazide, loop diuretics, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, calcium channel blockers, beta blockers, insulin, sulfonylurea, metformin or allopurinol). Multivariate analysis showed that the severity of IFTA was the only significant predictor for IEA (P0.01) after stepwise adjustment for age, number of medications, drug allergy, diabetes type, % global glomerulosclerosis and mesangial expansion.Our study shows that IEA are more common in DN, when compared with other types of glomerulopathy. In DN, IEA are associated with the severity of IFTA but not with prescribed medications or clinical history of allergy. This suggests that in DN IEA are often associated with chronic tubulointerstitial injury and are not diagnostic of an allergic interstitial nephritis.

Chondromatous hamartomas are the most common benign lung tumors and the third most common pulmonary nodule. Histologically, they are characteristically composed of hyaline cartilage mixed with fibromyxoid stroma and adipose tissue surrounded by epithelial cells. We report the case of a healthy, 60-year-old woman with an incidentally discovered chondromatous hamartoma that was thorascopically excised. Her pulmonary hamartoma was predominantly cartilaginous, which only occurs in 1% of hamartomas.