Distal Tubular Hyperplasia: A Proposal for a Unique Form of Renal Tubular Proliferation Distinct From Papillary Adenoma.

We identified an unusual pattern of renal tubular proliferation associated with chronic renal disease, found in 23 patients, diffusely (n=12), or focally (n=11). Incidence was 5% of end-stage renal disease kidneys from one institution (8/177) and 7/23 patients with acquired cystic kidney disease-associated renal cell carcinoma from another. Most (19 patients) had 1 or more neoplasms including papillary (n=9), acquired cystic kidney disease (n=8), clear cell (n=4), or clear cell papillary (n=3) renal cell carcinoma.

Pseudoangiosarcomatous urothelial carcinoma of the urinary bladder.

The pseudoangiosarcomatous pattern has been described mostly in cutaneous and some visceral squamous cell carcinomas and is unique for its striking morphologic resemblance to angiosarcoma. Herein, we describe the clinicopathologic features of 7 pseudoangiosarcomatous urothelial carcinomas that occurred in the urinary bladder. The patients included 6 men and 1 woman ranging in age from 47 to 87 years (median 70 y).

The utility of PAX-2 and renal cell carcinoma marker immunohistochemistry in distinguishing papillary renal cell carcinoma from nonrenal cell neoplasms with papillary features.

PAX-2, a homeogene expressed during kidney development, has been studied as a marker of renal origin in both primary and metastatic clear cell renal cell carcinoma (RCC), but not in papillary neoplasms or in comparison with RCC marker (RCCma). We studied immunohistochemical expression of PAX-2 and RCCma in 24 papillary RCC (PRCC) and 66 nonrenal cell papillary neoplasms (NRCPN) from a variety of organs. Of the PRCC, 16/24 (67%) were positive for PAX-2; 23/24 (96%) were positive for RCCma.