https://doi.org/10.1177/1066896919880263 International Journal of Surgical Pathology 1–6 © The Author(s) 2019 Article reuse guidelines: sagepub.com/journals-permissions DOI: 10.1177/1066896919880263 journals.sagepub.com/home/ijs Case Report Introduction Tubular adenoma of the urinary tract is extremely rare and has been documented in lower urinary tract predomi- nantly. 1 Adenoma of ureter is very uncommon, and reported cases include villous and tubulovillous adeno- mas. Similarly, adenocarcinoma of renal pelvis is also a rare tumor. In this article, we present 2 cases of adenocar- cinoma of upper urinary tract arising from tubular ade- noma with high-grade dysplasia having different clinical background. Case Report Case 1 A 44-year-old male patient presented with recurrent left flank pain and hematuria. Ultrasonography revealed con- tracted left kidney with stone at the pelvis. The right kid- ney was normal. A percutaneous nephrolithotomy was performed. Six months following this, the patient devel- oped pus discharging sinus at the percutaneous nephroli- thotomy site. At this time, renal function test was normal. Contrast-enhanced computed tomography scan revealed gross hydroureteronephrosis of left side with multiple ureteric hyperdense areas (mean attenuation = 70 HU). Left kidney measured 10.3 cm and revealed multiple hypodense areas (likely to be abscess), the largest measur- ing 3.1 × 2.1 cm, communicating with fistulous tract. The urinary bladder was normal. The patient was diagnosed as chronic pyelonephritis with nonfunctioning left kidney and underwent left nephroureterectomy. On gross examination, the kidney measured 11 × 7 × 4 cm, and external aspect was contracted and scarred. Ureter measured 15 cm in length and revealed 3 polypoi- dal growths projecting within the lumen, measuring from 1 to 1.5 cm (Figure 1A). Similar polypoidal growth was also seen in the pelviureteric junction. On opening the kid- ney, there was a large polypoidal growth filling the pelvis and infiltrating the renal parenchyma. In addition, there were multiple abscesses involving cortex and medulla of 880263IJS XX X 10.1177/1066896919880263International Journal of Surgical PathologyNambiyar et al research-article 2019 1 Postgraduate Institute of Medical Education and Research (PGIMER), Chandigarh, India Corresponding Author: Debajyoti Chatterjee, Department of Histopathology, Postgraduate Institute of Medical Education and Research (PGIMER), 5th Floor, Research Block A, Chandigarh 160012, India. Email: devchat1984@gmail.com Upper Urinary Tract Adenocarcinoma Arising in Tubular Adenoma—A Rare Entity: Report of 2 Cases and Review of Literature Kaniyappan Nambiyar, MD 1 , Tushar Pandey, MBBS 1 , Debajyoti Chatterjee, MD, DM 1 , Uma N. Saikia, MD 1 , and Ravimohan S. Mavuduru, MS, MCh 1 Abstract Tubular adenoma of the urinary tract is a recently recognized entity, and there is a paucity of clinicopathological information. We describe 2 rare cases of adenocarcinoma of upper urinary tract arising in the background of tubular adenoma with high-grade dysplasia. The first case was an extremely uncommon combination of multifocal tubular adenomas involving ureter and renal pelvis and adenocarcinoma of kidney in a patient with renal calculi. The second case was of adenocarcinoma of kidney arising from tubular adenoma of renal pelvis in the right moiety of horseshoe kidney. There was no microsatellite instability. These findings indicate, probably, an adenoma-carcinoma pathway is also followed in the urinary tract similar to the gastrointestinal tract. To the best of our knowledge, no such observations are reported in the English literature previously. Keywords urinary tract polyp, tubular adenoma, adenocarcinoma, horseshoe kidney, immunohistochemistry