Glomerular sparing (GS) is defined as a unique growth pattern in which
tumor cells replace the majority of renal tubes and overrun intact glomeruli. This phenomenon has been well recognized by pathologists as a typical infiltrative pattern and some studies suggested it was an independent risk factor. Here, we study the clinical, pathological, and immunohistochemical features of primary
kidney neoplasms with glomerular sparing pattern. We searched the archives of our pathology department for
nephrectomy specimens and reviewed all pathology reports from 2009-2013. We selected cases with
tumor and collected clinicopathological information, focusing on re-evaluation of cases with glomerular sparing pattern. To facilitate our study we performed immunohistochemical stains of PAX-8, p63, and InI-1 on selected cases. We selected a total of 204
nephrectomy cases in this study, including 163 cases of
renal cell carcinoma; 37 cases of urothelial
carcinoma; 4 cases from other categories (
Wilms tumor, primary
diffuse large B-cell lymphoma,
angiolipoma,
rhabdoid tumor). Finally, we identified 7 cases of primary kidney
tumors with glomerular sparing pattern: 2 cases of clear cell
renal cell carcinomas (ccRCC), 1 case of
collecting duct carcinoma, 2 cases of urothelial
carcinoma (UC), 1 case of
diffuse large B-cell lymphoma and 1 case of malignant
rhabdoid tumor. The primary kidney
tumors with glomerular sparing pattern are rare and incidence in our study is <4% (7/204). There is no specificity for any
tumor type, but more commonly seen in high grade UC rather than RCC. It can also be seen in rare
neoplasms such as
collecting duct carcinoma,
lymphoma and malignant
rhabdoid tumor. These GS cases need to be recognized as they are often associated with high grade, high stage, large
tumor size, and worse prognosis.