SEER Inquiry System - Question 20160048 Details

The pathology diagnosis reads: Diagnosis Right Kidney, Laparoscopic Nephrectomy: 

-Renal Cell Neoplasm of Oncocytosis (pT1a, pNX See Comment and Template). 

-Surgical margins free of tumor.

Kidney, right, nephrectomy:

Tumor histologic type: Renal cell neoplasms of oncocytosis (see Note)

Sarcomatoid features (%) Not identified

Tumor size: 4 cm (greatest dimension largest tumor)

Other dimensions: 2.7 x 2.5 cm

Macroscopic extent of tumor: Limited to kidney

Focality: Multifocal

Number of tumors: 11 grossly visible, range 0.2 4 cm

Fuhrman grade: 2 of 4

Microscopic extent of tumor:

Perinephric fat invasion: Not identified

Renal sinus invasion: Not identified

Other: N/A

Renal vein involvement: Not identified

Adrenal gland present: No

Involved by tumor: N/A

Direct invasion or metastasis: N/A

Cancer at resection margin: Not identified

Location(s): N/A

Pathologic findings in nonneoplastic kidney: Multiple collections of oncocytic cells

Hilar lymph nodes present: No

Number of involved/number present: N/A

"Thank you for sending this fascinating case. In reviewing the H&E-stained slides, we recognize that multiple lesions of varying sizes are present within the specimen, some with features of oncocytoma, some with those of chromophobe RCC, and yet others with features of both. The immunohistochemical studies for CK7 performed at your institution serve to highlight this point with "mass #1" showing focal single cell staining typical of oncocytoma and "mass #2" showing a patchy and confluent staining pattern typical of chromophobe RCC. This second mass was also positive with special stain for Hales colloidal iron. As mentioned, the morphology varies somewhat in each tumor, however, every single mass is comprised of cells with eosinophilic (pink to bright red) cytopolasm. Some tumors show more tightly nested or sheet like growth, others are more tubular or microcystic. Another important feature, present on slides of renal cortex are microscopic tumorlets seemingly emanating from eosinophilic tubules. This finding, along with the presence of numerous oncocytic neoplasms is supportive of the above diagnosis. The absence of clinical features to suggest Birt-Hogg-Dube syndrome is noted. Although these tumors are not recognized in the current classification of renal tumors, we regard these neoplasms as being a distinct entity, unrelated to both oncocytoma and chromophobe renal cell carcinoma, and have applied the designation "renal tumor of oncocytosis" to such lesions (Gobbo S, et al. Renal cell neoplasms of oncocytosis have distinct morphologic, immunohistochemical, and cytogenetic profiles. Am J Surg Patholl 34:620-626, 2010). We concur that the expected behavior in these cases is one of indolence."