cow-2023-03

1. What is the correct diagnosis?
a. Multilocular cystic neoplasm of low malignant potential
b. FH-deficient renal cell carcinoma
c. Oncocytoma
d. Tubulocystic renal cell carcinoma

2. Which of the following genes may be mutated in tubulocystic renal cell carcinoma?
a. ABL1
b. WT1
c. TCEB1
d. PTEN

1. d. Tubulocystic renal cell carcinoma
2. a. ABL1

Tubulocystic renal cell carcinoma

Tubulocystic renal cell carcinomas (TC RCC) are not common, with the majority being an incidental finding, typically affecting males (7:1 M:F), with a mean age of 60. Grossly, tumors have a spongy bubble wrap appearance and cysts of varying sizes containing serous fluid. Histology shows small to intermediate-sized cystically dilated tubules that are evenly dispersed in fibrotic stroma. Cysts are lined by a single layer of flat, hobnail, or cuboidal to columnar cells with abundant eosinophilic cytoplasm, large nuclei, and prominent nucleoli. The majority are positive for CK7, CD10, and AMACR, while FH is intact. Molecular abnormalities include an overexpression of genes related to amino acid metabolism and the cell cycle. Mutations in ABL proto-oncogene 1, nonreceptor tyrosine kinase (ABL1), and platelet-derived growth factor alpha (PDGFRA) are found in greater than 60% of tumors. Other abnormalities described include loss of chromosomes 9, 15, 18, and Y, gains of chromosome 17, or copy neutral loss of heterozygosity in 6p22.1.

1. Amin & Tickoo. (2016). Tubulocystic Carcinoma. In Diagnostic pathology: Genitourinary (pp. 124–127), Elsevier.
2. Bhullar, J. S., Bindroo, S., Varshney, N., & Mittal, V. (2014). Tubulocystic renal cell carcinoma: A rare renal tumor. Journal of Kidney Cancer and VHL, 1(5), 56–62. https://doi.org/10.15586/jkcvhl.2014.13
3. Sarungbam, J., Mehra, R., Tomlins, S. A., Smith, S. C., Jayakumaran, G., Al-Ahmadie, H., Gopalan, A., Sirintrapun, S. J., Fine, S. W., Zhang, Y., Amin, M. B., Reuter, V. E., Chen, Y.-B., & Tickoo, S. K. (2019). Tubulocystic renal cell carcinoma: A distinct clinicopathologic entity with a characteristic genomic profile. Modern Pathology, 32(5), 701–709. https://doi.org/10.1038/s41379-018-0185-5
4. Eble, J. N., Argani, P., Grignon, D. J., & Cheng, L. (2022). Renal Tumors of Adults. In Tumors of the kidney, bladder, and related urinary structures (pp. 165–169). American Registry of Pathology.

Mckinley Smith, Dr. Nicholas Baniak
University of Saskatchewan, College of Medicine. Department of Pathology and Laboratory Medicine

Kidney

Tubulocystic renal cell carcinoma; kidney