102. Using cytogenomics to distinguish two types of renal cell carcinoma in a composite or collision tumor

Aly Abdelkareem

Lauren Wainman

Lauren is currently a postdoctoral fellow in the Clinical Genomics and Advanced Technologies Laboratory in the Department of Pathology and Laboratory Medicine at Dartmouth-Hitchcock Medical Center. Her clinical responsibilities include somatic variant classification and interpretation, running select clinical assays, and evaluation/validation of new clinical assays. Her research responsibilities include designing experiments, writing IRB proposals, obtaining clinical samples and obtaining data for studies in hematology, metagenomics, and somatic whole exome sequencing.

Before coming to Dartmouth-Hitchcock Medical Center, Lauren obtained her PhD in Molecular and Cell Biology from University of Connecticut in 2022. During her PhD Lauren applied nascent RNA sequencing methods to examine enhancer function in diseases such as Chronic Lymphocytic Leukemia and Cutaneous T-cell Lymphoma.


Lauren Wainman, Samantha Stephen, Joel Lefferts, Jason Pettus

Dartmouth Hitchcock Medical Center, Lebanon, NH, United States

The coexistence of phenotypically and genotypically distinct tumors within a single lesion is rare and may indicate a collision (two separate origins) or composite (common origin) tumor. This phenomenon in the kidneys may include benign and malignant tumor types including metastasis from elsewhere in the body. Collision and composite tumors of two different renal cell carcinoma subtypes is exceedingly rare. Here we present a case of a 46-year-old male patient who underwent a partial nephrectomy due to a renal mass identified by CT scan. Histopathology and immunohistochemistry revealed classic clear cell renal cell carcinoma (ccRCC) morphology with multiple foci of papillary renal cell carcinoma (pRCC) near the periphery. Chromosome microarray performed separately on the two distinct regions revealed copy number losses in the ccRCC involving 3p, proximal 3q, distal 6q and 21q. The pRCC shared the copy number loss of 21q, but had a distinct set of findings including copy neutral loss of heterozygosity of chr6, copy number gains of chromosomes 7, 12, 17 and loss of chrY. These distinct cytogenomic findings are consistent with recurrent findings in ccRCC and pRCC, respectively. The 21q copy number loss in both tumors may suggest a single precursor clone from which both tumors originated, but this shared finding could also be the result of two separate chr21 loss events in the development of the two tumors. Meticulous examination of histologic features and molecular testing can shed light on the possible biological and molecular mechanisms responsible for the presence of collision and composite tumors.