Type 1 papillary renal cell carcinoma in a patient with schwannomatosis: Mosaic versus loss of SMARCB1 expression in respectively schwannoma and renal tumor cells

Genes, Chromosomes & Cancer
T J HulsebosUta Flucke

Abstract

In schwannomatosis, germline SMARCB1 or LZTR1 mutations predispose to the development of multiple benign schwannomas. Besides these, other tumors may occur in schwannomatosis patients. We present a 45-year-old male patient who developed multiple schwannomas and in addition a malignant type 1 papillary renal cell carcinoma (pRCC1). We identified a duplication of exon 7 of SMARCB1 on chromosome 22 in the constitutional DNA of the patient (c.796-2246_986 + 5250dup7686), resulting in the generation of a premature stop codon in the second exon 7 copy (p.Glu330*). The mutant SMARCB1 allele proved to be retained in three schwannomas and in the pRCC1 of the patient. Loss of heterozygosity analysis demonstrated partial loss of the wild-type SMARCB1 allele containing chromosome 22, suggesting loss of that chromosome in only a subset of tumor cells, in all four tumors. Immunohistochemical staining with a SMARCB1 antibody revealed a mosaic SMARCB1 expression pattern in the three benign schwannomas, but absence of expression in the malignant tumor cells of the pRCC1. To our knowledge, this difference in SMARCB1 protein expression has not been reported before. We conclude that a germline SMARCB1 mutation may predispose to the development of ...Continue Reading

References

Feb 21, 2008·Journal of Medical Genetics·K D HadfieldD G R Evans
Oct 12, 2010·Journal of Medical Genetics·I ChristiaansT J M Hulsebos
Nov 26, 2010·Pediatric Blood & Cancer·Katherine W EatonJaclyn A Biegel
Feb 13, 2013·American Journal of Medical Genetics. Part a·Scott R PlotkinMarco Giovannini
Feb 15, 2014·The American Journal of Surgical Pathology·Theo J M HulsebosUta Flucke
Dec 7, 2014·Neurology·Miriam J SmithD Gareth Evans

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