De novo germline TP53 mutation presenting with synchronous malignancies of the central nervous system

Immune Checkpoint Inhibition as Single Therapy for Synchronous Cancers Exhibiting Hypermutation: An IRRDC Study

Two targets with one arrow: #Immunotherapy as single treatment for synchronous RRD #glioblastoma and #metastatic cancers.

Contribution of de novo and mosaic TP53 mutations to Li-Fraumeni syndrome

Background

Development of tumours such as adrenocortical carcinomas (ACC), choroid plexus tumours (CPT) or female breast cancers before age 31 or multiple primary cancers belonging to the Li-Fraumeni (LFS) spectrum is, independently of the familial history, highly suggestive of a germline TP53 mutation. The aim of this study was to determine the contribution of de novo and mosaic mutations to LFS.

Methods and results

Among 328 unrelated patients harbouring a germline TP53 mutation identified by Sanger sequencing and/or QMPSF, we could show that the mutations had occurred de novo in 40 cases, without detectable parental age effect. Sanger sequencing revealed two mosaic mutations in a child with ACC and in an unaffected father of a child with medulloblastoma. Re-analysis of blood DNA by next-generation sequencing, performed at a depth above 500X, from 108 patients suggestive of LFS without detectable TP53 mutations, allowed us to identify 6 additional cases of mosaic TP53 mutations, in 2/49 children with ACC, 2/21 children with CPT, in 1/31 women with breast cancer before age 31 and in a patient who developed an osteosarcoma at age 12, a breast carcinoma and a breast sarcoma at age 35.

Conclusions

This study performed on a large series of TP53 mutation carriers allows estimating the contribution to LFS of de novo mutations to at least 14% (48/336) and suggests that approximately one-fifth of these de novo mutations occur during embryonic development. Considering the medical impact of TP53 mutation identification, medical laboratories in charge of TP53 testing should ensure the detection of mosaic mutations.

A Comprehensive Review of Pediatric Tumors and Associated Cancer Predisposition Syndromes

An understanding of the role of inherited cancer predisposition syndromes in pediatric tumor diagnoses continues to develop as more information is learned through the application of genomic technology. Identifying patients and their relatives at an increased risk for developing cancer is an important step in the care of this patient population. The purpose of this review is to highlight various tumor types that arise in the pediatric population and the cancer predisposition syndromes associated with those tumors. The review serves as a guide for recognizing genes and conditions to consider when a pediatric cancer referral presents to the genetics clinic.

Synchronous glioblastoma and medulloblastoma in a child with mismatch repair mutation

Synchronous primary malignant brain tumors are rare. We present a 5-year-old boy with synchronous glioblastoma and medulloblastoma. Both tumor samples had positive p53 stain and loss of PMS2 and MLH1 stains. The child had multiple café au lait spots and a significant family history of cancer. After subtotal resection of both tumors, he received craniospinal radiation with concomitant temozolomide followed by chemotherapy, alternating cycles of cisplatin/lomustine/vincristine with temozolomide. Then, he started maintenance treatment with cis-retinoic acid (100 mg/m(2)/day for 21 days). He remained asymptomatic for 34 months despite a follow-up brain MRI consistent with glioblastoma relapse 9 months before his death. Cis-retinoic acid may have contributed to prolong survival in this child with a probable biallelic mismatch repair syndrome.

A novel TP53 somatic mutation involved in the pathogenesis of pediatric choroid plexus carcinoma

Background

Choroid plexus carcinoma (CPC) is an uncommon, aggressive, malignant, central nervous system neoplasm that typically occurs in children, presenting with the signs and symptoms of intracranial hypertension and cerebrospinal fluid obstruction.

Case Report

We report the case of a 2.5-year-old girl with CPC. The tumor was subtotally removed by microsurgery, followed by gamma knife radiosurgery for the residual lesion. H&E staining indicated that this was a rare case of CPC. Neuropathological studies, assayed by immunohistochemical staining, showed that the tumor sample was positive to antibodies against S-100, CgA, AE1/AE3 (cytokeratin), Ki-67, INI1 and TP53, and was negative to antibodies against Nestin, GFAP, CD133, EMA and AFP. Moreover, stainings for transthyretin and vimentin were focally positive. Interestingly, direct DNA sequencing of the paraffin-embedded tumor sample identified a novel R248Q mutation in the TP53 gene. In contrast to previous reports suggesting that TP53 germline mutations were associated with the pathogenesis of CPC, here we provide a rare case of CPC with TP53 somatic mutation, as evidence that the peritumoral tissue possesses the non-mutant TP53 allele.

Conclusions

Our finding suggests that TP53 somatic mutations, in addition to its germline mutations, may also be involved in the pathogenesis of pediatric CPC.