Renal cell carcinoma in children and adolescents: a retrospective study of a French-Italian series of 93 cases.

AIMS: Renal cell carcinomas (RCCs) represent 2-5% of kidney malignancies in children and adolescents. Appropriate diagnostic and classification are crucial for the correct management of the patients and in order to avoid inappropriate pre-operative chemotherapy, which is usually recommended if a Wilms' tumour is suspected. METHODS AND RESULTS: A French-Italian series of 93 renal cell carcinomas collected from 1990 to 2019 in patients aged less than 18 years was reclassified according to the 2016 World Health Organization (WHO) classification and the latest literature. TFE3 and TFEB fluorescence in-situ hybridisation (FISH) analyses and a panel of immunohistochemical stains were applied. The median age at diagnosis was 11 years (range = 9 months-17 years). MiT family (MiTF) translocation RCCs accounted for 52% of the tumours, followed by papillary (20%) and unclassified RCCs (13%). Other subtypes, such as SDHB-deficient and fumarate hydratase-deficient RCCs, represented 1-3% of the cases. We also described a case of ALK-rearranged RCC with a metanephric adenoma-like morphology. CONCLUSION: A precise histological diagnosis is mandatory, as targeted therapy could be applied for some RCC subtypes, i.e. MiTF-translocation and ALK-translocation RCC. Moreover, some RCC subtypes may be associated with a predisposition syndrome that will impact patients' and family's management and genetic counselling. A precise RCC subtype is also mandatory for the clinical management of the patients and inclusion in new prospective clinical trials.

Deciphering intra-tumor heterogeneity of lung adenocarcinoma confirms that dominant, branching, and private gene mutations occur within individual tumor nodules.

While pulmonary adenocarcinoma (ADC) is morphologically heterogeneous, little is known about intra-tumor gene mutation heterogeneity (ITH). We therefore subjected 20 ADC nodules, 5 mutated for EGFR and 5 for KRAS, 5 with an ALK translocation, and 5 wild type (WT) for these alterations, to unsupervised next-generation sequencing of tumor regions from diverse architectural patterns. When 2 or more different gene mutations were found in a single tumor, this fulfilled the criteria for ITH. In the 84 studied tumor regions with diverse architecture, 71 gene mutations and 34 WT profiles were found. ITH was observed in 9/15 (60 %) ADC, 3 with an EGFR, 3 with a KRAS, and 3 with an ALK aberration, as reflected in 5, 6, and 9 additional mutations, respectively, detected in these tumors. EGFR mutations were observed in 21/22 and KRAS mutations in 18/22 tumor regions, suggesting that they appear early and have a driver role (dominant or trunk mutations). Branching mutations (in EZH2, PIK3CA, TP53, and EGFR exon 18) occurred in two or more regions, while private mutations (in ABL1, ALK, BRAF, HER2, KDR, LKB1, PTEN, MET, SMAD4, SMARCB1, and SRC) were confined to unique tumor samples of individual lesions, suggesting that they occurred later on during tumor progression. Patients with a tumor showing branching mutations ran a worse clinical course, independent of confounding factors. We conclude that in ADC, ITH exists in a pattern suggesting spatial and temporal hierarchy with dominant, branching, and private mutations. This is consistent with diverse intra-tumor clonal evolution, which has potential implications for patient prognosis or development of secondary therapy resistance.

Complex karyotype in a case of cutaneous lymphangiosarcoma associated with chronic lymphedema of the lower limb.

Lymphangiosarcoma is a rare malignant neoplasm of endothelial cells. The term is used to describe an angiosarcoma associated with chronic lymphedema. The skin of the head and neck region is the most common site of origin. Rather few cytogenetic studies on lymphangiosarcoma are reported in the literature. We here describe a case of an 87-year-old woman, with a history of recurring lymphangitis and with an ulcerated nodular lesion of the leg. The histological diagnosis was a malignant neoplasm of vascular origin, with the morphological and immunohistochemical features of a lymphangiosarcoma. A series of antibodies (CD31, CD34, vimentin, podoplanin and HHV-8), conventional and molecular cytogenetic and Spectral Karyotyping (SKY-FISH) analyses were used to study this case. The immunohistochemical evaluation revealed that the neoplasm was positive for vimentin, CD31, CD34 and podoplanin and negative for HHV-8. The proliferation rate (Ki-67) was about 70%. Karyotype was defined using conventional cytogenetic and SKY-FISH. In addition, high-level of amplification was observed with MYC split signal probe. The morphological and immunohistochemical evaluations supported the diagnosis of lymphangiosarcoma. Moreover, the cytogenetic and molecular findings contributed towards accurately defining the karyotypic aberrations of this rare sarcoma.