Wilms tumor and nephroblastomatosis are associated with syndromic conditions including hemihyperplasia. Hemihyperplasia is genetically heterogeneous and may be the result of genomic abnormalities seen in Beckwith–Wiedemann syndrome, mosaic chromosome or genomic abnormalities, or somatic point mutations. Somatic missense mutations affecting the PI3K-AKT-MTOR pathway result in segmental overgrowth and are present in numerous benign and malignant tumors. Here, we report a fourth patient with asymmetric overgrowth due to a somatic PIK3CA mutation who had nephroblastomatosis or Wilms tumor. Similar to two of three reported patients with a somatic PIK3CA mutation and renal tumors, he shared a PIK3CA mutation affecting codon 1047, presented at birth with asymmetric overgrowth, and had fibroadipose overgrowth. Codon 1047 is most commonly affected by somatic mutations in PIK3CA-related overgrowth spectrum (PROS). While the fibroadipose overgrowth phenotype appears to be common in individuals with PIK3CA mutations at codon 1047, individuals with a clinical diagnosis of Klippel–Trenaunay syndrome or isolated lymphatic malformation also had mutations affecting this amino acid. Screening for Wilms tumor in individuals with PROS-related hemihyperplasia may be considered and, until the natural history is fully elucidated in larger cohort studies, may follow guidelines for Beckwith–Wiedemann syndrome, or isolated hemihyperplasia. It is not known if the specific PIK3CA mutation, the mosaic distribution, or the clinical presentation affect the Wilms tumor or nephroblastomatosis risk in individuals with PROS.
Mutation in fibrinogen genes may lead to quantitative or qualitative disorders that result in bleeding, thrombosis or hepatic fibrinogen storage disease. Only three mutations in the fibrinogen γ gene have been identified that cause hepatic endoplasmic reticulum storage of mutant fibrinogen. To investigate the possibility of hepatic fibrinogen storage disease in a 4-year-old male with persistently elevated serum aminotransferases and preserved synthetic function except for a prolonged INR. After informed consent, liver and blood samples were obtained. Liver sections were examined by light microscopy, anti-fibrinogen immunolabelling and electron microscopy. Purified fibrinogen was analysed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis and reverse phase high performance liquid chromatography; DNA sequencing was performed using a BigDye Terminator (v. 3.1) cycle sequencing kit. Four-year-old male with persistently elevated transaminases with an INR 1.5 but otherwise normal synthetic function. Fibrinogen activity and thrombin clotting time were abnormal at 0.47 g/L and 46 s respectively. Hepatic histological examination revealed portal inflammatory infiltrates with bridging fibrosis. Clumped eosinophilic material was observed in hepatocytes that was immunoreactive to fibrinogen antisera. Ultrastructural examination showed cytoplasmic inclusions arrayed in fingerprint-like patterns. DNA sequence analysis revealed heterozygosity for a novel γ314Thr →Pro mutation (fibrinogen AI duPont) in the fibrinogen γ gene. Protein analyses showed normal patterns of Aα, Bβ and γ chains suggesting that the variant γ allele was not expressed in plasma fibrinogen. We describe only the fourth mutation to be identified, γ314Thr→Pro (fibrinogen AI duPont), giving rise to hypofibrinogenaemia and hepatic fibrinogen storage disease.
Since the original description of pathogenic germline DICER1 variation underlying PPB, the spectrum of extrapulmonary neoplasms known to be associated with DICER1 has continued to expand and now includes tumors of the ovary, thyroid, kidney, eye and brain among other sites. This report documents our experience with another manifestation: a primitive sarcoma that resembles PPB and DICER1 -associated sarcoma of the kidney. These tumors are distinguished by their unusual location in the peritoneal cavity, associated with visceral and/or parietal mesothelium. A total of seven cases were identified through pathology review in children presenting at a median age of 13 years (range 3 to 14 years). Primary sites of origin included the Fallopian tube (4 cases), serosal surface of the colon (one case), and pelvic sidewall (2 cases). One case had pathologic features of type I PPB, another type Ir (regressed) PPB and the remaining 5 had features of type II or III PPB with a mixed primitive sarcomatous pattern with or without cystic elements. All had a pathogenic DICER1 variation identified in germline and/or tumor DNA. PPB-like peritoneal tumors represent a newly described manifestation of DICER1 pathogenic variation whose pathologic features are also recapitulated in DICER1 -related renal sarcoma, cervical embryonal rhabdomyosarcoma, and some Sertoli-Leydig cell tumors with heterologous elements. Tumors arising from the Fallopian tube or elsewhere in the abdomen/pelvis, especially those with heterogeneous rhabdomyosarcomatous and/or cartilaginous differentiation, should prompt consideration of germline and tumor DICER1 testing.
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