FGFR1 gene fusions in a subset of pediatric mesenchymal tumors: Expanding the genetic spectrum of tumors sharing histologic overlap with infantile fibrosarcoma and "NTRK-rearranged" spindle cell neoplasms.

As the classification of kinase-driven spindle cell tumors continues to evolve, we describe the first series of pediatric mesenchymal tumors harboring FGFR1 gene fusions that share histologic overlap with infantile fibrosarcoma and "NTRK-rearranged" spindle cell neoplasms. Herein, we present three cases of FGFR1-rearranged pediatric mesenchymal tumors, including one case with FGFR1::PARD6B gene fusion and two cases with FGFR1::EBF2 gene fusion. The tumors involved infants ranging from 3 to 9 months in age with a male-to-female ratio of 2:1. All tumors involved the deep soft tissue of the gluteal, pelvic, or perirectal region. Histologically, the tumors comprised a cellular spindle cell neoplasm with primitive stellate cells, focal myxoid stroma, focal epithelioid features, no necrosis, and occasional mitotic figures (2-6 per 10 high-power field). By immunohistochemistry, the neoplastic cells focally expressed CD34 but lacked expression of S100 protein, SMA, desmin, myogenin, MyoD1, pan-TRK, and ALK. These three cases, including a case with long-term clinical follow-up, demonstrate that FGFR1 fusions occur in a subset of newly described pediatric kinase-driven mesenchymal tumors with locally aggressive behavior. Importantly, knowledge of these genetic alterations in this spectrum of pediatric tumors is key for diagnostic and targeted therapeutic purposes.

Audit of waiting time-to-treatment of atypical endometrial hyperplasia.

BACKGROUND: Atypical endometrial hyperplasia (AEH) is the precursor lesion in endometrial carcinoma, the most common gynaecological malignancy in New Zealand, with inequities in disease burden and outcome for Maori and Pacific women. AIMS: In women diagnosed with AEH at two hospitals, to audit five standards of care for surgical management and time-to-treatment, and identify variation in care by ethnicity and other factors. MATERIALS AND METHODS: Demographic, referral, diagnostic and treatment characteristics were collected for women with a new AEH diagnosis between 1/1/2019 and 31/12/2020. Surgical management and time-to-treatment were audited against Royal College of Obstetricians and Gynaecologists and New Zealand Ministry of Health Faster Cancer Treatment recommendations. RESULTS: Of 124 participants, 60% were Pacific, 86% premenopausal, and 80% had obesity. For 55 women managed surgically, surgical standards of care were met. There were delays between referral, diagnosis and treatment - only 18% and 56% of women met the 62-day (referral to treatment) and 31-day (decision-to-treat to treatment) targets, respectively. Wait times were prolonged for women who had dilation and curettage (vs pipelle), magnetic resonance imaging (MRI) (vs no MRI), and surgery (vs medical management). Ethnic disparities were not identified for any standard. DISCUSSION: Delays to treatment were found throughout women's journeys. Hospital services can streamline their clinical pathways for women referred for abnormal uterine bleeding, flagging obesity as a high suspicion for cancer indicator, increasing access to endometrial sampling in primary care and establishing 'one-stop-shop' outpatient assessment with empiric initiation of intrauterine progestogen.

USP6 gene rearrangement in nodular fasciitis and histological mimics.

AIMS: Nodular fasciitis is known to be a benign mimic of sarcoma, both clinically and histologically. Accurate diagnosis, particularly on small biopsies, remains a challenge, as the morphology can be varied and the immunophenotype is essentially non-specific. Recently, rearrangement of the ubiquitin-specific protease 6 (USP6) gene has been reported as a recurrent and specific finding in nodular fasciitis. The aim of this this study was to evaluate the diagnostic utility of USP6 fluorescence in-situ hybridization (FISH) analysis in a subset of spindle-cell proliferations in which nodular fasciitis enters into the differential diagnosis. METHODS AND RESULTS: A database search was performed at the Middlemore Hospital Histopathology Department. All in-house cases diagnosed between 2002 and March 2014 in which nodular fasciitis was considered as a differential diagnosis were retrospectively identified. Twenty cases were retrieved, reviewed and categorized as 'definite', 'possible' or 'definitely not' nodular fasciitis by consensus morphological opinion of three experienced pathologists. FISH analysis for USP6 rearrangement was performed in each case, with a commercially available break-apart probe. Of seven cases that were morphologically categorized as 'definite' nodular fasciitis, six were FISH-positive and one was FISH-negative. Of four cases categorized as 'possible' nodular fasciitis, one was FISH-positive and three were FISH-negative. Nine cases categorized as 'definitely not' nodular fasciitis were all FISH-negative. In the morphologically definitive cases, FISH analysis for USP6 had a sensitivity of 86% and specificity of 100% for a diagnosis of nodular fasciitis. The positive predictive value was 100%, and the negative predictive value 90%. CONCLUSIONS: USP6 FISH is a useful ancillary test in cases where nodular fasciitis is a potential diagnostic consideration.

Potential biomarkers for hepatoblastoma: results from the SIOPEL-3 study.

Hepatoblastoma (HB) is a rare malignant liver tumour found in infants. Many heterogeneous histological tumour subtypes exist. Although survival rates have improved dramatically in recent years with the use of platinum-based chemotherapy, there still exists a subset of HB that does not respond to treatment. There are currently no tumour biomarkers in use and in this study we aim to evaluate potential biomarkers to aid identification of relapse cases that would otherwise be overlooked by current prognostication. This may identify patients that would benefit from more aggressive therapy and could improve overall survival rates. We used immunohistochemistry to analyse the expression of ß-catenin, E-cadherin, Cyclin D1, Ki-67 and alpha-fetoprotein (AFP) protein in tumours from 91 patients prospectively enroled into the SIOPEL 3 clinical trial. The relationship between these biomarkers and clinicopathologic features and patient survival were statistically analysed. We identified one biomarker, Cyclin D1, which has a correlation with mixed epithelial/mesenchymal HB approaching significance (P = 0.07). Survival analysis using these markers has revealed two potential prognostic indicators; Cyclin D1 and Ki-67 (P = 0.01, 0.01).

HGF/c-Met related activation of ß-catenin in hepatoblastoma.

BACKGROUND: Activation of beta-catenin is a hallmark of hepatoblastoma (HB) and appears to play a crucial role in its pathogenesis. While aberrant accumulation of the beta-catenin is a common event in HB, mutations or deletions in CTNNB1 (beta-catenin gene) do not always account for the high frequency of protein expression. In this study we have investigated alternative activation of beta-catenin by HGF/c-Met signaling in a large cohort of 98 HB patients enrolled in the SIOPEL-3 clinical trial. METHODS: We performed immunohistochemistry, using antibodies to total beta-catenin and tyrosine654-phosphorylated beta-catenin, which is a good surrogate marker of HGF/c-Met activation. CTNNB1 mutation analysis was also carried out on all samples. We also investigated beta-catenin pathway activation in two liver cancer cell lines, HuH-6 and HuH-7. RESULTS: Aberrant beta-catenin expression was seen in the cytoplasm and/or nucleus of 87% of tumour samples. Our results also revealed a large subset of HB, 83%, with cytoplasmic expression of tyrosine654-phosphorylated beta-catenin and 30% showing additional nuclear accumulation. Sequence analysis revealed mutations in 15% of our cohort. Statistical analysis showed an association between nuclear expression of c-Met-activated beta-catenin and wild type CTNNB1 (P-value = 0.015). Analysis of total beta-catenin and Y654-beta-catenin in response to HGF activation in the cell lines, mirrors that observed in our HB tumour cohort. RESULTS: We identified a significant subset of hepatoblastoma patients for whom targeting of the c-Met pathway may be a treatment option and also demonstrate distinct mechanisms of beta-catenin activation in HB.

Optimising the management of soft tissue tumours.

The Royal College of Pathologists of Australasia is developing a series of protocols as an educational tool to assist pathologists in the reporting of relevant information for specific cancer specimens. The protocol for the management of soft tissue tumour resections has recently been released, and this document elaborates the relevant literature on which that protocol drew. Sarcoma is uncommon but is associated with significant morbidity and mortality, and its management is complex. Diagnostic errors are not uncommon and these can have disastrous effects on patient outcome. Sophisticated ancillary testing is often an important adjunct to diagnosis and prognostication. Referral to a specialist sarcoma unit is indicated for both adult and paediatric sarcoma.

Nodular regenerative hyperplasia of the liver secondary to azathioprine in a patient with inflammatory bowel disease.

A case of dramatic portal hypertension with massive ascites and splenomegaly is described in a patient with inflammatory bowel disease receiving azathioprine therapy. Liver biopsy confirmed the subtle changes of nodular regenerative hyperplasia and the patient recovered following withdrawal of the azathioprine and commencement of spironolactone. Thrombocytopaenia is an early clue to azathioprine-induced nodular regenerative hyperplasia of the liver.