Identification of novel GNAS mutations in intramuscular myxoma using next-generation sequencing with single-molecule tagged molecular inversion probes

Contains fulltext : 201341.pdf (publisher's version ) (Open Access

Rapid microwave-stimulated fixation of entire prostatectomy specimens

Conventional fixation of large solid surgical specimens is a slow process. Consequently, autolytic damage to tissues may occur if the fixative does not reach the central part of the specimen in time. However, as there is also a time relationship between formalin fixation and antigen masking, fixation for too long can also be detrimental. In seeking the optimum balance for fixation, microwave irradiation might be of assistance. This study set out to evaluate methods for fixing entire prostate glands within a brief period of time, using microwave-stimulated formalin fixation. The results show that entire prostates can be optimally fixed if formalin is present throughout the tissue as the temperature is increased by microwave irradiation. This is achieved by injecting the fixative into the prostate at multiple sites immediately following prostatectomy. The technique described ensures standardization of a critical step during tissue processing, leading to uniform microscopic results with both routine and immunohistochemical stains. It is a simple, rapid method, suitable for routine diagnostic use. Using this modified approach, DNA of much larger sizes can be extracted from paraffin-embedded material, which could expand the possibilities for molecular analysis

Solitary fibrous tumor – clinicopathologic, immunohistochemical and molecular analysis of 28 cases

BACKGROUND: Solitary fibrous tumor is a mesenchymal tumor of fibroblastic type, which can affect any region of the body. Recently, a recurrent gene fusion NAB2-STAT6 has been identified as molecular hallmark. The NAB2-STAT6 fusion leads to EGR1 activation and transcriptional deregulation of EGR1-dependent target genes and is a driving event in initiation of SFT. In this study, we report the clinicopathologic and RT-PCR findings and evaluated expression of STAT6 and EGR1 protein in a cohort of 28 SFTs. METHODS: 28 patients with a median age of 54 years were included with SFTs originating at different sites, most occurring in the lung and pleura (9, 32%), 5 in soft tissues of the lower extremities (18%) and 5 in the head and neck (18%). For detection of the NAB2-STAT6 fusion gene, RT-PCR was performed using RNA extracted from formalin-fixed and paraffin-embedded tissues. Immunohistochemistry was performed on all cases with antibodies against STAT6 and EGR1. RESULTS: All patients were treated by surgery, 3 with adjuvant chemo- or radiotherapy. Follow-up data of 18 patients could be obtained of which 2 patients died of metastatic disease 13 months and 52 years after first diagnosis. Sixteen patients have no evidence of disease with a median follow up of 29.5 months (range 7 – 120 months). NAB2-STAT6 fusion transcripts were found in 19/28 cases (68%). The most common fusion was between NAB2 exon 4 and STAT6 exon 3 (11/19, 58%), mainly occurring in pleuropulmonary lesions. All cases showed strong nuclear expression of STAT6 (28/28, 100%) while EGR1 showed low-level variable nuclear expression in all samples, comparable with the EGR1 expression results of the control group. CONCLUSIONS: The identification of the NAB2-STAT6 fusion in SFTs can provide important diagnostic information, especially in cases with aberrant morphology or when biopsy material is limited. STAT6 immunohistochemistry is another useful tool in diagnosing SFT. EGR1 immunohistochemistry indicates low-level protein expression in accordance with EGR1 activation due to distorted NAB2 activity. VIRTUAL SLIDES: The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/13000_2014_22