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Ectomesenchymal chondromyxoid tumor is a rare and benign neoplasm with a predilection for the anterior dorsal tongue. Despite morphologic heterogeneity, most cases are characterized by a proliferation of bland spindle cells with a distinctive reticular growth pattern and myxoid stroma. The immunophenotype of these neoplasms is likewise variable; most cases express glial fibrillary acid protein and S100 protein, with inconsistent reports of keratin and myoid marker expression. The molecular pathogenesis is poorly understood; however, a subset of cases has been reported to harbor EWSR1 gene rearrangement. Following identification of an RREB1-MKL2 fusion gene by RNA Sequencing in an index patient, a retrospective review of additional cases of ectomesenchymal chondromyxoid tumors was performed to better characterize the clinical, immunohistochemical, and molecular attributes of this neoplasm. A total of 21 cases were included in this series. A marked predisposition for the dorsal tongue was confirmed. Most cases conformed to prior morphologic descriptions; however, hypercellularity, hyalinized stroma, and necrosis were rare attributes not previously emphasized. The neoplastic cells frequently coexpressed glial fibrillary acid protein, S100 protein, keratin, smooth muscle actin, and/or desmin; a single case was found to contain significant myogenin expression. An RREB1-MKL2 fusion product was identified in 19 tumors (90%), a single tumor (5%) had an EWSR1-CREM fusion product, and the remaining case lacked any known fusion gene by RNA Sequencing. The latter 2 cases subtly differed morphologically from many in the cohort. This series illustrates that recurrent RREB1-MKL2 fusions occur in most, perhaps all, cases of ectomesenchymal chondromyxoid tumor.

Introduction: Patients are receiving increasing access to their electronic medical record (EMR) and laboratory results, including pathology reports, are amongst the most frequently accessed pieces of information. MyPathologyReport.ca is a novel website exclusively providing pathology education to patients, designed to help patients understand the language of pathology and to effectively navigate their pathology report. Feedback on this free online tool was solicited from healthcare providers to determine whether MyPathologyReport.ca would serve the needs of their patient population. Methods: An online questionnaire was distributed to targeted healthcare providers at the Ottawa Hospital, the Children's Hospital of Eastern Ontario, and select community practices. Respondents were required to navigate MyPathologyReport.ca and complete a 15- question survey regarding their use of pathology reports and whether MyPathologyReport.ca provided useful information for their patients. Results: There were 22 respondents across six specialties, including multiple surgical subspecialties, pediatrics, medical genetics, and family medicine. Over 80% reported that all features of MyPathologyReport.ca were either very useful or extremely useful, including: i) how to read a pathology report; ii) an illustrated pathology dictionary; and iii) articles outlining the most common pathological diagnoses. 72% of respondents stated they were somewhat likely or very likely to recommend MyPathologyReport.ca to a patient. Conclusion: An informed patient is an active member of the healthcare team. Our feedback questionnaire demonstrates that clinicians find MyPathologyReport.ca to be a useful patient resource. Next steps involve longitudinal assessment of MyPathologyReport.ca from non-medical community members and evaluation of patient satisfaction and knowledge with access to this resource. [ABSTRACT FROM AUTHOR]

Objective: Pleomorphic lipoma/spindle cell lipoma (PL/SCL) is a benign lipomatous tumour that may mimic well-differentiated liposarcoma (WDLPS). Using fluorescence in situ hybridization (FISH) for MDM2 amplification as the gold standard for diagnosis of WDLPS, we studied the utility of CD34, S100, and the relatively new marker HMGA2 in the evaluation of lipomatous tumours with atypia. In addition, we describe 3 cases of PL that occurred in unusual locations including the arm, forehead and retroperitoneum (previously reported only once in an English-language journal without MDM2 analysis). Method: Using MDM2 FISH and immunohistochemistry (IHC) for CD34, S100 and HMGA2, we analyzed 16 cases of PL/SCL and 11 cases of WDLPS. Data and Results: PL/SCL was uniformly CD34 positive and negative for S100 and HMGA2, while WDLPS was HMGA2 positive (100%) and negative for S100 (91%) and CD34 (55%). In all tested cases, MDM2 was amplified in WDLPS (7/7) and not amplified in PL/SCL (5/5). The retroperitoneal PL shared the same morphology, IHC and MDM2 status as the other PL. Conclusions: 5 cases of WDLPS showed aberrant staining with CD34, which was often difficult to interpret because of background staining. Due to its tidy nuclear staining and ease of interpretation, as well as its superior performance at differentiating PL/SCL and WDLPS, utilizing HMGA2 with CD34 is especially useful. In addition, the morphology and IHC should be used in concert with MDM2 analysis in the diagnosis of difficult lipomatous tumours. Finally, though rare, retroperitoneal PL/SCL do exist and must be considered in this location. [ABSTRACT FROM AUTHOR]