DICER1 Mutations Enable Rare Tumor Formation

Abstract Introduction/Objective DICER1 is a tumor suppressor gene that imparts a slight increase in tumor formation when mutated. The protein plays a role in processing miRNA that silences transcription. Germline mutations of DICER1 predispose to tumors in a known set of organs and rarely in other locations. However the presence of additional genetic aberrations further increases the likelihood of tumor formation. Acting as a compounding factor, DICER1 mutations can present a constantly shifting cancer phenotype of affected patients. Of particular interest here is the development of both Pineoblastoma and Malignant spindle cell sarcoma in a young patient. Sarcomas are estimated to make up only 10% of pediatric cancers and Pineal masses only 3%. Methods/Case Report This case involves an 8 year old male with a history of Pineoblastoma who originally presented with slowly worsening ataxia. A screening ultrasound on following visits identified an abdominal mass that was confirmed with computed tomography. Subsequent biopsies showed malignant spindle cells arranged in a herringbone pattern. Additionally these cells displayed high mitotic activity and hyperchromatic nuclei. Surprisingly, they also demonstrated extramedullary hematopoiesis. Multiple stains were performed however no significant conclusion could be made. The appearance of this tumor and its rarity prompted a request for a Complete Comprehensive Sarcoma Panel via Next Generation Sequencing. This confirmed the presence of pathologic BRAF and DICER1 genes. From that the diagnosis of DICER1 associated Malignant Spindle Cell Sarcoma was made. BRAF V600E is the most common genetic variant and is seen in multiple cancers but only seen in 1-3% of sarcomas. Pathologic variants of the DICER1 gene exist on exons 13 and 25. The presence of these exon mutations in some way affect DICER1 protein function and compound the effects of the mutated BRAF gene. This situation is unique as such neoplasms are rarely found in the anterior abdominal wall and showcases the effects of DICER1 on rare tumor phenotypes. Results (if a Case Study enter NA) NA Conclusion Continuing research into both DICER1 protein pathways is essential for isolating a diagnosis and guiding treatment. It would seem screening images and genetic testing would benefit pediatric or even adult patients with common and rare cancers. Extra effort made toward this would not be outside the norm as personalized medicine is gradually becoming the standard for cancer treatment.