Mixed neuronal-glial tumors are rare and challenging to subclassify. One recently recognized variant, papillary glioneuronal tumor (PGNT), is characterized by prominent pseudopapillary structures and glioneuronal elements. We identified a novel translocation, t(9;17)(q31;q24), as the sole karyotypic anomaly in two PGNTs. A fluorescence in situ hybridization (FISH)-based positional cloning strategy revealed SLC44A1, a member of the choline transporter-like protein family, and PRKCA, a protein kinase C family member of serine/threonine-specific protein kinases, as the 9q31 and 17q24 breakpoint candidate genes, respectively. Reverse transcription-polymerase chain reaction (RT-PCR) analysis using a forward primer from SLC44A1 exon 5 and a reverse primer from PRKCA exon 10 confirmed the presence of a SLC44A1-PRKCA fusion product in both tumors. Sequencing of each chimeric transcript uncovered an identical fusion cDNA junction occurring between SLC44A1 exon 15 and PRKCA exon 9. A dual-color breakpoint-spanning probe set custom-designed for interphase cell recognition of the translocation event identified the fusion in a third PGNT. These results suggest that the t(9;17)(q31;q24) with the resultant novel fusion oncogene SLC44A1-PRKCA is the defining molecular feature of PGNT that may be responsible for its pathogenesis. The FISH and RT-PCR assays developed in this study can serve as valuable diagnostic adjuncts for this rare disease entity.
Objective: Retrospectively assess the efficacy of lumbar cerebrospinal fluid (CSF) drainage placed preoperatively in skull base operations in decreasing the incidence of postoperative CSF fistula. Methods: A retrospective review of 150 patients undergoing a posterior fossa craniotomy from 1989 to 2000 was conducted. Patients were divided into those receiving preoperative lumbar drains and those that did not. The rates of postoperative CSF leakage were compared between the two groups. Patient data were analyzed to determine if there were other comorbidities affecting the postoperative incidence of CSF leakage such as smoking, diabetes, or hypertension. Results: Between 1989 and 1994, 25/72 (35%) patients with no preoperative lumbar drain had a postoperative CSF leak. From 1995 to 2000, 9/78 (12%) patients with a preoperative lumbar drain had a CSF leak. This was a 23% decreased incidence of postoperative CSF leakage and a significant decrease in the probability (p < 0.001) of CSF leakage in patients treated with a preoperative lumbar drain. The comorbidities of diabetes, smoking, or hypertension did not increase the probability of a CSF leak (p ¼ 0.43). Conclusions: A preoperatively placed lumbar drain can significantly lower the rate of postoperative CSF leakage after skull base surgery. The drain is a welltolerated adjunct to dural closure and helps increase surgical exposure of the posterior fossa. The comorbidities of diabetes, smoking, or hypertension do not contribute to an increased rate of CSF leakage.
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