Evaluation of appropriate conditions for Oncomine DxTT testing of FFPE specimens for driver gene alterations in non-small cell lung cancer.

BACKGROUND: The Oncomine Dx Target Test Multi-CDx System (ODxTT) is a next-generation sequencing panel approved as a companion diagnostic for drugs targeted to corresponding gene alterations in non-small cell lung cancer. However, appropriate slide conditions for ODxTT have remained unclear. METHODS: We focused on the production of the number of tumor cells on a formalin-fixed paraffin-embedded (FFPE) section and the number of prepared slides, designated the TS value, and determined a TS value of ≥4000 as a target slide condition for ODxTT. We evaluated the impact of this condition on ODxTT testing with tumor specimens found to have a TS of <4000 (n = 23) or a TS of ≥4000 (n = 142). RESULTS: A positive correlation was apparent between the TS value and the concentrations of both DNA and RNA. Among the 142 samples with a TS of ≥4000, a sufficient concentration of DNA or RNA for ODxTT analysis was achieved in 100% and 98% samples, respectively. Among samples explored for driver gene alterations after determination of the target slide condition (TS ≥4000), most (84.9%) had a TS of ≥4000 and were submitted for ODxTT analysis. CONCLUSION: Our findings indicate that a TS of ≥4000 is a feasible and relevant criterion for ODxTT testing, and its adoption should help to improve the success rate of such testing in clinical practice.

Radiation-induced spinal cord glioblastoma with cerebrospinal fluid dissemination subsequent to treatment of lymphoblastic lymphoma.

BACKGROUND: Radiation-induced glioma arising in the spinal cord is extremely rare. We report a case of radiation-induced spinal cord glioblastoma with cerebrospinal fluid (CSF) dissemination 10 years after radiotherapy for T-cell lymphoblastic lymphoma. CASE DESCRIPTION: A 32-year-old male with a history of T-cell lymphoblastic lymphoma presented with progressive gait disturbance and sensory disturbance below the T4 dermatome 10 years after mediastinal irradiation. Gadolinium-enhanced magnetic resonance (MR) imaging revealed an intramedullary tumor extending from the C6 to the T6 level, corresponding to the previous radiation site, and periventricular enhanced lesions. In this case, the spinal lesion was not directly diagnosed because the patient refused any kind of spinal surgery to avoid worsening of neurological deficits. However, based on a biopsy of an intracranial disseminated lesion and repeated immmunocytochemical examination of CSF cytology, we diagnosed the spinal tumor as a radiation-induced glioblastoma. The patient was treated with radiotherapy plus concomitant and adjuvant temozolomide. Then, the spinal tumor was markedly reduced in size, and the dissemination disappeared. CONCLUSION: We describe our detailed diagnostic process and emphasize the diagnostic importance of immunocytochemical analysis of CSF cytology.