An Adult Patient With Rare Primary Intracranial Alveolar Rhabdomyosarcoma.

We report a rare case of primary intracranial alveolar rhabdomyosarcoma (ARMS) in the right temporal lobe of a 51-year-old male. ARMS is one of 3 histological subtypes of rhabdomyosarcoma that most commonly presents in older children and younger adults. To our knowledge, there have been no prior published reports of primary intracranial ARMS in adults. Known cases of intracranial ARMS in adults are due to central nervous system (CNS) metastases from the head and neck and extremities. Diagnostic workup did not reveal any primary source outside the CNS. Given that risk factors for ARMS have not been studied in adults, it is difficult to ascertain what aspects of this patient's clinical history may have contributed to his diagnosis. Interestingly, he had prior history of traumatic brain injury requiring evacuation of a right fronto-temporal intraparenchymal hematoma.

Spinal Pleomorphic Xanthoastrocytoma With a QKI-RAF1 Fusion.

Pleomorphic xanthoastrocytoma (PXA) is a slow-growing neoplasm that predominantly affects the pediatric and young adult population. This neoplasm has a good prognosis, with a median 10-year survival rate of 70%. The majority of tumors are supratentorial and arise in the temporal lobe, while spinal tumors are extremely rare, with only 8 reported cases. Molecular perturbations involving the MAPK/ERK signaling pathway have been described in PXAs. The most common mutation is BRAF V600E in 60%-80% of cases. Other mechanisms activating this pathway in the absence of this mutation are rare and include CRAF (RAF1) fusion genes. We report a PXA case in the cervical spinal cord of a 49-year-old man with slowly progressive coordination difficulties and extremity numbness. The tumor was negative for the V600E mutation, but 2 RNA sequencing platforms detected a QKI-RAF1 fusion (t(6; 3)(q26; p25)), which has not been previously reported in PXAs. This fusion is known to activate MAPK/ERK and PI3K/mTOR signaling. Although first- and second-generation RAF inhibitors are predicted to be ineffective, this fusion may be targetable by the novel RAF inhibitor LY3009120 and to some extent by the MEK inhibitor trametinib. Genetic analysis to screen for MAPK/ERK pathway mutations is warranted on PXAs negative for the V600E mutation.

Recurrent encephaloclastic cyst induced by intraventricular topotecan.

OBJECTIVE: To report two rare cases of encephaloclastic cyst induced by intraventricular topotecan. To share our experience in diagnosing and treating this rare disease. BACKGROUND: Ommaya reservoirs provide fast access and reliable drug delivery to cerebral spinal fluid. They are routinely utilized for the administration of intrathecal chemotherapy accounting for greater than 80% of cases for which they are used. Complications of Ommaya reservoir placement and its use consist of infectious and other late noninfectious causes. Encephaloclastic cysts provoked by intraventricular chemotherapy are very uncommon. The pathogenesis may result from alterations in CSF pulsations with retrograde flow of intraventricular chemotherapy into the brain parenchyma and subsequent development of a local chemical encephalopathy. It has been previously reported with methotrexate use but never with topotecan administration. METHODS: We report two rare cases of encephaloclastic cyst with intraventricular topotecan use. The patients were diagnosed and treated at The University of Texas MD Anderson Cancer Center. They consented to the publication of their laboratory results and imaging studies for educational purposes. RESULT: The patients presented with metastatic cancers (breast/lung) complicated by leptomeningeal disease. Ommaya reservoirs were placed in both cases and patients were initiated on intraventricular topotecan at 0.4 mg twice weekly. After approximately 12 intraventricular treatments, both patients developed confusion, seizures and headaches. MRI of the brain demonstrated cystic dilatation of the brain parenchyma around the catheter that connects to the reservoir dome and delivers the drug to the intraventricular space. The catheter was surrounded by vasogenic edema. Catheters were removed and analyzed and were found to be intact. CSF analyses showed no evidence of infection or malignancy. Intraventricular topotecan was discontinued and both patients demonstrated sustained clinical and radiological responses. CONCLUSION: These cases highlight an atypical complication of intraventricular use of topotecan with successful management.