Primary Diffuse Leptomeningeal Melanomatosis in a Child with Extracranial Metastasis: Case Report

Primary meningeal melanomatosis is an extremely rare tumor with very few documented responses to treatment. A 3-year-old male with a complex past medical history, including prematurity and shunted hydrocephalus, was diagnosed with primary meningeal melanomatosis with peritoneal implants. Molecular testing revealed an NRAS Q61R mutation. The patient received proton craniospinal radiation followed by immunotherapy with nivolumab (1 mg/kg) and ipilimumab (3 mg/kg) IV every 3 weeks and, upon progression, he was switched to a higher dose of nivolumab (3 mg/kg IV every 2 weeks) and binimetinib (24 mg/m2/dose, twice a day). The patient had significant improvement of CNS disease with radiation therapy and initial immunotherapy but progression of extracranial metastatic peritoneal and abdominal disease. Radiation was not administered to the whole abdomen. After two cycles of nivolumab and treatment with the MEK inhibitor binimetinib, he had radiographic and clinical improvement in abdominal metastasis and ascitis. He ultimately died from RSV infection, Klebsiella sepsis, and subdural hemorrhage without evidence of tumor progression. This is the first report of a child with primary meningeal melanomatosis with extracranial metastatic disease with response to a combination of radiation, immunotherapy and MEK inhibitor therapy.

RARE-30. Novel collision tumor of craniopharyngioma and ependymoma in a pediatric patient: a case study

Collision tumors are rare tumors comprised of two distinct histologies. In this case report, we discuss a suprasellar collision tumor consisting of adamantinomatous craniopharyngioma and supratentorial ependymoma in a pediatric patient. Case Presentation: Our patient was a two-year-old female with progressive craniopharyngioma status post cyst decompression with Ommaya reservoir placement, subcutaneous peginterferon, Ommaya taps, and subtotal resection. An MRI three months post-resection showed progression and treatment was started with subcutaneous interferon alfa. After eight weeks, she presented with new onset headaches and vomiting. MRI demonstrated tumor progression with associated obstructive hydrocephalus. She underwent a subtotal resection. Pathology revealed recurrent adamantinomatous craniopharyngioma and a 0.5cm ependymoma with classic histomorphology lacking anaplasia features. The ependymoma was positive for GFAP immunostain and EMA immunohistochemistry highlighted a ‘dot-like’ reaction. The Ki-67 proliferation index was very low (<1%). The limited diagnostic material precluded further genomic characterization of the ependymoma. The previous pathology was reviewed and no ependymoma was identified. Spine MRI was negative for metastatic disease. CSF cytology was negative for malignant cells. Following recovery from surgery, she received 54Gy (RBE) focal proton radiation. Eight months from completion of therapy, surveillance MRI shows stable residual tumor. Genetic work-up for cancer predisposition syndrome is in process despite no strong family history of cancer. Discussion: Due to the patient’s young age at diagnosis, our initial treatment strategy was to delay radiotherapy and utilize other treatment options. Following diagnosis with a collision tumor, the patient proceeded to radiotherapy to manage both tumor components. The role of interferon in the development of a collision tumor in this patient in unknown, but we suspect it to be unrelated. Conclusion: To our knowledge, this is the first documented case of a suprasellar collision tumor comprised of craniopharyngioma and ependymoma. Discovery of the collision tumor impacted the patient’s treatment plan.

Prolongation of radiotherapy duration is associated with inferior overall survival in patients with pediatric medulloblastoma and central nervous system primitive neuroectodermal tumors

BACKGROUND

The importance of radiotherapy (RT) duration in medulloblastoma in the modern era of chemotherapy has not been well elucidated. The aim of this study was to determine the impact of RT treatment duration on overall survival (OS) in pediatric medulloblastoma and cenral nervous system neuroectodermal tumors (PNETs).

METHODS

The National Cancer Database (NCDB) was queried to identify patients with newly diagnosed medulloblastoma and CNS PNETs diagnosed between 2004 and 2014. Patients were excluded if they had extraneural metastasis, did not receive standard craniospinal irradiation dose, had a nonstandard total dose outside of 54 or 55.8 Gy, did not receive adjuvant chemotherapy, or if the RT duration was outside of the expected range of 37 to 80 days. The Kaplan-Meier estimator was used to estimate the association between RT duration (≤45 days or >45 days) and OS. Multivariate Cox regression was used to assess other confounders of OS.

RESULTS

Six-hundred twenty-five patients met inclusion criteria, of which 181 were assigned to the "RT long" (>45 days) cohort (29.0%) and 444 (71.0%) to the "RT short" group (≤45 days). The five-year OS for the "RT short" compared with "RT long" cohort was 82.2% versus 70.9%, respectively (log-rank, P < 0.0037). For average risk patients, the five-year OS was 84.6% versus 86.4% for "RT short" and "RT long," respectively (log-rank, P = 0.40). However, for high-risk patients, five-year OS was 77.7% versus 51.0% (log-rank, P < 0.0001) in the "RT short" and "RT long" cohorts.

CONCLUSION

For patients with high-risk medulloblastoma and CNS PNETs, RT duration >45 days was associated with inferior OS.