Prophylactic cranial irradiation (PCI) for limited disease small cell lung cancer is the standard of care for curative treatment of this disease. However, neurocognitive dysfunction is one of the late adverse events of PCI and is often problematic. Recently, hippocampal avoidance prophylactic cranial irradiation (HA-PCI) is sometimes performed to prevent neurocognitive dysfunction after PCI. In HA-PCI, the question is whether or not metastases appear around the hippocampus that were not irradiated. We have experienced a case of perihippocampal meningeal carcinomatosis after HA-PCI. We also draw attention to the potential risks of performing HA-PCI based on this experience.

Introduction: Long-term survivors of whole brain radiation (WBRT) are at significant risk for developing cognitive deficits, but knowledge about the underlying pathophysiological mechanisms is limited. Therefore, we here report a rare case with a singular brain metastasis treated by resection and WBRT that survived for more than 10 years where we investigated the integrity of brain networks using resting-state functional MRI. Methods: A female patient with a left frontal non-small cell lung cancer (NSCLC) brain metastasis had resection and postoperative WBRT (30.0 in 3.0 Gy fractions) and stayed free from brain metastasis recurrence for a follow-up period of 11 years. Structural magnetic resonance imaging (MRI) and amino acid [O-(2-[18F]fluoroethyl)-L-tyrosine] positron emission tomography (FET PET) were repeatedly acquired. At the last follow up, neurocognitive functions and resting-state functional connectivity (RSFC) using resting-state fMRI were assessed. Within-network and inter-network connectivity of seven resting-state networks were computed from a connectivity matrix. All measures were compared to a matched group of 10 female healthy subjects. Results: At the 11-year follow-up, T2/FLAIR MR images of the patient showed extended regions of hyper-intensities covering mainly the white mater of the bilateral dorsal frontal and parietal lobes while sparing most of the temporal lobes. Compared to the healthy subjects, the patient performed significantly worse in all cognitive domains that included executive functions, attention and processing speed, while verbal working memory, verbal episodic memory, and visual working memory were left mostly unaffected. The connectivity matrix showed a heavily disturbed pattern with a widely distributed, scattered loss of RSFC. The within-network RSFC revealed a significant loss of connectivity within all seven networks where the dorsal attention and fronto-parietal control networks were affected most severely. The inter-network RSFC was significantly reduced for the visual, somato-motor, and dorsal and ventral attention networks. Conclusion: As demonstrated here in a patient with a metastatic NSCLC and long-term survival, WBRT may lead to extended white matter damage and cause severe disruption of the RSFC in multiple resting state networks. In consequence, executive functioning which is assumed to depend on the interaction of several networks may be severely impaired following WBRT apart from the well-recognized deficits in memory function.

AIDS-related primary central nervous system lymphoma (AR-PCNSL) is an AIDS-defining disease that usually occurs when the CD4 count is less than 50 cells/μl. The frequency of the disease has substantially decreased in the era of highly active antiretroviral therapy (HAART). Prognosis is poor with rapid progression leading to death within 2-3 months if left untreated.
A 65 years old male presented to medical attention with gait disturbance, weight loss and slight left-sided hemiparesis. Human immunodeficiency virus infection was diagnosed with an initial CD4 count of 116 cells/µl and a viral load of 260,000 copies/ml. Magnetic resonance imaging of the brain revealed three brain lesions involving the right frontal lobe and the left parietal lobe, which on biopsy led to a diagnosis of AR-PCNSL. HAART was initiated with whole-brain radiotherapy (WBRT), and the patient declined systemic chemotherapy. Due to poor performance status, he was transferred to palliative care. Under HAART, he slowly recovered with normalization of CD4 count and undetectable viral load. Medical imaging showed complete remission (CR) of the brain lesions. At 3-year follow-up, the patient remains in CR, but presented mild neurocognitive dysfunction possibly secondary to WBRT.
Nowadays, treatment paradigm parallels that of primary central nervous system lymphoma in the immunocompetent population based on systemic chemotherapy (primarily high-dose intravenous methotrexate and steroids) in association with HAART. The role of WBRT is questionable because of late neurotoxic effects.

Brain metastases from endometrial adenocarcinoma are quite rare. Here, we report a case of a 64-year-old woman who presented with a history of left limb weakness of 45 days\' duration. Her medical history was significant for the endometrial carcinoma diagnosed 13 years earlier, for which she had undergone a total hysterectomy. The patient received a craniotomy and was finally diagnosed with brain metastasis from endometrial adenocarcinoma. We performed a MEDLINE search of the pertinent literature, searching for information focusing on the diagnosis, mechanism, treatment, and prognosis of this rare tumor type.

Primary CNS lymphoma (PCNSL) is a rare diffuse large B-cell lymphoma originating within the central nervous system. The overall incidence of PCNSL is rising, particularly in the elderly population. Immunosuppression is a strong risk factor, but most patients with this tumor are apparently immunocompetent. Diagnosis of PCNSL can be challenging. Non-invasive or minimally invasive tests such as ophthalmological evaluation and spinal fluid analysis may be useful, but the majority of patients require tumor biopsy for definitive diagnosis. Our knowledge concerning optimum treatment of PCNSL is fragmentary due to paucity of adequately sized trials. Most patients are now initially treated with high-dose-methotrexate-based chemotherapy alone, as the addition of whole-brain radiotherapy at standard doses has not been shown to increase survival and does increase the risk of neurological toxicity. Ongoing trials are addressing issues such as the roles of reduced-dose radiotherapy, the addition of the CD20 antibody rituximab to chemotherapy, high-dose chemotherapy followed by autologous stem cell transplantation, and maintenance therapy in the primary management of PCNSL.

Leptomeningeal metastases (LM) are found in approximately 3.8% of non-small cell lung cancer cases with an increased incidence in adenocarcinoma, and approximately one-third of patients will present with concomitant brain metastases. We report the case of a 50-year-old male patient with stage IV exon 19-del-EGFR mutant lung adenocarcinoma who progressed on second-generation TKI therapy with manifestation of symptomatic simultaneous diffuse brain and LM. Whole-brain radiotherapy with concurrent afatinib resulted in an almost complete regression of neurological symptoms as well as good, durable radiological response. Furthermore, treatment was well tolerated with no relevant adverse effects.