Histopathologic correlates of opioid-associated injury in CHANTER syndrome: first report of a post-mortem examination.

Opioid-associated brain injury may involve selective regions, including the hippocampi alone, globi pallidi, and cerebellar hemispheres. Opioid-associated amnestic syndrome, for example, is one clinical correlate of hippocampal injury as manifest by MRI abnormality. When all three regions are involved in what may be a more fulminant injury, the syndrome is termed "cerebellar, hippocampal, and basal nuclei transient edema with restricted diffusion (CHANTER)", initially described in 2019. Until now, to our knowledge, there have been no histopathologic correlates to the imaging findings specifically in CHANTER syndrome. Here, for the first time, we present histopathologic findings of the post-mortem brain from a patient who died from complications of CHANTER syndrome following fentanyl intoxication. These observations included microhemorrhage, reactive and necrotic vasculature, eosinophilic neuronal necrosis, axonal swelling and spheroids, and frank infarction. The findings support previous experimental models implicating both hypoxic-ischemic and cytotoxic mechanisms in the tissue damage associated with CHANTER syndrome, though further work is needed to better characterize the exact cellular pathways involved to develop targeted treatments.

Primary Central Nervous System Lymphoma Mimicking Longitudinally Extensive Transverse Myelitis.

Primary central nervous system lymphoma (PCNSL) is an uncommon variant of extra-nodal non-Hodgkin's lymphoma. Three regions can be involved in PCNSL: the brain, the spine, or the vitreus and retina. Spinal PCNSL is rare. It can mimic neoplasm, infection, and inflammation. Diagnostic confirmation is by tissue biopsy, and even then, tissue corroboration may be altered by an inflammatory overlay. We report a 59-year-old woman who we saw after she had 4 weeks of ascending tetraparesis plus bowel and bladder incontinence. Upon presentation, the patient was ventilator-dependent and locked-in. She reported normal sensation through eye-blinking. Magnetic resonance imaging (MRI) brain revealed signal intensity in the bilateral corona radiata and restricted diffusion in the right thalamus, whereas, MRI cervical, and thoracic spine showed T2 prolongation in the anterior medulla and upper cervical cord, with enhancement to C2-C3, and long segment hyperintensity from T1-T9 levels, respectively, suggestive of neuromyelitis optica spectrum disorder. Cerebrospinal fluid cytomorphology and flow cytometry were inconclusive for lymphoma/leukemia, but oligoclonal bands were present. Serum aquaporin-4 (AQP-4) antibodies were negative. MR spectroscopy demonstrated NAA reduction, mild lipid lactate peak, and relative reduction of choline on the side of the lesion, favoring demyelination. She received 5-days of intravenous methylprednisolone, followed by 7 sessions of plasma exchange without clinical improvement. Stereotactic biopsy of the right thalamic lesion revealed diffuse large B-cell lymphoma. PCNSL can mimic a demyelinating process early on, as steroid treatment could disrupt B-cell lymphoma cells, thus masking the correct diagnosis.

Denosumab-Associated Severe Hypocalcemia in a Patient With Chronic Kidney Disease.

Denosumab is a monoclonal antibody directed against the receptor activator of nuclear factor kappa B ligand (RANKL). Denosumab has been shown to reduce the risk of skeletal-related events, including spinal cord compression, pathologic fracture and hypercalcemia of malignancy in patients with bone metastases. Hypocalcemia is a known side effect of denosumab, occurring in an estimated 8-14% of the patients. Here, we present an asymptomatic patient with stage-5 chronic kidney disease and severe hypocalcemia who had received denosumab 1 month earlier.