[Spontaneous Remission of Encephalitis that Developed 17 Weeks After the Last Dose of Pembrolizumab: A Case Report].

We present a 73-year-old man with a history of lung adenocarcinoma and multiple metastases. He was treated with chemotherapy, including pembrolizumab, but treatment was interrupted due to concurrent drug-induced lung injury. Seventeen weeks after the last dose of pembrolizumab, he developed encephalitis, presenting with a disturbance of consciousness and right hemiplegia. However, his symptoms gradually improved spontaneously and disappeared three weeks after their onset. Late-onset encephalitis after the administration of immune checkpoint inhibitors is rare. In addition, this is the first report of a case in which severe encephalitis recovered spontaneously without leaving sequelae. (Received April 7, 2023; Accepted July 4, 2023; Published October 1, 2023).

Motor end-plate analysis to diagnose immune-mediated myasthenia gravis in seronegative patients.

This study aimed to evaluate the diagnostic usefulness of motor end-plate (MEP) analysis along with clustered acetylcholine receptor (AChR) antibody (Ab) assays in patients with myasthenia-like symptoms but negative routine AChR and muscle-specific kinase (MuSK) Ab tests. MEP analysis of muscle biopsies of the biceps brachii was performed in 20 patients to try to differentiate between those with or without immune-mediated myasthenia gravis (MG). Using a quantitative method, complement C3 deposition and AChR densities in MEPs were examined. Independently, cell-based assays were used to detect serum clustered-AChR Abs. Only five of 20 patients had complement deposition at MEPs; four of these patients had reduced AChR densities similar to those in patients with typical AChR Ab positive MG, and distinct from those in the remaining 15 patients. Two of the four serum samples from these patients had clustered-AChR Abs. All complement-positive patients were considered as having immune-mediated MG and improved with appropriate treatments; although one patient presented with MG 3 years later, the remaining patients had other diagnoses during over 10 years of follow-up. These results suggest the usefulness of MEP analysis of muscle biopsies in diagnosing immune-mediated MG in seronegative patients with myasthenia-like symptoms but, due to the invasiveness of the muscle biopsy procedure, clustered AChR Abs should, if possible, be tested first.

[Neurolymphomatosis Mimicking Inflammatory Neuropathy with Slight FDG Uptake on PET/CT and Distinct MRI Abnormalities in the Brachial Plexus: A Case Report].

A 60-year-old Japanese woman presented with left upper limb numbness and muscle weakness nine months after completing chemotherapy for diffuse large B-cell lymphoma. Magnetic resonance imaging showed distinct signal abnormalities in the left brachial plexus, but positron emission tomography/computed tomography revealed only slight linear 18F-fluorodeoxyglucose uptake along the involved nerves, mimicking inflammatory neuropathy. There have only been a few reports of neurolymphomatosis mimicking inflammatory neuropathy on imaging; therefore, we report the details of our case. (Received March 30, 2020; Accepted May 15, 2020; Published September 1, 2020).

Successful Management of Lupus Nephritis with High Titers of Myeloperoxidase Anti-Neutrophil Cytoplasmic Antibodies Using Tacrolimus.

A 63-year-old Japanese woman with a 30-year history of systemic lupus erythematosus developed macrohematuria and massive proteinuria after seroconversion of myeloperoxidase anti-neutrophil cytoplasmic antibodies (MPO-ANCA). A renal biopsy indicated focal proliferative lupus nephritis (class III A/C) with a fibrous crescent formation. Methylprednisolone pulse therapy (500 mg, 3 successive days) was administered because of progressive proteinuria. Steroid therapy did not suppress the progressive proteinuria; therefore, tacrolimus was added as an alternative immunosuppressive therapy, resulting in the improvement of proteinuria and renal impairment. This case report suggests that MPO-ANCA might play a pathogenic role in the exacerbation of immune-complex-type lupus nephritis.