藤井 裕之

We report a case of a man in his 60s with ROS1 fusion-positive lung adenocarcinoma who developed multiple cystic lesions in both the kidneys and liver during crizotinib treatment. The patient presented with fever, abdominal pain, and oliguria. Contrast-enhanced CT revealed new cystic lesions in both the kidneys and liver, with some showing thick walls, septa, and hyperdense contents. MRI demonstrated heterogeneous signal intensities on T2-weighted images and mixed low to high signal intensities on T1-weighted images. Some cysts displayed T2 hypointense and T1 hyperintense areas along the cyst walls, with diffusion restriction predominantly at the periphery of the masses. Percutaneous drainage of the cysts was performed, and cytology revealed an increase in the number of cells, including neutrophils. However, no malignant cells or microorganisms were detected. Based on these imaging findings and laboratory results, the patient was diagnosed with crizotinib-associated renal and hepatic cysts. Symptoms improved after crizotinib discontinuation, and follow-up imaging showed cyst regression. This is the first report describing MRI findings for crizotinib-associated hepatic cysts. Characteristic MRI findings, such as T2 hypointensity/T1 hyperintensity along the cyst walls and diffusion restriction predominantly at the periphery of the masses, suggesting hemorrhagic components, may help differentiate crizotinib-associated cysts from other lesions, including metastases and abscesses.

Mucosa-associated lymphoid tissue (MALT) lymphoma commonly arises from chronic inflammation or autoimmune diseases, such as Sjögren syndrome (SjS). Although rare, amyloid deposition in MALT lymphoma has been reported. We present a rare case of parotid gland MALT lymphoma in a 49-year-old woman, in whom preoperative diagnosis was challenging due to atypical imaging findings resulting from amyloid deposits. MRI showed T2-hypointense and T1-iso- to slightly hyperintense masses in the left parotid gland and right sublingual gland, with predominant marginal contrast enhancement and no significant diffusion restriction. Additionally, atrophy and fatty replacement of the parenchyma were noted in bilateral parotid glands, suggesting SjS. Left superficial parotidectomy was performed and pathological findings confirmed MALT lymphoma with extensive amyloid deposition. Histopathological findings of the resected parotid gland parenchyma also suggested SjS. MALT lymphoma should be considered in the differential diagnosis of multiple salivary gland masses in patients with suspected SjS. If MRI reveals atypical imaging findings for malignant lymphoma, particularly T2-hypointensity with no significant diffusion restriction, the possibility of amyloid deposition in MALT lymphoma should be considered.

INTRODUCTION: Moderately differentiated neuroendocrine tumors of the larynx are rare malignant tumors that arise from the submucosa of the larynx, for which surgery is the first-line treatment. PRESENTATION OF CASE: We report a case of moderately differentiated neuroendocrine tumor of the larynx, in which the patient, a 74-year-old man, experienced long-term palliation but an unfortunate outcome of death owing to metastasis. Laryngeal endoscopic examination revealed an elevated submucosal lesion on the laryngeal surface of the epiglottis. Computed tomography and magnetic resonance imaging showed a tumor-like lesion demonstrating a contrasting effect in the submucosa of the epiglottis. A biopsy revealed a moderately differentiated neuroendocrine tumor (formerly called an atypical carcinoid), and a horizontal partial laryngectomy was performed. The patient had a good postoperative course; however, three years and ten months after surgery, he experienced recurrence in the upper gastrointestinal tract and carcinoid syndrome and died four years and three months after the surgery. DISCUSSION: The prognosis of laryngeal neuroendocrine tumors remains poor. In this case, local control was possible without irradiation because the resection margins were negative on pathological examination. This case report has been reported in line with the SCARE Criteria. CONCLUSION: Long-term follow-up of this type of tumor is necessary, as distant metastasis is likely to affect prognosis. In addition to surgery, effective adjuvant therapies, including molecular targeted therapies, should be established.

Introduction Low-grade epilepsy-associated tumors are the second most common histopathological diagnoses in cases of drug-resistant focal epilepsy. However, the connection between neuroimaging features and genetic alterations in these tumors is unclear, prompting an investigation into genotype-relevant neuroimaging characteristics. Methods This study retrospectively analyzed neuroimaging and surgical specimens from 46 epilepsy patients with low-grade epilepsy-associated neuroepithelial tumors that had genetic mutations identified through panel sequencing to investigate their relationship to genotypes. Results Three distinct neuroimaging groups were established: Group 1 had indistinct borders and iso T1-weighted and slightly high or high T2-weighted signal intensities without a diffuse mass effect, associated with 93.8% sensitivity and 100% specificity to BRAF V600E mutations; Group 2 exhibited sharp borders and very or slightly low T1-weighted and very high T2-weighted signal intensities with a diffuse mass effect and 100% sensitivity and specificity for FGFR1 mutations; and Group 3 displayed various characteristics. Histopathological diagnoses including diffuse low-grade glioma and ganglioglioma showed no clear association with genotypes. Notably, postoperative seizure-free rates were higher in Group 1 tumors (BRAF V600E) than in Group 2 tumors (FGFR1). Discussion These findings suggest that tumor genotype may be predicted by neuroimaging before surgery, providing insights for personalized treatment approaches.