Prevalence and diagnostic significance of non-invasive follicular thyroid neoplasm with papillary-like nuclear features in Japan-A multi-institutional study.

This multi-institutional study investigated non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) frequency and its diagnostic significance in Japan. We reviewed 4008 thyroid nodules resected in six institutions before NIFTP was proposed. Overall, 26 cases diagnosed as non-invasive encapsulated follicular variant of papillary thyroid carcinoma (PTC) and 145 cases of follicular thyroid adenoma (FTA) were included. Of these nodules, 80.8% and 31.0%, respectively, were NIFTPs. In five institutions, NIFTPs were more commonly found in FTA than in PTC nodules. When NIFTP was included with PTC, the overall prevalence was 2.3%, with rates in five institutions below 5.0% (0.8%-4.4%). One NIFTP case with nuclear score 3 revealed nodal metastasis 2.5 years post-resection, and the carcinoma cells were immunohistochemically positive for BRAF. FTAs or NIFTPs with nuclear score 2 did not metastasize. NIFTP was more common among FTA than among PTC nodules, possibly due to underdiagnosis of PTC on nuclear findings. Considering the clinical findings, molecular pathogenesis, and therapeutic strategy in Japan, NIFTP with nuclear score 2 is not different from FTA, and use of this entity terminology is not meaningful. In contrast, NIFTP with nuclear score 3 has potential for metastasis and BRAFV600E mutation. Therefore, in NIFTP cases, nuclear scores 2 and 3 should be separately reported.

[Urothelial Carcinoma within a Calyceal Diverticulum Difficult to Distinguish from Cystic Renal Cell Carcinoma].

A 64-year-old man visited our hospital because of right renal cyst and microscopic hematuria which was found in a medical checkup. Contrast computed tomography (CT) and contrast magnetic resonance imaging (MRI) suggested cystic renal cell carcinoma. A laparoscopic nephrectomy was performed, and the surgical specimens showed urothelial carcinoma within the calyceal diverticulum. At a later date, ureterectomy was performed. The surgical specimens had no malignant findings. There has been no recurrence. To our knowledge only 10 cases of urothelial carcinoma within the calyceal diverticulum have beenreported inJapan. A few cases have beenreported overseas.

[A Case Report : Primary Urothelial Carcinoma of the Prostate Producing Interleukin-6 Detected from a Fever].

A 72-year-old man visited a hospital because of a fever and fatigue. His fever persisted and computed tomography revealed a tumor of the prostate. The patient was referred to our hospital with a suspicion of prostate cancer. The blood test showed increased serum C-reactive protein (CRP) level without any infectious findings. Tumor markers including prostate specific antigen were within the normal range and urine cytology was negative. Prostate needle biopsy revealed urothelial carcinoma. No tumor was detected in other areas of the urinary tract. Therefore we diagnosed the patient with primary urothelial carcinoma of the prostate, cT3N0M0. Serum interleukin-6 (IL-6) elevated up to 68 ng/ml. We were not able to detect any metastatic lesions and performed radical cystoprostatectomy and ileal conduit. Serum CRP and IL-6 levels decreased and the fever declined. There has been no relapse 52 months after the surgery.

Aggressive cribriform-morular variant of papillary thyroid carcinoma: Report of an unusual case with pulmonary metastasis displaying poorly differentiated features.

The cribriform-morular variant of papillary thyroid carcinoma (CMV-PTC) is a rare morphologic entity in which metastasis rarely occurs. Until now, only three cases of metastasis by CMV-PTC have been reported. We present a rare sporadic case of CMV-PTC with multiple lung metastases in a 28-year-old female, 3 years after total thyroidectomy. The lung tumor was not encapsulated but well-circumscribed and showed a mixture of cribriform, papillary, and solid patterns of growth with necrosis. The tall columnar carcinoma cells did not display the typical nuclear features of PTC. Carcinoma cells were positive for thyroid transcription factor 1, paired-box gene 8, estrogen receptor, progesterone receptor, and adenomatous polyposis coli, and showed positive nuclear and cytoplasmic staining for ß-catenin. Carcinoma cells were negative for thyroglobulin and CDX-2, and the Ki-67 labeling index was 22.1%. This immunoprofile suggests a pathological diagnosis of metastasis by a CMV-PTC displaying poorly differentiated features. To the best of our knowledge, our case is the first report of CMV-PTC with pulmonary metastasis that was confirmed by histological and immunohistochemical examinations. The present case suggests that CMV-PTC with a high Ki-67 labeling index may cause visceral metastasis.

A rare case of ectopic papillary thyroid carcinoma transformed into squamous cell carcinoma.

A rare case of a metastatic ectopic papillary thyroid carcinoma (PTC) of the lung that transformed into a squamous cell carcinoma (SCC) that resembles pulmonary SCC is reported. A subcutaneous ectopic PTC in the left anterior neck area, together with a normal thyroid gland, were excised. The ectopic PTC showed thyroglobulin, TTF-1 and PAX-8 immunoreactivity and a BRAF V600E mutation. During the post-operative follow-up period, a rapidly growing 2 cm nodular lesion in the lower left lobe of the lung was detected. The lung tumor consisted of solid sheets and nests of squamous cells but without the nuclear features of PTC. Neither papillary nor follicular structures of cancer cells were identified. Carcinoma cells were positive for TTF-1, PAX-8, p40, CK14, and p63, while showing a high Ki-67 labeling index and a BRAF V600E mutation. These results support our interpretation of a PTC that originated from ectopic thyroid tissue in the left anterior neck and that developed a lung metastasis showing squamous cell differentiation.

[A Case of Clear Cell Adenocarcinoma Arising from a Female Urethral Diverticulum].

Adenocarcinoma arising from the female urethral diverticulum is very rare, as only about 100 cases have been reported worldwide. An 82-year-old woman presented with asymptomatic macrohematuria. A transvaginal examination revealed a firm circular mass on the anterior vaginal wall. Cystourethroscopy showed a urethral tumor, which was determined to be clear cell adenocarcinoma after transurethral resection of the urethral tumor. However, we could not resect all of the tumor, so anterior pelvic exenteration and ileal conduit urinary diversion were performed. The final pathological diagnosis was clear cell adenocarcinoma arising from the urethral diverticulum. However multiple lymph node metastases appeared 10 months after surgery. The patient refused additional therapy and died 23 months after surgery.

A rare case of poorly differentiated thyroid carcinoma probably arising from a nodular goiter.

BACKGROUND: Some poorly differentiated thyroid carcinomas (PDTC) arise from pre-existing, well-differentiated carcinomas of follicular cell origin; however, others most likely arise de novo. The case of a PDTC adjacent to a pre-existing nodular goiter is very rare. CASE PRESENTATION: A patient had a PDTC, a widely invasive, cellular tumor with cells that lacked the nuclear features of a papillary thyroid carcinoma. Carcinoma cells were arranged in trabecular, solid, and microfollicular histological patterns and displayed high mitotic activity. A nodule partially encapsulated in a thick fibrous capsule was found adjacent to the PDTC. The nodule was composed of small or dilated follicles, without papillary carcinoma-like nuclear features, that were consistent with a nodular goiter. The PDTC showed a high Ki-67 labeling index and an NRAS gene mutation (codon 61, Q61K). CONCLUSION: These results support our diagnosis of a PDTC, probably arising from a nodular goiter.

[Solitary Fibrous Tumor in the Retroperitoneum : A Case Report].

A 55-year-old man was diagnosed with an abdominal tumor and referred to our department. Abdominal contrast-enhanced computed tomography revealed a 15-cm tumor in the retroperitoneum. The inferior vena cava was compressed ventrally, the right ureter laterally, and the right kidney toward the head. Part of the tumor was situated on the dorsal side of the abdominal aorta. A preoperative diagnosis of neurogenic tumor or a type of sarcoma was made. We performed en bloc resection of the tumor. The right kidney was also resected. We exfoliated between the tumor and inferior vena cava without temporary interruption. The final diagnosis was a solitary fibrous tumor. The patient received no adjuvant therapy. Neither recurrence nor metastasis has been detected for 8 months postoperatively.

Clinical impact of high-quality testing for peritoneal lavage cytology in pancreatic cancer.

In pancreatic ductal adenocarcinoma (PDAC) patients, the importance of peritoneal lavage cytology, which indicates unresectability, remains controversial. This study sought to determine whether positive peritoneal lavage cytology (CY+) precludes pancreatectomy. Furthermore, we propose a novel liquid biopsy using peritoneal lavage fluid to detect viable peritoneal tumor cells (v-PTCs) with TelomeScan F35, a telomerase-specific replication-selective adenovirus engineered to express green fluorescent protein. Resectable cytologically or histologically proven PDAC patients (n = 53) were enrolled. CY was conducted immediately following laparotomy. The resulting fluid was examined by conventional cytology (conv-CY; Papanicolaou staining and MOC-31 immunostaining) and by the novel technique (Telo-CY; using TelomeScan F35). Of them, 5 and 12 were conv-CY+ and Telo-CY+, respectively. All underwent pancreatectomy. The two double-CY+ (conv-CY+ and Telo-CY+) patients showed early peritoneal recurrence (P-rec) postoperatively, despite adjuvant chemotherapy. None of the three conv-CY+ Telo-CY- patients exhibited P-rec. Six of the 10 Telo-CY+ conv-CY- patients (60%) relapsed with P-rec. Of the remaining 38 double-CY- [conv-CY-, Telo-CY-, conv-CY± (Class III)] patients, 3 (8.3%) exhibited P-rec. Although conv-CY+ status predicted poor prognosis and a higher risk of P-rec, Telo-CY was more sensitive for detecting v-PTC. Staging laparoscopy and performing conv-CY and Telo-CY are needed to confirm the indication for pancreatectomy.

Monoclonality of composite large-cell neuroendocrine carcinoma and invasive intestinal-type mucinous adenocarcinoma of the cervix: a case study.

A rare case of mixed carcinoma of the cervix is reported, composed of a large-cell neuroendocrine carcinoma and an invasive intestinal-type mucinous adenocarcinoma. The large-cell neuroendocrine carcinoma was composed of solid nests, sheets, and trabeculae of medium-sized to large-sized cells, and was positive for chromogranin-A and CD56. The invasive intestinal-type mucinous adenocarcinoma showed sparsely scattered immunoreactivity for chromogranin-A. Using an X-chromosome clonality assay, these 2 components showed patterns of monoclonality. These results suggest that the large-cell neuroendocrine carcinoma may have arisen from the invasive mucinous adenocarcinoma.

Lenvatinib-refractory thymic mucinous carcinoma with PIK3CA mutation.

Mucinous adenocarcinoma, a very rare type of thymic carcinoma, is aggressive and has a poor prognosis. The optimal treatment for advanced thymic mucinous adenocarcinoma has not yet been established because of its rarity. An oral multi-tyrosine kinase inhibitor, lenvatinib, was approved for treatment of thymic carcinoma in March 2021 in Japan. However, to the best of our knowledge, there are no published reports concerning lenvatinib for thymic mucinous adenocarcinoma. Herein, we report a 39-year-old woman who presented with a 70 mm multilocular cystic tumor in her left anterior mediastinum and a massive pericardial effusion. We diagnosed a Masaoka stage IVb thymic mucinous adenocarcinoma with multiple metastases to the liver and bones, and pericardial dissemination on the basis of the pathologic findings on examination of a video-assisted thoracoscopic tumor biopsy and radiological examinations. She received paclitaxel-carboplatin-based chemotherapy, but developed a left cerebellar metastasis. Second-line chemotherapy with lenvatinib failed to suppress the tumor. She died of cancer progression 5 months after presentation. Here, we report what we believe to be the first case of a thymic mucinous adenocarcinoma treated with lenvatinib. Our patient's thymic mucinous adenocarcinoma was refractory to both cytotoxic chemotherapy and lenvatinib. Using next-generation sequencing, we identified phosphatidylinositol 3-kinase catalytic subunit alpha mutation in the tumor. We suspected an association between this mutation and resistance to lenvatinib. We therefore recommend performing next-generation sequencing when considering introduction of lenvatinib for thymic mucinous adenocarcinoma. A surgical procedure may be necessary for accurate diagnosis and genetic analysis of this histological tumor type.

Sarcoid-Like Granulomatosis of the Lung Related to Durvalumab After Chemoradiation for Pulmonary Squamous Cell Carcinoma.

Sarcoid-like granulomatosis is a unique immune-related adverse event (irAE) in cancer patients treated with immune checkpoint inhibitors (ICIs). This irAE is infrequent, reported to range from 2% to 22.2% of melanoma treated with ICI. In a case of granulomatosis localized in the lung, it is difficult to differentiate granulomatosis from cancer progression or metastases. Herein, we report a case of ICI-induced sarcoid-like granulomatosis of the lung, which was confusable with localized recurrence of the primary lung cancer. A 56-year-old woman with c-stage IIIA of pulmonary squamous cell carcinoma in the right lower lobe received chemo-radiotherapy with two courses of cisplatin and vinorelbine and concurrent thoracic irradiation, followed by 1-year durvalumab consolidation therapy. The tumor in the right S6 grew and presented abnormal uptake by fluorodeoxyglucose positron emission tomography (FDG-PET), 1.5 years after durvalumab. Neither computed tomography (CT) nor FDG-PET found mediastinal and distant metastases. She underwent right lower lobe lobectomy. Histopathologically, the tumor and sampled lymph nodes contained no residue of carcinoma cells but presented diffuse epithelioid granuloma with infiltration of inflammatory cells, partial necrotic lesions and many multinucleated giant cells. In immunohistochemical stains, CD3+ and CD8+ T cells predominantly infiltrated, while there were few CD4+ T cells and a small number of CD20+ B cells. We followed her without steroid and other immunosuppressant drug. We should pay attention to the development of sarcoid-like granulomatosis as a rare irAE, which is difficult to be differentiated from cancer progression.

A Case of Radiation-Associated Vertebral Compression Fracture Mimicking Solitary Bone Metastasis of Lung Cancer.

Radiation therapy plays an important role in the treatment of lung cancer. Although adverse effects of radiation are well known, they are sometimes difficult to be diagnosed. We report a case of a radiation-associated vertebral compression fracture which mimicked bone metastasis of lung cancer. The patient was a 57-year-old man diagnosed with lung squamous cell carcinoma (cT1aN2M0, c-stage IIIA). He received concurrent chemoradiotherapy (CRT) in combination with 6 weeks of weekly carboplatin plus paclitaxel and thoracic radiation of 60 Gy/30 fractions, followed by bi-weekly durvalumab for 12 months. On the last day of the 12-month durvalumab regimen, he complained of backache. Magnetic resonance imaging showed compression fracture of the seventh thoracic vertebra with the spinal cord compressed, and fluorine-18 fluorodeoxyglucose positron emission tomography and computed tomography demonstrated weak focal uptake only at the seventh thoracic vertebra. Although the fracture had been suspected to be bone metastasis, surgical biopsy revealed no evidence of malignancy. Since the seventh thoracic vertebra was included in the irradiation area, the patient was diagnosed with a radiation-associated fracture. Dual-energy X-ray absorptiometry of the lumbar vertebrae (L2 - 4) after the surgery revealed osteopenia. In conclusion, we successfully diagnosed the radiation-associated vertebral fracture caused by radical CRT. The fracture mimicked bone metastasis in preoperative imaging tests. Thus, surgical biopsy was useful for diagnosis.

Successful Dasatinib Treatment of Epidermal Growth Factor Receptor-Mutant Lung Adenocarcinoma and BCR-ABL1-Positive Chronic Myeloid Leukemia: A Case Report.

Dasatinib, a second-generation BCR-ABL1 tyrosine kinase inhibitor (TKI), inhibits multiple kinase pathways and is a promising anti-tumor agent for various solid tumors, including lung cancer. Herein, we report a patient with coexisting epidermal growth factor receptor (EGFR)-mutant lung adenocarcinoma and BCR-ABL1-positive chronic myeloid leukemia (CML). The patient received afatinib for a postoperative intrapulmonary recurrence of lung adenocarcinoma harboring EGFR exon 19 deletion. Tumor reduction was achieved with afatinib; however, dose reduction was required because of grade 2 diarrhea and skin toxicity. The reduced dose maintained a partial response. Thirty-one months after introduction of afatinib, he was diagnosed as having BCR-ABL1-positive CML and nilotinib was added to his treatment regimen. However, the combination of nilotinib and afatinib aggravated his diarrhea, prompting discontinuation of afatinib. Because nilotinib does not have sufficient anti-tumor efficacy for CML, dasatinib was substituted for nilotinib. Thirty-five months after introduction of dasatinib, bosutinib was substituted for dasatinib because of uncontrollable pleural effusions. Dasatinib achieved 31- and 35-month progression-free survivals for CML and EGFR-mutant lung adenocarcinoma, respectively. Dasatinib is thus a therapeutic option for coexisting EGFR-mutant lung adenocarcinoma and BCR-ABL1-positive CML when TKI combination therapy is contraindicated by severe adverse events. In our patient, adding nilotinib to afatinib led to severe diarrhea. When administering TKI combination therapy, drug-drug interactions should be considered.

The prognostic significance of human equilibrative nucleoside transporter 1 expression in patients with metastatic bladder cancer treated with gemcitabine-cisplatin-based combination chemotherapy.

OBJECTIVE: To evaluate the expression of the human equilibrative nucleoside transporter 1 (hENT1) and excision repair cross complementing 1 (ERCC1) as possible prognostic factors for patients with metastatic bladder cancer treated with gemcitabine-cisplatin-based combination chemotherapy. PATIENTS AND METHODS: The present study retrospectively evaluated the expression of hENT1 and ERCC1 by immunostaining in chemo-naive primary bladder tumour specimens from 40 patients with metastatic bladder cancer who received treatment with gemcitabine-cisplatin-based combination chemotherapy at Wakayama Medical University Hospital and affiliated hospitals from May 2002 to July 2009. Immunohistochemistry on formalin-fixed, paraffin-embedded tissues was performed with specific hENT1 and ERCC1 antibodies scored by two pathologists who were blinded to clinical outcomes. The clinical and histopathological variables were analyzed to evaluate predictive values for survival. RESULTS: The median survival time in patients with high and low hENT1 expression was 17.3 and 11.6 months, respectively (log-rank test, P = 0.003). This contrasted with the median survival in patients with high and low ERCC1 expressions, which did not differ significantly (high ERCC1, 13.6 months; low ERCC1, 17.1 months; P = 0.178). In univariate Cox regression analyses for pretreatment clinicopathological variables, performance status (P = 0.02) and hENT1 expression (P = 0.004), but not ERCC1 expression (P = 0.182), were associated with overall survival. Multivariate analysis using a Cox proportional hazards model showed that hENT1 expression was an independent prognostic factor (P = 0.008). CONCLUSION: The data obtained in the present study show that high expression of hENT1 in tumour cells is associated with prolonged survival in patients with metastatic bladder cancer treated with gemcitabine-cisplatin-based combination chemotherapy.

[A case of metastatic pulmonary cancer from urachal carcinoma that required differentiation from primary lung adenocarcinoma].

A 58-year-old man was given a diagnosis of urachal carcinoma and underwent a partial cystectomy with enbloc removal of the tumor and radical lymphadenectomy in 2006. In April 2009 he was admitted to our hospital because of hemoptysis and left chest pain. Chest CT showed a 4-cm mass shadow in the left S3 and nodular shadows in the right S1 and left S10. Flexible bronchoscopy demonstrated a tumorous lesion at the orifice of the left B3 bronchus. Although the cytological diagnosis suggested high-grade adenocarcinoma, the tumor was producing mucin and consisted of cells with anisonucleosis, which is not typical of primary lung adenocarcinoma. We then performed immunohistochemical and histological examination of a transbronchial lung biopsy specimen. The histological findings of the specimen were very similar to those of the previously resected urachal carcinoma. In addition, the tumor cells were negative for thyroid transcription factor-1 and surfactant precursor protein B, which are specific to primary lung adenocarcinoma. We therefore diagnosed metastatic pulmonary cancer from urachal carcinoma, which is a rare manifestation in bladder cancer. We report a rare case of metastatic pulmonary cancer from urachal carcinoma that required differentiation from primary lung adenocarcinoma in addition to a discussion of the literature.

Transformation From Adenocarcinoma to Pleomorphic Carcinoma as an Acquired Resistance to Epidermal Growth Factor Receptor Tyrosine Kinase Inhibitors.

Pulmonary pleomorphic carcinoma is a very rare histological type of primary lung cancer, and usually provides aggressive clinical courses. A 65-year-old Japanese woman was diagnosed by transbronchial biopsy of the primary tumor as c-stage IV (cT4N3M1b) of adenocarcinoma harboring L858R point mutation in the exon 21 of epidermal growth factor receptor (EGFR). She received EGFR tyrosine kinase inhibitors (TKIs) (gefitinib and erlotinib) and subsequently cytotoxic chemotherapies. Gefitinib achieved partial response, but was switched to erlotinib due to elevated serum aspartate transaminase. After resistance to EGFR-TKIs, the second transbronchial re-biopsy revealed pulmonary pleomorphic carcinoma. Both carcinomatous and sarcomatous components retained the L858R mutation, but did not acquire T790M mutation. This case suggested that the histological transformation to pulmonary pleomorphic carcinoma may be one of mechanisms of drug resistance to EGFR-TKIs.

Pulmonary Adenosquamous Cell Carcinoma With Systemic Lymphadenopathy due to Immunoglobulin G4-Related Disease: A Case Report.

A 75-year-old man with diabetes mellitus showed elevated C-reactive protein (CRP) level at his regular visit. Computed tomography scan showed a lung tumor in his left lower lobe and systemic lymphadenopathy including abdominal lymph nodes. The patient was diagnosed as primary pulmonary squamous cell carcinoma with systemic lymph node metastasis. Thereafter, unexpected steroid pulse therapy for accidental acute exacerbation of interstitial pneumonia rapidly shrank lymphadenopathy. At this time, we also found elevated serum immunoglobulin G4 (IgG4) level (385 mg/dL). Considering these findings, we doubted the lymph nodes metastases at the initial staging, and then corrected cancer-staging (C-staging) from inferior vena cava (IVC) to inferior abdomen (IA). In addition, during the steroid tapering, sudden onset and uncontrollable left pneumothorax required surgical approach. Curative-intent left lower lobectomy with lymphadenectomy was performed for the lung cancer. Pathological findings revealed coexistence of adenosquamous carcinoma and infiltration of IgG4-positive plasma cells in the resected mediastinal lymph node. We detected 384 IgG4-positive cells per high power field. IgG4/IgG-positive cell ratio was 54%. Based on these findings, the diagnosis of IgG4-related disease with primary adenosquamous carcinoma (p-stage IIIA) was confirmed. The patient died 24 days after surgery because of another acute exacerbation of interstitial pneumonia. Our case alerts oncologists to IgG4-related disease as a possible underlying comorbidity which may confuse pretreatment clinical stage.

Pigmented spindle cell variant of a thymic atypical carcinoid in an octogenarian.

BACKGROUND: A pigmented carcinoid is an extremely rare variant of carcinoid characterized by melanin pigmentation of the tumor, with only five cases described in the literature. In addition, thymic carcinoids are rare in elderly patients and their prognosis after resection of the carcinoid tumor is unclear. CASE PRESENTATION: An anterior mediastinal tumor was incidentally found in an 82-year-old man who had been diagnosed with acute thoracic empyema. The tumor was considered most likely to be a noninvasive thymoma or thymic carcinoma for which surgery was indicated after the resolution of the empyema. The tumor was completely resected 4 months after the empyema surgery, and the patient had an uneventful postoperative course. A cut surface of the resected specimen was extensively pigmented and appeared dark-brownish, with abundant melanin pigmentation later confirmed in the spindle-shaped tumor cells. Based on the histologic examination and immunohistochemical study, melanoma was eliminated as a differential diagnosis and the tumor was diagnosed as a pigmented atypical carcinoid of the thymus. CONCLUSIONS: This report provides additional knowledge on thymic pigmented carcinoids and thymic atypical carcinoids in elderly patients.

Pembrolizumab-Induced Meningoencephalitis: A Brain Autopsy Case.

Encephalitis is very rare, but often fatal immune-related adverse event (irAE) of immune checkpoint inhibitors (ICIs). A 65-year-old Japanese woman was admitted to our hospital because of general fatigue, chillness and high-grade fever for 4 days, 8 months after the initiation of the first-line pembrolizumab monotherapy for metastatic pulmonary adenocarcinoma. On the hospital day 3, she suddenly presented delirium and uncontrollable impaired consciousness. Although the magnetic resonance imaging (MRI) did not suggest a diagnosis of encephalitis and meningitis, the spinal fluid showed abnormally elevated levels of protein (317.6 mg/L) and cell count (197 cells/µL) with increased mononuclear cells (93%). An empirical and intravenous administration of acyclovir in doses of 10 mg/kg body weight every 8 h and steroid pulse therapy in dose of 1 g/body/day from the hospital day 5 until her death failed to improve her conditions. She died on the hospital day 8. The postmortem autopsy showed viable cancer cells in the metastatic tumor in the left occipital lobe and in the spinal fluids. However, many inflammatory cells infiltration in the meninges and perivascular cuffing were prominent especially in the brain stem and medial part of the temporal lobe. Infiltrating lymphocytes in the meninges and parenchyma of the brain stem were mainly composed of cluster of differentiation (CD)8-positive lymphocytes. For irAE encephalitis, early recognition of early signs and symptoms and subsequent early therapeutic intervention are necessary. It is important for oncologists to keep in mind of the possible adverse effects of immunotherapies on the nervous system.