Thymoma Exhibiting Spontaneous Regression With Cystic Change Due to Acute Infarction: A Case Report and Literature Review.

Spontaneous regression (SR) of thymoma is rare. We report a case of a surgically resected thymoma due to cystic changes owing to acute ischemic infarction with an increased anti-acetylcholine receptor antibody level. A 61-year-old male underwent a computed tomography (CT) scan, which showed a 4.9 cm anterior mediastinal tumor and slight right pleural effusion. Blood test results indicated an elevated white blood cell count of 13300/mL. One month later, an enhanced CT scan at our hospital showed spontaneous mediastinal tumor regression to 3.7 cm and no pleural effusion. The tumor contained homogeneous low-density areas on enhanced CT, which showed high intensity on T2-weighted magnetic resonance imaging, indicating cystic changes. He had no symptoms of myasthenia; however, his anti-acetylcholine receptor antibody level was slightly elevated (0.4 nmol/L). Suspecting a thymoma, an extended total thymectomy through a median sternotomy was performed. Histopathological analysis confirmed the diagnosis of thymoma type B2 and Masaoka stage I. SR is due to acute intratumoral infarction. At two years postoperatively, no tumor recurrence or development of myasthenia gravis was observed. Thymomas should be included in the differential diagnosis of anterior mediastinal tumors that regress spontaneously with cystic changes, pleural effusion, and an elevated inflammatory response. Mature cystic teratoma rupture should be differentiated, but preoperative biopsy is often challenging owing to necrotic and fibrous tissues; therefore, early surgical resection is required for diagnosis and treatment.

[Surgically Resected Cases of Mediastinal Ganglioneuroma Detected in Adults].

A ganglioneuroma is a rare, benign, neurogenic tumor originating from the sympathetic ganglion. Mediastinal ganglioneuroma are mostly detected in children, typically around 10 years of age, and are rarely identified in adults. Herein, we report two surgically resected cases of mediastinal ganglioneuroma in adults. In Case 1, a 53-year-old man, without any symptom, underwent a computed tomography, revealing a 3.2 cm well-defined paravertebral superior mediastinal tumor with long craniocaudal axis. In case 2, a 29-year-old woman presented with newly-developed ptosis and a history of left-sided facial hypohidrosis since the age of 10. Chest computed tomography (CT) revealed a 7.8 cm well-defined paravertebral superior mediastinal tumor with long craniocaudal axis. Both patients were initially suspected to have neurogenic tumors, particularly schwannomas. They underwent mediastinal tumor resections, requiring sympathetic nerve trunk dissection. Pathological examination confirmed the diagnosis of ganglioneuromas in both cases. Mediastinal ganglioneuroma must be differentiated from schwannoma, the most common neurogenic tumor in adults. Unlike schwannoma, ganglioneuroma cannot be enucleated, therefore attention should be focused on complications associated with sympathetic nerve trunk dissection, such as Horner's syndrome, hyperhidrosis, and arrhythmia. Identifying this rare entity and its characteristic imaging aids in preoperative differentiation, strategizing surgical approaches, and predicting complications.

Recurrent GATA3 P409Afs*99 Frameshift Extension Mutations in Sweat-gland Carcinoma With Neuroendocrine Differentiation.

Sweat-gland carcinoma with neuroendocrine differentiation (SCAND) was recently proposed as a new cutaneous adnexal neoplasm with neuroendocrine differentiation; however, its genetics are not well known. Herein, we performed clinicopathologic and genetic analyses of 13 SCAND cases and 5 control cases of endocrine mucin-producing sweat gland carcinoma (EMPSGC). The SCAND group included 11 males and 2 females with a median age of 68 years (range, 50 to 80 y). All SCAND lesions occurred in the ventral trunk or genital area. Of the 13 SCAND cases, 9 and 5 exhibited lymph node and distant metastases, respectively. Three (23.1%) patients with SCAND died of the disease. In contrast, neither metastasis nor mortality was confirmed in the EMPSGC cases. Immunoexpression of the androgen receptor, c-Myb, and MUC2 was limited in SCAND, whereas EMPSGC frequently expressed these immunomarkers. GATA3 P409Afs*99 extension mutations were detected in 7 (53.8%) of the 13 SCAND cases, using Sanger or panel sequencing. All 7 SCAND cases with GATA3 mutations were located in the genital, inguinal, or lower abdominal regions, whereas 5 of the other 6 SCAND cases were located in the anterior upper to mid-trunk. No GATA3 mutations were detected in the EMPSGC cases (0/5, 0%). These clinicopathologic and genetic findings support SCAND as a tumor entity distinguishable from EMPSGC. In addition, the characteristic frameshift extension mutations in GATA3 contribute to the establishment of the tumor-type concept of SCAND.

Atypical type A thymoma component identified by pulmonary metastasectomy 11 years after surgery of type AB thymoma.

Atypical type A thymomas exhibit more aggressive features than conventional type A thymomas. Type AB thymomas rarely have atypical type A components. We report a rare case of type AB thymoma with an atypical type A component, that was identified after pulmonary metastasectomy 11 years after the primary surgery and long-term follow-up after recurrence. A 61-year-old female underwent extended thymectomy for an anterior mediastinal tumor 11 years prior and was diagnosed with type AB thymoma (Masaoka stage II). Five years ago, follow-up computed tomography showed well-circumscribed pulmonary nodules up to 1.0 cm in both lungs. All the pulmonary nodules grew slowly; however, one of the nodules grew to 1.6 cm, and thoracoscopic wedge resection was performed for diagnosis. Pathologically, the pulmonary nodule was consisted of type A thymoma component. Conventional type AB thymomas are usually locally aggressive neoplasms; thus, we reviewed the tissue slides of primary thymomas. Histologically, cytological atypia, hypercellularity, and increased mitosis are observed in the type A component. Consequently, the diagnosis was revised to a type AB thymoma with an atypical type A component. The pulmonary nodule exhibited the same atypical type A features. Pulmonary metastasectomy was performed two more times as volume-reduction surgery. The residual metastasis was located only in the lung with slow growth, 4 years after the first pulmonary resection; therefore, we followed up as an outpatient without treatment.

KDM2B-Rearranged Soft Tissue Sarcomas Expand the Concept of BCOR-Associated Sarcoma.

Sarcomas with BCOR genetic alterations (BCOR-associated sarcomas) represent a recently recognized family of soft tissue and bone tumors characterized by BCOR fusion, BCOR internal tandem duplication, or YWHAE::NUTM2B fusion. Histologically, the tumors demonstrate oval to spindle cell proliferation in a variably vascular stroma and overexpression of BCOR and SATB2. Herein, we describe 3 soft tissue sarcomas with KDM2B fusions that phenotypically and epigenetically match BCOR-associated sarcomas. The cases included 1 infant, 1 adolescent, and 1 older patient. All tumors showed histologic findings indistinguishable from those of BCOR-associated sarcomas and were originally diagnosed as such based on the phenotype. However, none of the tumors had BCOR or YWHAE genetic alterations. Instead, targeted RNA sequencing identified in-frame KDM2B::NUTM2B, KDM2B::CREBBP, and KDM2B::DUX4 fusions. KDM2B fusions were validated using reverse-transcription PCR, Sanger sequencing, and in situ hybridization assays. Genome-wide DNA methylation analysis matched all 3 tumors with BCOR-associated sarcomas using the Deutsches Krebsforschungszentrum (DKFZ) classifier and t-distributed stochastic neighbor embedding analysis. One localized tumor showed a flat genome-wide copy number profile, and the patient remained disease-free after treatment. The other tumors showed multiple copy number alterations, including MDM2/CDK4 amplification and/or CDKN2A/B loss, and both tumors metastasized, leading to the patient's death in one of the cases. When tested using KDM2B immunohistochemistry, all 3 KDM2B-rearranged sarcomas showed diffuse strong staining, and all 13 sarcomas with BCOR genetic alterations also demonstrated diffuse, strong, or weak staining. By contrast, among 72 mimicking tumors, only a subset of synovial sarcomas showed focal or diffuse weak KDM2B expression. In conclusion, our study suggests that KDM2B-rearranged soft tissue sarcomas belong to the BCOR-associated sarcoma family and expand its molecular spectrum. This may be related to the known molecular relationship between KDM2B and BCOR in the polycomb repressive complex 1.1. Immunohistochemical analysis of KDM2B is a potentially valuable diagnostic tool for BCOR-associated sarcomas, including those with KDM2B rearrangement.

Molecular insights of a CBP/ß-catenin-signaling inhibitor on nonalcoholic steatohepatitis-induced liver fibrosis and disorder.

Nonalcoholic steatohepatitis (NASH) is a progressive fibrotic disease associated with an increased risk of developing hepatocellular carcinoma; at present, no efficient therapeutic strategy has been established. Herein, we examined the efficacy of PRI-724, a potent inhibitor of CBP/ß-catenin signaling, for treating NASH-related liver fibrosis and disorder and characterized its mechanism. Choline-deficient, L-amino acid-defined, high-fat diet (CDAHFD)-fed mice exhibited NASH-induced liver fibrosis that is characterized by steatosis, lobular inflammation, hepatocellular injury and collagen fibrils. To examine the therapeutic effect, CDAHFD-fed mice were administered PRI-724. Serum levels of ALT and pro-fibrotic molecule, i.e. Mac-2 bp, alpha smooth muscle actin, type I and type III collagens, decreased significantly. mRNA levels of the matrix metalloproteinases Mmp8 and Mmp9 in the liver were significantly increased, and increases in the abundance of MMP9-producing neutrophils and macrophages were observed. Marco+Mmp9+Cd68+ Kupffer cells were only observed in the livers of mice treated with PRI-724, and Mmp9 expression in Marco+Cd68+ Kupffer cells increased 4.3-fold. Moreover, hepatic expression of the lipid metabolism regulator, pyruvate dehydrogenase kinase 4 and liver lipid droplets also decreased significantly. PRI-724-treated NASH mice not only recovered from NASH-related liver fibrosis through the effect of PRI-724 down-regulating the expression of pro-fibrotic genes and up-regulating the expression of anti-fibrotic genes, but they also recovered from NASH-induced liver disorder. PRI-724, a selective CBP/ß-catenin inhibitor, thus shows a potent therapeutic effect for NASH-related liver fibrosis and for decreasing adipose tissue in the liver.

Successful Treatment of ALK-Positive Large-Cell Neuroendocrine Carcinoma of the Lung With Sequential ALK Inhibitors: A Case Report.

ALK-positive large-cell neuroendocrine carcinoma (LCNEC) is an exceptionally rare form of lung cancer. The efficacy of ALK inhibitors in treating ALK-positive LCNEC remains unclear. Here, we report a case of ALK-positive LCNEC of the lung, which revealed a sustained clinical benefit (24+ mo of overall survival) after treatment with sequential ALK inhibitors and local therapies. This remarkable improvement in survival underscores the importance of testing metastatic LCNEC for biomarkers, such as ALK rearrangement, using immunohistochemistry or next-generation sequencing, especially in younger patients.

Multifocal Cholesterol Granulomas of the Thymus: A Case Report of Positron Emission Tomography- Positive Benign Tumor of the Anterior Mediastinum.

Cholesterol granulomas of the thymus are extremely rare benign entities. Herein, we describe a case of cholesterol granuloma in a 45-year-old man who presented with multifocal anterior mediastinal lesions on computed tomography (CT). Positron emission tomography (PET)-CT revealed increased fluorodeoxyglucose uptake, with a maximum standardized uptake value of 8.3. Diffusion-weighted magnetic resonance imaging (MRI) revealed extreme hypointensity. He underwent total thymectomy by median sternotomy for presumed multiple thymoma. On histopathological analysis, cholesterol granuloma of the thymus was confirmed, and the patient had an uneventful postoperative course without recurrence for 28 months. Cholesterol granuloma of the thymus is a PET-CT-positive benign tumor with unique histological findings. The MRI findings were indicative of hypocellularity associated with a benign entity, whereas the PET-CT findings corresponded to granulomatous inflammation. Therefore, concurrent use of PET-CT and MRI can be helpful in distinguishing between benign cholesterol granulomas and malignant anterior mediastinal tumors.

Seborrheic Keratosis With Malignant Transformation (Invasive or Noninvasive Squamous Cell Carcinoma Arising in Seborrheic Keratosis): A Clinicopathologic and Immunohistochemical Study of 11 Cases.

ABSTRACT: Seborrheic keratosis is a common benign neoplasm composed of basaloid keratinocytes. However, little is known about the malignant transformation of the tumor. Eleven cases of seborrheic keratosis with malignant transformation were analyzed. The 11 patients included 5 male patients and 6 female patients with a median age of 75 years at diagnosis (68-90 years). The tumors arose at various sites from the scalp (n = 3) to the lower leg (n = 2). The median tumor size was 12 (10-32) and 40 (20-75) mm in 7 noninvasive and 4 invasive cases, respectively. One patient exhibited in-transit skin metastasis. Histopathology of the malignant components resembled porocarcinoma or inverted follicular keratosis. Bowenoid and pagetoid spreading was frequently observed. The malignant components expressed cytokeratin 5/6 (100%) and GATA3 (73%), but not cytokeratin 7 (0%), cytokeratin 19 (9%), BerEP4 (0%), c-kit (0%), and NUT (0%). No significant immunoreactivity of YAP1 was observed in any of the cases. Mutant-type immunostaining of p53 and PTEN was observed in 91% and 82% of the cases, respectively. An increase in p16 expression was seen in 6 (86%) of the 7 cases with noninvasive carcinoma, although a loss of p16 immunoexpression was seen in the invasive carcinoma component in 3 (75%) of the 4 cases. This study demonstrated that seborrheic keratosis can undergo malignant transformation, particularly in large-sized lesions in elderly patients. Malignant components mimic porocarcinoma or inverted follicular keratosis. Malignant transformation induced by TP53 and PTEN mutations and tumor invasion by CDKN2A inactivating mutations are suggested in this study.

Central nervous system mucormycosis in a patient with hematological malignancy: A case report and review of the literature.

Invasive mucormycosis is a refractory fungal infection. Central nervous system (CNS) mucormycosis is a rare complication caused by infiltration from the paranasal sinuses or hematogenous dissemination. Here, we present a case of a brain abscess, due to mucormycosis, diagnosed using burr craniotomy. A 25-year-old Japanese woman with relapsed-refractory acute lymphoblastic leukemia underwent cord blood transplantation (CBT). The patient experienced prolonged and profound neutropenia, and oral voriconazole was administered as primary antifungal prophylaxis. The patient received a conditioning regimen on day -11 and complained of aphasia and right hemiparesis on day -6. Magnetic resonance imaging (MRI) revealed a T2-weighted high-intensity area in the left frontal cortex. A brain abscess was suspected, and liposomal amphotericin B (L-AMB) administration was started. The patient underwent CBT as scheduled and underwent neutrophil engraftment on day 14. Although the patient achieved complete remission on day 28, her consciousness level gradually deteriorated. MRI revealed an enlarged brain lesion with a midline shift sign, suggesting brain herniation. Craniotomy was performed to relieve intracranial pressure and drain the abscess on day 38, and a diagnosis of cerebral mucormycosis was confirmed. The L-AMB dose was increased to 10 mg/kg on day 43. Although the patient's consciousness level improved, she died of hemorrhagic cystitis and aspiration pneumonia. Cerebral mucormycosis should be suspected if neurological symptoms are observed in stem cell transplant recipients. Prompt commencement of antifungal therapy and debridement are crucial because mucormycosis has a poor prognosis.

Pulmonary metastasis of matrix-producing carcinoma mimicking small cell lung cancer.

Matrix-producing carcinoma (MPC) of the breast is an extremely rare subtype of invasive breast cancer. MPC is characterized by the production of a cartilaginous or osseous matrix without spindle cells. It is an aggressive carcinoma, often presenting as triple-negative breast cancer. MPC frequently metastasizes to the lungs; however, it rarely reoccurs as a solitary pulmonary metastasis. We report a case of a 77-year-old non-smoking woman with a solitary pulmonary metastasis of MPC, which mimicked small cell lung cancer (SCLC). Initially, the pulmonary metastasis was misdiagnosed as SCLC based on its morphological and immunochemical features, including focal positivity for CD56 and thyroid transcription factor-1. Although the portion of the chondromyxoid matrix of the primary site was not small, that of the metastatic site was small. A focal cartilaginous matrix deposition of pulmonary metastasis from MPC could make it difficult to differentiate from SCLC. We should acknowledge that the portion of chondromyxoid matrix may differ between primary and distant metastatic sites in MPC.

Thymoma exhibiting spontaneous regression with developing myasthenia gravis: A case report.

Spontaneous regression (SR) of thymoma is rare. A 44-year-old man with right chest pain underwent computed tomography (CT), which showed an 11.0 cm mass in the anterior mediastinum and right pleural effusion. He refused surgery and was sent home without medication and additional treatment. One year later, the mass had regressed to 5.5 cm, and the right pleural effusion had disappeared. He was then lost to follow-up. Four years after the initial visit, he presented with diplopia and fatigue. A significant increase in his anti-acetylcholine receptor antibody levels led to myasthenia gravis (MG) diagnosis. CT revealed a regressed mediastinal mass (3.0 cm). After extended thymectomy, histologic analysis confirmed a thymoma type B2, Masaoka stage IIa. The SR was due to intratumoral infarction. This report is the first to describe MG developing during SR. Anterior mediastinal tumors undergoing SR should be differentiated from thymomas and MG perioperative development should be considered.

Intracranial complete response for non-small-cell lung cancer patient with negative PD-L1 expression of the lung using nivolumab.

BACKGROUND: Nivolumab has shown promising results against non-small-cell lung cancer (NSCLC). However, its efficacy to treat central nervous system (CNS) metastases, specifically among programmed cell death 1 ligand 1 (PD-L1)-negative patients, remains unclear. CASE: A 66-year-old woman was diagnosed with adenocarcinoma stage II and underwent a left lower lobectomy. The histopathological evaluation revealed stage IVA with pleural dissemination. The patient did not harbor an epidermal growth factor receptor (EGFR) mutation or anaplastic lymphoma kinase (ALK) rearrangement, and PD-L1 expression of the surgical specimen using 22C3 assay was 0%. Single brain metastasis was detected, and carboplatin and nab-paclitaxel were administered. After three cycles, asymptomatic multiple brain metastases were identified, and the patient was treated with nivolumab as second-line chemotherapy. Six months later, MRI revealed an intracranial complete response (CR). Nivolumab was discontinued after 23 cycles due to immune-related adverse events (irAEs) of grade 2 rash. However, its effects were sustained for 13 months after discontinuation. We were unable to evaluate the PD-L1 expression of brain metastases, which may show heterogeneity. CONCLUSION: This case demonstrates that nivolumab effectively treated a patient with negative PD-L1 expression of the lung harboring CNS metastases.

Sweat-gland carcinoma with neuroendocrine differentiation (SCAND): a clinicopathologic study of 13 cases with genetic analysis.

Low-grade neuroendocrine carcinoma of the skin (LGNECS) was proposed in 2017 as a new primary cutaneous neoplasm with neuroendocrine differentiation; however, it is not yet well known due to its rarity. Herein, we perform a detailed clinicopathologic analysis of 13 cases as well as panel DNA sequencing in three cases. The study included 12 males and 1 female with a median age of 71 (43-85) years. All lesions occurred on the ventral trunk. The mean tumor size was 2.2 (0.8-11.0) cm. The histopathology resembled that of well-differentiated neuroendocrine tumors (NETs) in other organs, but intraepidermal pagetoid spreading was seen in 8 (61.5%) cases and stromal mucin deposits in 4 (30.8%). Immunoreactivity for CK7, CK19, EMA, BerEP4, CEA, chromogranin A, synaptophysin, INSM1, GCDFP15, GATA3, ER, and bcl-2 were present in varying degrees in all tested cases. PTEN c.165-1G>A splice site mutation was detected by panel sequencing in one case, and GATA3 P409fs*99 and SETD2 R1708fs*4 in another case. Lymph node metastasis was seen significantly in cases with tumor size >2.0 cm [8/8 (100%) vs. 1/5 (20%)]. All three cases with size >3.0 cm were in unresectable advanced-stage [3/3 (100%) vs. 1/10 (10%)], and two of the three patients succumbed to the disease. The two cases of death revealed mild nuclear atypia (mitosis: 1/10 HPFs) and moderate nuclear atypia (2/10 HPFs). Thus, tumor size would be a better prognostic factor than nuclear atypia, mitotic count, and Ki67 index, unlike in NETs. These clinicopathologic and immunohistochemical features would represent the characteristics as skin adnexal tumors with apocrine/eccrine differentiation rather than NETs; therefore, we rename it as sweat-gland carcinoma with neuroendocrine differentiation (SCAND).

A case of diffuse pulmonary ossification.

Diffuse pulmonary ossification (DPO) is a rare condition characterized by the formation of bone tissues in the lung. DPO is considered to be accompanied by chronic lung diseases, such as idiopathic interstitial pneumonitis or chronic obstructive pulmonary disease, acute respiratory distress syndrome, or inhalation-related lung diseases. Most reported cases of DPO were diagnosed during autopsies or surgical specimen. We report a case of DPO after kidney transplantation diagnosed by transbronchial lung biopsy.

Signet-ring cell/histiocytoid carcinoma of the axilla: a clinicopathological and genetic analysis of 11 cases, review of the literature, and comparison with potentially related tumours.

AIMS: The aim of this study was to determine the clinicopathological and genetic characteristics of axillary signet-ring cell/histiocytoid carcinoma (SRCHC) and the relationship between axillary SRCHC, eyelid SRCHC, and conventional apocrine carcinoma (AC). METHODS AND RESULTS: Eleven cases of axillary SRCHC, four cases of eyelid SRCHC, eight cases of axillary AC and five cases of invasive lobular carcinoma (ILC) were retrieved. Additionally, 14 axillary and 43 eyelid SRCHC cases from the literature were reviewed. Male predominance was prominent for axillary SRCHC (24:1) and eyelid SRCHC (42:5). Axillary SRCHC formed a circumscribed plaque or nodule, unlike eyelid SRCHC. Lymph node metastasis was predominantly seen in axillary SRCHC cases (72%, 18/25), but not in eyelid SRCHC cases (19%, 9/47). Axillary SRCHC and eyelid SRCHC were histopathologically similar and showed rare tubular formations. Immunoexpression of cytokeratin 7, cytokeratin 19, mucin 1, mucin 5AC, BerEP4 and androgen receptor was seen in all tested cases of the four diseases. Oestrogen and progesterone receptors were negative in both types of SRCHC and AC, but were strongly positive in ILCs. Complete loss of E-cadherin expression was seen in approximately one-quarter of both types of SRCHC and in all ILCs. PIK3CA mutations were detected in all three sequenced cases (two axillary SRCHCs and one eyelid SRCHC). CONCLUSION: The histopathological, immunohistochemical and genetic findings suggest that both types of SRCHC are phenotypic variants of AC, although there are differences in sex, macroscopic findings and the frequency of lymph node metastasis among the three. In contrast, ILC differs from the other three tumour types.

Clinicopathological features of sporadic MSI colorectal cancer and Lynch syndrome: a single-center retrospective cohort study.

BACKGROUND: The clinical and pathological features of sporadic microsatellite instability-high (MSI) colorectal cancer (CRC) are still unclear. The present study aimed to clarify the clinicopathological features of sporadic MSI CRC in comparison with those of Lynch syndrome (LS) exploratorily. METHODS: The present study was a single-center, retrospective cohort study. Sporadic MSI CRC was defined as MSI CRC with aberrant promoter hypermethylation of the MLH1 gene, while hereditary MSI CRC was defined colorectal cancer in patients with LS. RESULTS: In total, 2653 patients were enrolled; of these, 120 (4.5%) had MSI CRC, 98 had sporadic MSI CRC, and 22 had LS. Patients with sporadic MSI CRC were significantly older (p < 0.001) than those with LS and had a right-sided colonic tumor (p < 0.001) which was pathologically poorly differentiated or mucinous (p = 0.025). The overall survival rate was significantly lower in patients with stage I, II or III MSI CRC than in those with LS (p = 0.024). However, the recurrence-free survival rate did not differ significantly (p = 0.85). CONCLUSIONS: We concluded that patients with sporadic MSI are significantly older, tumors more likely to locate in the right-sided colon, pathologically poorly differentiated or mucinous, and worse overall survival than in those with LS.

Feasibility of intraoperative diagnosis of lung adenocarcinoma in situ to avoid excessive resection.

BACKGROUND: Limited lung resection is generally believed to be available for lung adenocarcinoma in situ (AIS). At our institute, intraoperative hematoxylin-eosin staining of frozen-section slides is routinely performed for evaluating tumor invasiveness after partial resection to avoid excessive lung resection. This study aimed to evaluate the feasibility and usefulness of intraoperative frozen-section diagnosis of AIS. METHODS: We retrospectively reviewed 143 patients with 151 AISs diagnosed by intraoperative frozen sections between 2012 and 2019 at our institute. All patients underwent limited resection because of the result of intraoperative frozen-section diagnosis. RESULTS: The total concordance rate between the diagnoses of AIS by intraoperative frozen sections and postoperative paraffin-embedded sections was 82.7% for 151 nodules. Although 21 minimally invasive adenocarcinomas (MIA) and 5 invasive adenocarcinomas were diagnosed as AIS intraoperatively, no patient had tumor recurrence after resection. Among 125 pathologically proven cases of AIS postoperatively, there were 67 (53.6%) radiologically invasive tumors including ground-glass nodules (GGNs) with part-solid component or pure-solid nodules. CONCLUSIONS: This intraoperative evaluation of frozen-section slides will help surgeons avoid excessive lung resection for AIS that was radiologically diagnosed as invasive adenocarcinoma. Intraoperative frozen-section diagnosis will provide to be clinically useful and lead to less invasive surgical treatment for lung nodules.

CT imaging findings of anti-PD-1 inhibitor-related enterocolitis.

PURPOSE: Immune checkpoint inhibitors promote the antitumor activity of T cells; however, there is a risk of side effects. The aim of this study was to characterize the computed tomography (CT) findings of one such side effect, anti-programmed cell death-1 antibody-related enterocolitis (αPD-1-EC). METHODS: This single-institution retrospective study included 21 patients with αPD-1-EC who underwent CT between January 2015 and April 2020. Two board-certified radiologists independently evaluated the CT findings, including the pattern of intestinal wall enhancement, maximum bowel wall thickness, maximum appendiceal diameter, and involvement of enterocolitis in each intestinal segment. Symptoms and their severity were also investigated. RESULTS: Pancolitis and skip lesions involving both the rectosigmoid colon and the cecum were found in 9 patients each (42.9%). The rectum was the most frequently involved lesion (18/21, 85.7%), and appendiceal involvement was found in 11 patients (52.4%). The most frequent wall enhancement pattern was the gray pattern (i.e., mild homogeneous enhancement of the thickened bowel wall). The mean maximum diameter of the involved appendix was 9.6 ± 4.5 mm (range 4.5-18 mm). Frequent symptoms included diarrhea (21/21), fever (8/21), and abdominal pain (7/21). Other concomitant immune-related adverse events were found in 6 patients. CONCLUSIONS: Pancolitis, skip lesions, and appendiceal involvement were frequent in patients with αPD-1-EC. When combining these characteristic findings with other clinical findings, such as low-grade diarrhea, other concomitant immune-related adverse events, and anti-PD-1 therapy administration, CT may be a useful diagnostic tool for αPD-1-EC.