Langerhans Cell Histiocytosis With Unusual Hexagonal Crystals in Addition to Usual Charcot-Leyden Crystals. Report of a Patient With Possible Process of Crystal Formation and Clinical Significance of a "Necrotic" Change.

Langerhans cell histiocytosis is a rare neoplastic disorder characterized by the proliferation of Langerhans cells and often accompanied by eosinophil infiltration. Charcot-Leyden crystals, composed of galectin 10, are occasionally observed in Langerhans cell histiocytosis; however, histological images are rarely reported. We herein present a patient with Langerhans cell histiocytosis with Charcot-Leyden crystals and hexagonal crystals by describing the histologic and immunohistochemical features of a lymph node. A unique distribution of Charcot-Leyden crystals and hexagonal crystals was observed in this patient, shedding light on their possible formation process of the latter. We discuss the biological significance of eosinophilic abscesses in Langerhans cell histiocytosis and propose that these crystals may be linked to extracellular trap-cell death (ETosis). This example challenges the conventional characterization of "necrosis" in Langerhans cell histiocytosis and underscores the importance of recognizing ETosis as a potential mechanism involved in the pathogenesis of Langerhans cell histiocytosis. Further studies are underway to validate significance of these findings in a larger cohort of Langerhans cell histiocytosis patients.

Recurrence of sarcoidosis accompanied by lung cancer after drug-induced pulmonary sarcoidosis with lung injury.

Sarcoidosis is a multisystemic granulomatous disease that is frequently localized in the lungs and lymph nodes. We herein report a case of pulmonary sarcoidosis secondary to shin'iseihaito administration. During remission with 5 mg prednisolone/day of maintenance treatment, chest computed tomography revealed a mass in the left lower lobe with re-enlarged bilateral hilar/mediastinal lymph nodes. Transbronchial lung biopsy of the mass and endobronchial ultrasound-guided transbronchial needle aspiration of mediastinal lymph nodes revealed adenocarcinoma and noncaseating granulomas, respectively. Based on these findings, the patient was diagnosed with sarcoidosis recurrence associated with lung cancer without cancer metastasis. We present the case of sarcoidosis recurrence associated with lung cancer after drug-induced pulmonary sarcoidosis with lung injury. To our knowledge, this is the first report of sarcoidosis triggered by drug administration and lung cancer. Histological diagnosis of mediastinal lymphadenopathy with lung cancer is essential for differentiating metastasis from sarcoidosis.

Numerous multinucleated giant cells in cutaneous epithelioid angiosarcoma and pulmonary metastasis: A unique observation with potential diagnostic pitfalls.

The histopathologic diagnosis of poorly differentiated cutaneous angiosarcoma can be challenging. We report a case of cutaneous epithelioid angiosarcoma with numerous multinucleated giant cells (MGCs) developing pulmonary metastasis. A 79-year-old man presented with a red-purple plaque on the scalp. A skin biopsy revealed epithelioid cell proliferation, admixed with numerous MGCs, and background hemorrhage. Vascular spaces were focally present and lined by atypical endothelial cells, including MGCs. Immunohistochemically, tumor cells, including MGCs, were positive for CD31, D2-40, and ERG. The patient received radiation therapy and chemotherapy, after which a follow-up CT scan revealed symptomless pneumothorax and pulmonary metastases. The patient received palliative partial lung resection, and the specimen revealed histopathological and immunohistochemical features similar to the primary cutaneous lesion. Our report expands the morphologic spectrum of cutaneous epithelioid angiosarcoma. Cutaneous angiosarcoma is an aggressive neoplasm; thus, awareness of this rare manifestation is important.

Methotrexate-associated lymphoproliferative disorder: A rare pancreatic tumor diagnosed via endoscopic ultrasound-guided fine-needle biopsy.

A 73-year-old woman with a history of rheumatoid arthritis treated with methotrexate (MTX) for the last 10 years was referred to our hospital for a pancreatic tumor examination. Contrast-enhanced abdominal computed tomography revealed a 20-mm-diameter hypovascular tumor in the pancreatic tail. A hypoechoic mass with heterogeneous internal echo was found on an endoscopic ultrasound (EUS). An EUS-guided fine-needle biopsy (EUS-FNB) was performed with a 22-gauge Franseen-tip needle. Histologic examination of EUS-FNB specimens from the pancreatic tumor revealed the proliferation of atypical spindle cells. Immunohistochemical staining for CD20 and Ki-67 was positive in the atypical cells. Immunohistochemical staining for CD3 was partially positive in the atypical cells. Epstein-Barr virus-encoded RNA in situ hybridization showed positive staining. MTX-related lymphoproliferative disorder (MTX-LPD) with Epstein-Barr virus infection was diagnosed. MTX treatment was immediately discontinued, and treatment was initiated by a hematologist. However, her condition rapidly deteriorated, and she died of multiple organ failure 4 weeks after diagnosis. MTX-LPD can complicate gastrointestinal lesions. However, most lesions are localized in the stomach and rarely complicate pancreatic lesions. MTX-LPD is classified as an "iatrogenic" LPD. Therefore, immediate action, such as MTX discontinuation, is necessary. In conclusion, endoscopists should be aware that MTX-LPD lesions can occur in the pancreas and gastrointestinal tract. Moreover, EUS-FNB can be useful in the diagnosis of this rare pancreatic tumor.

Awake Surgery for Angiocentric Glioma in the Eloquent Area in an Adolescent: A Case Report.

Angiocentric glioma (AG) is an extremely rare tumor that often develops in adolescents. Awake surgery for AG occurring in the eloquent area has not been reported to date. We report a case involving a right-handed 15-year-old boy with AG. He presented with a first-time generalized tonic-clonic seizure and was rushed to the local hospital. CT of the head indicated a left frontal low-density mass with no calcification. He was subsequently referred to our hospital. Comparison with a CT scan obtained two years prior due to mild head trauma indicated that the lesion showed a trend toward enlargement. The lesion was located in the anterior and lateral portions of the primary motor cortex, and MRI showed homogenous hypointensity on T1-weighted and hyperintensity on T2-weighted images. Contrast-enhanced MRI showed a linear contrast effect. The patient underwent awake surgery with successful intraoperative brain mapping and total resection, and brain function was preserved. Pathological analysis revealed AG. He returned to his normal life and has shown no recurrence without additional treatment for 2 years. Thus, awake surgery for complete tumor resection while preserving brain function is effective and safe even in adolescents with AGs.

Giant skull base periosteal chondroma treated with endonasal endoscopic surgery: illustrative case.

BACKGROUND: Intracranial chondroma is an extremely rare type of tumor composed of mature hyaline cartilaginous tissues. No previous cases of skull base periosteal chondroma have been presented. OBSERVATIONS: A 31-year-old male had progressive memory loss and diminished motivation for the previous 1.5 years. Magnetic resonance imaging revealed a giant tumor with partial calcification arising from the upper clivus and extending to the prepontine cistern. Compression of the brainstem and hypothalamus was significant. Surgery was performed and intentionally limited to an intracapsular resection with endoscopic endonasal surgery (EES), and the brainstem and hypothalamus were successfully decompressed. Pathological examination findings showed a composition of hyaline cartilage with chondrocyte clusters. Genetic testing with next-generation sequencing indicated alternations in IDH1 R132C, KDR Q472H, IDH2 I142L, and TP53 P72R. On the basis of these findings, a diagnosis of periosteal chondroma was made. Postoperatively, complete relief from all symptoms was noted, and MRI one year later showed no evidence of tumor regrowth. LESSONS: This is the first known report of skull base periosteal chondroma. Genetic testing was useful for confirming the diagnosis, and EES was effective for treatment. Should such a tumor show adhesion to an important structure, an intracapsular excision can be beneficial for avoiding complications.

Successful dabrafenib and trametinib combination therapy in a patient with recurrent BRAFV600E-mutant non-small-cell lung cancer and coexisting radiation pneumonitis.

There have been several reports of drug-induced lung injury caused by molecular-targeted agents. Additionally, medical history of interstitial lung disease and chest irradiation are established risk factors for the development and progression of drug-induced lung injury. Moreover, the presence of fibrosis on chest computed tomography before treatment is a predictive factor for the appearance of pneumonia induced by anticancer drugs. Accordingly, patients with a history of interstitial lung disease or pneumonitis were excluded from clinical trials of dabrafenib and trametinib combination therapy for patients with previously treated BRAF V600E-mutant metastatic non-small-cell lung cancer. This article presents a case of successful dabrafenib and trametinib combination therapy in a patient with BRAF V600E-mutant non-small-cell lung cancer who had a history of radiation pneumonitis and developed recurrence after conventional chemoradiotherapy.

POU2F3-Expressing Small Cell Lung Carcinoma and Large Cell Neuroendocrine Carcinoma Show Morphologic and Phenotypic Overlap.

Considering the differences in protein expression in small cell lung carcinoma (SCLC) by molecular classification, it is likely that there are differences in morphology, but the relationship between molecular classification and morphology has not been examined. Furthermore, there are limited reports concerning this molecular classification for large cell neuroendocrine carcinoma (LCNEC) and SCLC simultaneously. Therefore, we investigated the relationship between immunohistochemistry-based molecular classification and morphology, protein expression, and clinical features of 146 consecutive resection specimens of pulmonary neuroendocrine carcinoma (NEC), focusing mainly on POU2F3, the master transcription factor involved in tuft cell generation. POU2F3-dominant SCLC (n=24) and LCNEC (n=14) showed overlap in cytomorphology, while non-POU2F3-dominant SCLC (n=71) and LCNEC (n=37) showed distinct differences in cytomorphology. In addition, POU2F3-dominant NEC exhibited significantly more abundant tumor stroma, more prominent nest formation, more frequent bronchial intraepithelial involvement, and less frequent background fibrosis than non-POU2F3-dominant NEC. Immunohistochemically, POU2F3-dominant SCLC and LCNEC were characterized by lower expression of TTF-1, CEA, and neuroendocrine markers and higher expression of bcl-2, c-Myc, and c-kit. Clinically, POU2F3-dominant NEC had a significantly better prognosis than non-POU2F3-dominant NEC for recurrence-free survival. POU2F3-dominant NEC had a higher smoking index than non-POU2F3-dominant NEC. POU2F3-dominant NEC forms a unique population, exhibiting intermediate morphologic features between SCLC and LCNEC, with distinct protein expression as tuft cell-like carcinoma. Recognition of this unique subtype may provide clues for solving the long-standing issues of NEC and appropriate therapeutic stratification. It is important to accurately identify POU2F3-expressing carcinomas by immunohistochemistry and to analyze their clinicopathological features.

Implication of cytoplasmic p53 expression in pulmonary neuroendocrine carcinoma using next-generation sequencing analysis.

AIMS: Cytoplasmic p53 expression indicates a high frequency of TP53 abnormalities in gynaecological carcinoma. However, the implication of this expression in pulmonary neuroendocrine carcinoma (NEC) remains unclear. Thus, our study aimed to fill this research gap. METHODS AND RESULTS: Immunohistochemistry (IHC) of p53 was performed on 146 cases of resected small-cell lung carcinoma and large-cell NEC, and next-generation sequencing was conducted on cases showing cytoplasmic and wild-type p53 expression. IHC revealed overexpression in 57% of the cases (n = 83), complete absence in 31% (n = 45), cytoplasmic expression in 8% (n = 12) and wild-type expression in 4% (n = 6) of the cases. TP53 mutations were identified in nine of the 13 cases with available genetic analysis. The TP53 mutation rates in cases with cytoplasmic and wild-type p53 expression were 88% (seven of eight) and 40% (two of five), respectively. All seven cases showing cytoplasmic expression with TP53 mutations harboured loss-of-function type mutations: four had mutations in the DNA-binding domain, two in the nuclear localisation domain and one in the tetramerisation domain. Clinically, cases with cytoplasmic p53 expression had a poor prognosis similar to that in cases with p53 overexpression or complete absence. CONCLUSIONS: Cytoplasmic p53 expression in patients with pulmonary NEC suggests a high TP53 mutation rate, which is associated with a poor prognosis similar to that in patients with p53 overexpression or complete absence. This cytoplasmic expression should not be misidentified as a wild-type expression. This is the first report, to our knowledge, that demonstrates the implication of cytoplasmic p53 expression in pulmonary NEC.

Malignant Transformation and Leptomeningeal Melanomatosis in a Primary Meningeal Melanocytoma: A Case Report and Review of Literature.

Meningeal melanocytomas of the central nervous system, although typically benign, rarely undergo malignant transformations. A 46-year-old man presented with headache and nausea 4 years after gross total resection of a craniovertebral junction meningeal melanocytoma at another hospital. The initial clinical course was previously reported.1) Computed tomography revealed the presence of multiple intracranial mass lesions. Furthermore, magnetic resonance imaging showed multiple intracranial lesions and meningeal dissemination. A biopsy was performed for a circumflex lesion located in the right frontal lobe. Pathological examination showed anaplastic changes and a Ki-67 index of 33%. Based on the pleomorphic changes and high mitotic activity, the patient was diagnosed with primary cerebral malignant melanoma. The patient received four cycles of nivolumab (80 mg) and ipilimumab (165 mg), followed by whole-brain radiotherapy (37.5 Gy). However, the disease progressed after the third cycle. Genome analysis revealed GNAQ Q209P and SF3B1 R625C mutations, but no treatments related to these gene mutations were available. Despite the seven cycles of nivolumab therapy, the patient eventually passed away 9 months after surgery. This case was a rare example of malignant transformation and leptomeningeal melanomatosis in a meningeal melanocytoma. It highlights the importance of careful follow up after gross total resection. Identification of molecular alterations can lead to better detection of melanocytic melanomas with poor prognosis and high risk of recurrence and metastasis. It can also facilitate the development of novel therapeutic options for these patients.

Overexpression of MicroRNA-138 Affects the Proliferation and Invasion of Urothelial Carcinoma Cells by Suppressing SOX9 Expression.

SRY-box transcription factor 9 (SOX9) is important for sexual differentiation, chondrogenic differentiation, and cell proliferation in cancer. It acts as a target molecule of microRNA (miR)-138 in various tumors and is associated with tumor development and growth. In this study, we analyzed the functions of miR-138 and SOX9 in urothelial carcinoma. SOX9 was highly expressed in invasive urothelial carcinoma tissues. miR-138 precursor transfection of T24 and UMUC2 cells significantly decreased SOX9 expression, indicating that SOX9 is a miR-138 target in urothelial carcinoma. Moreover, miR-138 precursor or SOX9 small interfering RNA (siRNA) transfection decreased the proliferation of urothelial carcinoma cell lines. To further confirm that miR-138-SOX9 signaling is involved in cell proliferation and invasion, urothelial carcinoma cells were transfected with the miR-138 precursor or SOX9 siRNA. This transfection reduced the proliferation and invasion of cells via the promotion of autophagy and apoptosis and G0/G1 cell cycle arrest. These results suggest that miR-138-SOX9 signaling modulates the growth and invasive potential of urothelial carcinoma cells.

A Disintegrin and Metalloproteinase with Thrombospondin Motifs 4 Regulates Pulmonary Vascular Hyperpermeability through Destruction of Glycocalyx in Acute Respiratory Distress Syndrome.

Acute respiratory distress syndrome (ARDS) has no specific and effective treatment, and there is an urgent need to understand its pathogenesis. Therefore, based on the hypothesis that molecules whose expression is upregulated in injured pulmonary vascular endothelial cells (VECs) are involved in the pathogenesis of ARDS, we conducted a study to elucidate the molecular mechanisms and identify target factors for treatment. Primary human lung microvascular endothelial cells (HMVEC-Ls) were stimulated with lipopolysaccharide (LPS) or poly (I:C) and analyzed via a microarray to identify target genes for ARDS. We found that a disintegrin and metalloproteinase with thrombospondin motifs 4 (ADAMTS4) was induced in murine lung VECs in an LPS-mediated ARDS model. Elevated ADAMTS4 was also observed by the immunostaining of lung samples from ARDS patients. The suppression of ADAMTS4 by siRNA in VECs ameliorated LPS-stimulated vascular permeability. The impairment of the cell surface expression of syndecan-1, a marker of the glycocalyx that is an extracellular matrix involved in vascular permeability, was dramatically inhibited by ADAMTS4 suppression. In addition, the suppression of ADAMTS4 protected against LPS-induced reductions in syndecan-1 and the adherens junction protein vascular endothelial cadherin. These results suggest that ADAMTS4 regulates VEC permeability in ARDS and may be a predictive marker and therapeutic target for ARDS.

Enhancing tumour content and tumour cell count using microdissection contributes to higher detection rate of genetic mutations by next-generation sequencers.

Background: Next-generation sequencing (NGS) analysis is becoming indispensable for the treatment of advanced lung cancer. NGS analysis requires a large number of cancer cell-containing tissues; however, it is often difficult for small biopsies to obtain the required quantities. In microdissection, only the tumour parts of a tissue specimen are obtained, which thereby increases the tumour content and tumour cell count of the tissue specimen. In this study, we investigated the extent to which the detection rate of genetic mutations changes by increasing the tumour content using microdissection. Patients and methods: This is a retrospective study. In the genetic panel test using the Oncomine Dx Target Test (ODxTT), participants were divided into two groups: before (group A; April 2021-March 2022) and after (group B; April 2022-December 2022) the introduction of microdissection. The submission criteria for ODxTT were tumour content and tumour cell count >30 % and >2000 in group A, and >40 % and >5000 in group B, respectively. We compared the rate of genetic mutations detected using ODxTT between the two groups. Results: This study included 214 consecutive ODxTT cases between April 2021 and December 2022. In group A (n = 112), 65 cases were adenocarcinoma, 84 involved lung tissue, and 64 underwent bronchoscopic sampling, whereas in group B (n = 102), 55 cases were adenocarcinoma, 91 cases involved lung tissue, and 79 cases underwent bronchoscopic sampling. Furthermore, genetic mutations were detected in 39 of 112 cases (35 %) in group A and 59 of 102 cases (58 %) in group B, which was statistically higher in group B (P = 0.0006). Genetic mutations were detected in 45 of 55 adenocarcinoma cases in group B. The genetic mutations detected in epidermal growth factor rescepor (EGFR), Kirsten rat sarcoma viral oncogene homolog (KRAS), and mesenchymal epithelial transition (MET) were higher in group B. Conclusion: Increasing the number of tumour cells and tumour content can enhance the detection rate of genetic mutations using ODxTT.

The First Case in Japan of Fulminant Myocarditis Due to Multisystem Inflammatory Syndrome in Children (MIS-C) That Required Mechanical Circulatory Support.

Multisystem inflammatory syndrome in children (MIS-C) is a novel hyperinflammatory syndrome that is associated with severe acute respiratory syndrome coronavirus 2 infections. Reports describing the mechanical circulatory support (MCS) and myocardial biopsy for fulminant myocarditis due to MIS-C are limited.A 13-year-old male patient with MIS-C underwent treatment, including immunosuppressive therapy and MCS devices, and managed to recover from pulseless electrical activity cardiac arrest.This is the first patient in Japan with MIS-C who required MCS devices in Japan. Appropriate and immediate treatment with immunosuppressive therapy and MCS devices is important.

THE CRITICAL ROLE OF THE HISTONE MODIFICATION ENZYME SETDB2 IN THE PATHOGENESIS OF ACUTE RESPIRATORY DISTRESS SYNDROME.

ABSTRACT: Introduction: Acute respiratory distress syndrome (ARDS) is a severe hypoxemic respiratory failure with a high in-hospital mortality. However, the molecular mechanisms underlying ARDS remain unclear. Recent findings have indicated that the onset of severe inflammatory diseases, such as sepsis, is regulated by epigenetic changes. We investigated the role of epigenetic changes in ARDS pathogenesis using mouse models and human samples. Methods: Acute respiratory distress syndrome was induced in a mouse model (C57BL/6 mice, myeloid cell or vascular endothelial cell [VEC]-specific SET domain bifurcated 2 [Setdb2]-deficient mice [Setdb2 ff Lyz2 Cre+ or Setdb2 ff Tie2 Cre+ ], and Cre - littermates) by intratracheal administration of lipopolysaccharide (LPS). Analyses were performed at 6 and 72 h after LPS administration. Sera and lung autopsy specimens from ARDS patients were examined. Results: In the murine ARDS model, we observed high expression of the histone modification enzyme SET domain bifurcated 2 ( Setdb2 ) in the lungs. In situ hybridization examination of the lungs revealed Setdb2 expression in macrophages and VECs. The histological score and albumin level of bronchoalveolar lavage fluid were significantly increased in Setdb2 ff Tie2 Cre+ mice following LPS administration compared with Setdb2 ff Tie2 Cre- mice, whereas there was no significant difference between the control and Setdb2 ff Lyz2 Cre+ mice. Apoptosis of VECs was enhanced in Setdb2 ff Tie2 Cre+ mice. Among the 84 apoptosis-related genes, the expression of TNF receptor superfamily member 10b ( Tnfrsf10b ) was significantly higher in Setdb2 ff Tie2 Cre+ mice than in control mice. Acute respiratory distress syndrome patients' serum showed higher SETDB2 levels than those of healthy volunteers. SETDB2 levels were negatively correlated with the partial pressure of oxygen in arterial blood/fraction of inspiratory oxygen concentration ratio. Conclusion: Acute respiratory distress syndrome elevates Setdb2 , apoptosis of VECs, and vascular permeability. Elevation of histone methyltransferase Setdb2 suggests the possibility to histone change and epigenetic modification. Thus, Setdb2 may be a novel therapeutic target for controlling the pathogenesis of ARDS.

Possible False Results With cobas® EGFR Mutation Test v2 and Oncomine Dx Target Test for EGFR Mutation.

BACKGROUND/AIM: Disparities in the results of next-generation sequencing-based multiplex gene panel tests and those of single-gene tests when detecting epidermal growth factor receptor (EGFR) mutations in non-small-cell lung cancer (NSCLC) have been reported. However, the possible underlying causes have not been investigated. The aim of this study was to explore the possibilities and causes of false results obtained using cobas® EGFR Mutation Test v2 (cobas® EGFR) and Oncomine Dx Target Test (ODxTT). PATIENTS AND METHODS: The data of patients with NSCLC who underwent gene assessment using both cobas® EGFR and ODxTT between April 2021 and May 2022 were retrospectively reviewed. Disparate results of EGFR mutation analyses were then reviewed. RESULTS: One hundred and sixteen patients were included in the analysis. The results of six samples were inconsistent. In four samples, exon 20 insertion mutations were detected using cobas® EGFR, but not identified using ODxTT. A fragment analysis was performed on three of the four samples, and all showed negative results for exon 20 insertion. Furthermore, one false negative result was obtained in the ODxTT for both exon 19 deletion and L858R mutations. For exon 19 deletion mutation, a single nucleotide variant from adenine to thymine was identified close to the mutation site. CONCLUSION: False positives for exon 20 insertion may occur when using cobas® EGFR, and false negatives for exon 19 deletion and L858R mutations may occur when using ODxTT.

PDGFRB and NOTCH3 Mutations are Detectable in a Wider Range of Pericytic Tumors, Including Myopericytomas, Angioleiomyomas, Glomus Tumors, and Their Combined Tumors.

Pericytic tumors are subclassified as myopericytomas, myofibromas, angioleiomyomas, and glomus tumors according to the current World Health Organization classification. These pericytic tumors form a continuous morphologic spectrum, including those with combined morphology. However, to our knowledge, no widely accepted criteria for classifying tumors with combined morphology are available. Recent studies have identified platelet-derived growth factor receptor-beta (PDGFRB) gene mutations in a subset of myofibromas, myopericytomas, and myopericytomatoses but not in angioleiomyomas. NOTCH receptor 3 (NOTCH3) mutations have been reported in a subset of infantile myofibromatosis. To assess their potential role in classifying pericytic tumors, we investigated PDGFRB and NOTCH3 mutations in 41 pericytic tumors of variable morphology, including some combined forms. Our results show these mutations to be present in a variety of pericytic tumors, such as myopericytomas (PDGFRB, 3/11; NOTCH3, 4/11), myopericytomatoses (1/2; 1/2), myofibromas (3/6; 0/6), angioleiomyomas (2/13; 3/13), and glomus tumors (5/9; 1/9). Point mutations were identified in 3 tumors in PDGFRB exon 12 (Y562C, S574F, and G576S), 12 tumors in PDGFRB exon 14 (M655I, H657L, and N666K), and 9 tumors in NOTCH3 exon 25 (A1480S/T, D1481N, G1482S, T1490A, E1491K, G1494S, and V1512A). All PDGFRB mutations and NOTCH3 G1482S, T1490A, and G1494S mutations were classified as "deleterious/damaging" by ≥4 of 6 pathogenicity prediction tools in silico. Five-mutation-positive tumors, including 1 myopericytoma-angioleiomyoma, 2 myopericytomatoses-myofibroma, 1 myofibroma-myopericytoma and 1 angioleiomyoma-myopericytoma, were of combined morphology. Therefore, we found PDGFRB and NOTCH3 mutations to be detectable in a much wider variety of pericytic tumors than previously reported and confirmed myopericytomas, myofibromas, angioleiomyomas, and glomus tumors as members harboring PDGFRB or NOTCH3 mutations. Our results thus suggest that PDGFRB or NOTCH3 mutations are not useful for subclassifying members of the pericytic tumor family.

An extremely rare case of interdigitating dendritic cell sarcoma of the parotid gland with a 40­month disease­free survival time after only surgery: A case report.

Interdigitating dendritic cell sarcoma (IDCS) is an extremely rare neoplasm arising from dendritic cells and is mainly located in the lymph nodes. To the best of our knowledge, no treatment strategy has yet been established for IDCS, despite its aggressive clinical features. The present study presents the case of a patient with IDCS who experienced a 40-month disease-free survival time after surgery alone. The patient, a 29-year-old woman, presented with a painful right subaural swelling. Diagnostic MRI and 18F-fludeoxyglucose positron emission tomography/computed tomography revealed a right parotid gland tumour and ipsilateral cervical lymph node. The patient underwent surgical resection, and histological examination of the resected tissue specimens confirmed IDCS diagnosis. To the best of our knowledge, this is only the fifth report of an IDCS located in the parotid gland, with the longest follow-up period among cases of IDCS reported in this region. The positive outcome of this patient suggests that surgical resection may be an effective treatment option for local IDCS. Nonetheless, further studies are required to establish a definitive diagnosis and treatment strategy for IDCS.

Primary pulmonary diffuse large B-cell lymphoma presenting multiple nodules mimicking metastasis: A case report.

Primary pulmonary diffuse large B-cell lymphoma is a rare entity. We describe a case of pulmonary lymphoma with multiple nodules mimicking metastases in a treated patient with rheumatoid arthritis. A 73-year-old man was diagnosed with rheumatoid arthritis at the age of 30. He was treated with leflunomide. He was followed up for a nontuberculous mycobacterial infection. He underwent percutaneous coronary intervention for acute myocardial infarction at the age of 70. In April 2022, routine follow-up revealed new-onset multiple nodules on chest computed tomography (CT). A position emission tomography/CT scan with 18F-fluorodeoxyglucose showed a low-high maximum standardized uptake value by multiple nodules. Pathologic examination of a video-assisted thoracic surgical biopsy revealed pulmonary diffuse large B-cell lymphoma. Systemic chemotherapy with rituximab, cyclophosphamide, vincristine, and prednisolone reduced and eliminated multiple nodules. Pulmonary lymphoma should be considered as a differential diagnosis in the case of multiple nodules on a chest CT.

Preference of grade and lymphovascular invasion over invasive size measurement in stage I lung adenocarcinoma.

AIMS: Although it is necessary to measure the invasive size of lung adenocarcinoma with a lepidic component, it is not uncommon to have trouble in measuring the invasive size of lung adenocarcinoma. This study examined whether there were other stronger prognostic factors than invasive size. METHODS: We characterised the clinicopathological features associated with recurrence-free survival (RFS) of 686 patients with the pathological stage (p-Stage) I lung adenocarcinoma. Moreover, we compared the area under the curve (AUC) values for recurrence between various combinations of pathological-baseline (age & sex & p-Stage based on invasive size) (B(i)) and several prognostic factors, and various combinations of p-baseline based on total tumour size (B(t)) and several prognostic factors. RESULTS: AUC showed no significant differences between B(i) & new International Association for the Study of Lung Cancer grade (G) or vascular invasion (V), and B(t) & G or V. AUC was the highest in B & G & lymphatic invasion (L) & V. RFS was significantly shorter in patients with G3 OR L(+) OR V(+) than in those with G≤2 AND L(-) AND V(-) in each p-Stage based on invasive size (p-Stage(i)) and p-Stage based on total tumour size (p-Stage(t)) (p<0.05), and there were no significant differences in RFS between each p-Stage(i) and p-Stage(t). CONCLUSIONS: In any invasive size or total tumour size of p-Stage I lung adenocarcinoma, G, L and V are more powerful prognostic factors than the size criteria of p-Stage. Therefore, pathologists should focus on these pathological findings.