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The development of next-generation sequencing (NGS) has enabled the discovery of cancer-specific driver gene alternations, making precision medicine possible. However, accurate genetic testing requires a sufficient amount of tumor cells in the specimen. The evaluation of tumor content ratio (TCR) from hematoxylin and eosin (H&E)-stained images has been found to vary between pathologists, making it an important challenge to obtain an accurate TCR. In this study, three pathologists exhaustively labeled all cells in 41 regions from 41 lung cancer cases as either tumor, non-tumor or indistinguishable, thus establishing a "gold standard" TCR. We then compared the accuracy of the TCR estimated by 13 pathologists based on visual assessment and the TCR calculated by an AI model that we have developed. It is a compact and fast model that follows a fully convolutional neural network architecture and produces cell detection maps which can be efficiently post-processed to obtain tumor and non-tumor cell counts from which TCR is calculated. Its raw cell detection accuracy is 92% while its classification accuracy is 84%. The results show that the error between the gold standard TCR and the AI calculation was significantly smaller than that between the gold standard TCR and the pathologist's visual assessment ( p < 0.05 ). Additionally, the robustness of AI models across institutions is a key issue and we demonstrate that the variation in AI was smaller than that in the average of pathologists when evaluated by institution. These findings suggest that the accuracy of tumor cellularity assessments in clinical workflows is significantly improved by the introduction of robust AI models, leading to more efficient genetic testing and ultimately to better patient outcomes. [ABSTRACT FROM AUTHOR]

Our patient presented with an elastic soft mass of his left index finger. Hematoxylin and eosin staining showed a high cellular density with spindle-shaped cells in a storiform pattern. Immunohistochemical staining was positive for CD68, factor XIIIa and α-smooth muscle actin, and negative for CD34, STAT6, S100 protein, and desmin. [ABSTRACT FROM AUTHOR]

Lymphoepithelioma‐like carcinoma is a poorly differentiated carcinoma with prominent lymphoid infiltration occurring in various organs but is exceedingly rare in the colorectal region. This malignancy is frequently associated with Epstein–Barr virus (EBV). Here we report a case of EBV‐associated lymphoepithelioma‐like carcinoma of the cecum in an 84‐year‐old male who presented with occult blood. In situ hybridization for EBV‐encoded small RNAs (EBER) in an endoscopic submucosal dissection specimen showed that the tumor consisted of EBER‐negative well‐differentiated tubular adenocarcinoma and EBER‐positive lymphoepithelioma‐like carcinoma. Real‐time PCR detected 7.16 copies of the EBV genome per cell in a sample microdissected from the latter component. Genotyping analysis demonstrated EBV genotype 1, and viral protein/transcript expression in the tumor showed EBV latency I. Expression of Ephrin receptor A2, a recently reported receptor for EBV, was demonstrated in the tumor cells by immunohistochemistry. To our knowledge, this is the first report of lymphoepithelioma‐like carcinoma in the colorectal region showing a definite association with EBV infection. [ABSTRACT FROM AUTHOR]

A 5‐year‐old girl presented with headache and vomiting. Head computed tomography and magnetic resonance imaging showed a right frontal lobe tumor with marked calcification. The patient underwent resection surgery with suspicion of anaplastic ependymoma, and the tumor was gross totally removed. Pathological examination revealed areas of dense tumor cells with a high nucleocytoplasmic ratio and myxoid areas consisting of tumor cells with a round‐shaped nucleus and eosinophilic cytoplasm. Perivascular pseudorosette, necrosis, circumscribed growth, and microcalcification were also observed. Immunohistochemistry demonstrated negative staining for glial fibrillary protein and epithelial membrane antigen. Diagnosis of a high‐grade neuroepithelial tumor (HGNET) with BCL6 corepressor (BCOR) alteration was made based on pathological findings and internal tandem duplication in the exon 15 of BCOR. Although calcification on radiological and pathological examination is not typical, it would be essential to recognize that calcification could appear in HGNET‐BCOR. [ABSTRACT FROM AUTHOR]

Dear Editor, Eccrine poroma (EP) is a benign cutaneous neoplasm that arises from an intraepidermal eccrine duct. Based on the histopathological findings, the brown globules represent the nest of the tumour cells containing the pigments, and the pinkish-red areas represent the components of the tumour and vessels. [Extracted from the article]

The present study describes the case of a patient with refractory diabetic cystoid macular edema who underwent vitrectomy with en bloc removal of the cystoid lesion component. The current study also performed histopathological and immunohistochemical analyses of the cystoid lesion component to assess fibrin/fibrinogen and advanced glycation end-products (AGEs) immunoreactivity. A 69-year-old Japanese man presented with visual loss in the left eye due to residual cystoid macular edema (CME) refractory to anti-vascular endothelial growth factor therapy. Best-corrected visual acuity was 1.2 in the right eye (OD) and 0.5 in the left eye (OS). Fundus examination showed dot hemorrhages and hard exudates in the peri-macular region with pan-retinal photocoagulation scars in both eye. Swept-source optical coherence tomography revealed CME with slight hyperreflectivity in the cyst OS. A total of 3 months after the initial visit, pars plana vitrectomy was performed, and the translucent solidified component within the cystoid lesion was isolated. Histopathologically, the excised component was elliptical in shape, measuring 0.7x0.4 mm and exhibited homogeneous eosinophilic material without cellular components. No membranous structure was observed surrounding the component. Immunohistochemistry demonstrated that the tissue was positive for fibrin/fibrinogen and weakly positive for AGEs, but was negative for glial fibrillary acidic protein, type 1 collagen and receptor for AGEs. To the best of our knowledge, the present case report is the first to histopathologically examine the contents of refractory CME, and to immunohistochemically demonstrate that fibrin in diabetic CME may be post-translationally modified by AGEs. These results suggested that fibrin in CME may escape degradation by plasmin due to post-translational modifications. [ABSTRACT FROM AUTHOR]

Intraocular lymphoma is a rare neoplasm that occurs only in the eyes and/or central nervous system. Diagnosis of intraocular lymphoma is difficult because its clinical manifestations mimic chronic uveitis. Pathological examination of the vitreous is one of the main diagnostic tools for intraocular lymphoma, but this is challenging due to the sparse cellularity and specimen degeneration. Here, we reviewed 33 cell block preparations from vitreous perfusion fluid in order to examine the significance of cytopathological findings for differential diagnosis using vitreous samples. The cases comprised 12 intraocular lymphomas and 21 non-lymphomatous diseases. Cytologically, vitreous samples from non-lymphoma cases showed lower cellularity than the lymphoma cases. Whereas vitreous material from cases with infectious endophthalmitis showed prominent neutrophilic infiltration, material from sarcoidosis cases showed infiltration of small lymphoid cells, especially CD4-positive T cells. On the other hand, lymphoma cases showed higher cellularity, with large, irregular and atypical lymphoid cells, frequent necrotic cells in the background, and less pronounced neutrophil infiltration. Immunocytochemically, 11 of the 12 lymphoma cases were of the B-cell phenotype and the remaining case was of the T/NK-cell phenotype. In conclusion, careful cytopathological examination or immunocytochemistry of vitreous material facilitates appropriate diagnosis of intraocular lymphoma. [ABSTRACT FROM AUTHOR]

Pleuropulmonary blastoma (PPB) is a rare malignant mesenchymal tumor. It is classified into 3 subgroups, and PPB type 1 is known to be a cystic lesion with good prognosis. Here, we report a case of PPB type 1 seen in a 1-year-old girl whose pulmonary cystic lesion had been followed-up as a congenital pulmonary airway malformation since neonate. The cyst had been diagnosed as congenital pulmonary airway malformation before surgery but the final diagnosis was type 1 PPB. The tumor had a somatic mutation in exon 25 of the DICER 1 gene whereas no germline mutation was found. [ABSTRACT FROM AUTHOR]

Lipoblastoma can arise almost anywhere within the soft tissues, especially in the extremities. It is rarely seen retroperitoneally. A 3-year-old girl presented with a palpable abdominal mass underwent an exploratory laparotomy with resection of the retroperitoneal mass. Based on histopathologic and cytogenetic features, a final diagnosis of lipoblastoma was rendered. At 18-month follow-up, she had no evidence of recurrence. [ABSTRACT FROM AUTHOR]

Key Clinical Message Causes of intrauterine fetal death ( IUFD) are uncertain in most placental mesenchymal dysplasia ( PMD) cases. Our case showed high α-fetoprotein levels in the maternal circulation, markedly dilated subchorionic vessels, and neonatal hemoglobin concentration of 8.4 g/ dL, suggesting that fetal anemia may explain some adverse outcomes in PMD pregnancies. [ABSTRACT FROM AUTHOR]

Most metastatic lung tumors display well-defined, round, multiple nodular shadows, whereas the presence of diffuse ground-glass opacities on chest computed tomography generally suggests non-malignant conditions. Here, we report an unusual case of pulmonary metastasis from gastric cancer in which diffuse ground-glass opacities were observed in all lung segments. A 59-year-old man with a 3-month history of worsening chest pain and shortness of breath was referred to the pulmonary clinic. Chest computed tomography revealed low attenuation areas, suggesting emphysema, along with diffuse ground-glass opacities and interlobular septal thickening in both lungs. A transbronchial lung biopsy specimen revealed signet-ring cell carcinoma infiltrating the alveolar septa. Immunohistochemical staining of the cancer cells was positive for CDX-2, cytokeratin 7, and cytokeratin 20, and negative for surfactant apoprotein-A, TTF-1, and Napsin A. Gastrointestinal endoscopy revealed an ulcerative tumor in the stomach, and a biopsy from the tumor demonstrated malignant cells with similar morphology and immunophenotypes as those in the lungs. The final diagnosis was diffuse lung metastasis from gastric cancer. Our case shows that although multiple, well-defined nodules are typically considered to be the classic presentation of pulmonary metastasis, clinicians should also be aware of the possibility of pulmonary metastasis presenting as diffuse ground-glass opacities. [ABSTRACT FROM AUTHOR]