Carcinoma showing thymus-like elements (CASTLE) with amyloid deposition in the parotid gland.

Carcinoma showing thymus-like elements (CASTLE) is a rare tumor that commonly occurs in the thyroid gland. Extrathyroidal CASTLE is rarer, and only 11 cases of CASTLE of major salivary glands have been reported to date. We report the first case of amyloid deposition in parotid CASTLE. A 63-year-old man presented with a slowly growing mass in the left parotid region. Computed tomography revealed an approximately 28 × 23 mm mass lesion in the left parotid gland, and squamous cell carcinoma was suspected on biopsy. The patient underwent a parotidectomy with neck dissection. Morphologically, the tumor cells were squamoid and formed nests with lymphoid infiltration. Immunohistochemically, the tumor cells exhibited immunoreactivity for CD5, CD117/c-kit and Bcl-2, p40, and CK5 but not for p16. We diagnosed the tumor as parotid CASTLE. Amyloid deposition was also observed in the primary tumor and metastatic lymph node lesions, which were immunoreactive for cytokeratin 5. Tumor cytokeratin-derived amyloid deposition may be one of characteristics of parotid CASTLE.

Validation of the Diagnostic Criteria for IgG4-Related Periaortitis/Periarteritis and Retroperitoneal Fibrosis (IgG4PA/RPF) 2018, and Proposal of a Revised 2023 Version for IgG4-Related Cardiovascular/Retroperitoneal Disease.

BACKGROUND: In 2018, diagnostic criteria were introduced for IgG4-related periaortitis/periarteritis and retroperitoneal fibrosis (PA/RPF). This study assessed the existing criteria and formulated an improved version.Methods and Results: Between August 2022 and January 2023, we retrospectively analyzed 110 Japanese patients diagnosed with IgG4-related disease (IgG4-RD) involving cardiovascular and/or retroperitoneal manifestations, along with 73 non-IgG4-RD patients ("mimickers") identified by experts. Patients were stratified into derivation (n=88) and validation (n=95) groups. Classification as IgG4-RD or non-IgG4-RD was based on the 2018 diagnostic criteria and various revised versions. Sensitivity and specificity were calculated using experts' diagnosis as the gold standard for the diagnosis of true IgG4-RD and mimickers. In the derivation group, the 2018 criteria showed 58.5% sensitivity and 100% specificity. The revised version, incorporating "radiologic findings of pericarditis", "eosinophilic infiltration or lymphoid follicles", and "probable diagnosis of extra-PA/-RPF lesions", improved sensitivity to 69.8% while maintaining 100% specificity. In the validation group, the original and revised criteria had sensitivities of 68.4% and 77.2%, respectively, and specificities of 97.4% and 94.7%, respectively. CONCLUSIONS: Proposed 2023 revised IgG4-related cardiovascular/retroperitoneal disease criteria show significantly enhanced sensitivity while preserving high specificity, achieved through the inclusion of new items in radiologic, pathological, and extra-cardiovascular/retroperitoneal organ categories.

Identification of uromodulin deposition in the stroma of perinephric fibromyxoid nephrogenic adenoma by mass spectrometry.

Nephrogenic adenoma (NA) is an epithelial lesion that usually occurs in the mucosa of the urinary tract. Rare cases of deep infiltrative or perinephric lesions have also been reported. Recently, NA with characteristic fibromyxoid stroma (fibromyxoid NA) has been proposed as a distinct variant. Although shedding of distal renal tubular cells due to urinary tract rupture has been postulated as the cause of NA in general, the mechanism underlying extraurinary presentation of NA and fibromyxoid stromal change in fibromyxoid NA remains unknown. In this study, we performed mass spectrometry (MS) analysis in a case of perinephric fibromyxoid NA of an 82-year-old man who underwent right nephroureterectomy for distal ureteral cancer. The patient had no prior history of urinary tract injury or radiation. Periodic acid-Schiff staining-positive eosinophilic structureless deposits in the stroma of fibromyxoid NA were microdissected and subjected to liquid chromatography/MS. The analysis revealed the presence of a substantial amount of uromodulin (Tamm-Horsfall protein). The presence of urinary content in the stroma of perinephric fibromyxoid NA suggests that urinary tract rupture and engraftment of renal tubular epithelial cells directly cause the lesion.

Dipeptidyl peptidase-4 inhibitor-related renal disease.

BACKGROUND: Dipeptidyl peptidase-4 (DPP-4) inhibitors are widely used to treat type 2 diabetes (T2D). Lowering blood glucose is expected also to reduce the progression of diabetic nephropathy. We experienced a patient with T2D who achieved good glycemic control with a DPP-4 inhibitor but experienced rapid deterioration of renal function. Therefore, we performed a retrospective study of similar patients treated at our hospital. METHODS: Out of 56 patients with biopsy-proven diabetic nephropathy who underwent native kidney biopsy at Toranomon Hospital from January 2018 through December 2022, we selected 22 patients who had been receiving DPP-4 inhibitors for at least 9 months at the time of kidney biopsy. Of these patients, we evaluated 16 diagnosed with class IIa diabetic nephropathy according to Tervaert's pathologic classification. The yearly estimated glomerular filtration rate (eGFR) slope in the 16 patients was arranged from the highest to the lowest slope. Ten patients with a large eGFR slope had thrombotic microangiopathy (TMA)-like lesions characterized by glomerular endothelial cell proliferation and GBM duplication on kidney biopsy (group A), whereas the remaining 6 patients did not have TMA-like lesions (group B). RESULTS: Group A had a median (interquartile range [IQR]) eGFR of 18.2 (16.2, 26.2) and a yearly median (IQR) eGFR slope of -11.2 (-17.6, -9.2) mL/min/1.73 m2 after of DPP-4 administration, whereas group B had a median (IQR) eGFR of 31.5 (21.9, 34.8) mL/min/1.73 m2 and a yearly median (IQR) eGFR slope of -1.6 (-3.1, -0.3). Renal function declined significantly more rapidly in group A than in group B, and proteinuria was higher in group A than in group B (median [IQR], 3.4 [2.6, 4.4] g/day vs 0.8 [0.4, 1.3] g/day, respectively). Five patients in group A progressed to dialysis during follow-up, but none of the patients in group B did. Median (IQR) hemoglobin A1c was 6.2 % (6.0 %, 6.6 %) in group A and 5.8 % (5.7 %, 6.6 %) in group B. CONCLUSION: DPP-4 inhibitors promote vascular endothelial regeneration, but when this effect occurs in the glomerulus, glomerular endothelial cell proliferation leads to TMA-like lesions, which may cause an increase in proteinuria and rapid decline in renal function.

Elucidation of the mechanism of amyloid A and transthyretin formation using mass spectrometry-based absolute quantification.

Amyloidosis is triggered by the truncation of amyloid precursor proteins, causing organ damages. While previous studies found the truncation of amyloid A (AA) and amyloid transthyretin (ATTR) occurs in C- and N-terminal, respectively, the detailed mechanism of the fibril formation remains unclear. Liquid chromatography mass spectrometry is usually applied for a qualitative purpose, and thus quantification of tryptic peptide residue is difficult. We therefore employed a mass spectrometry-based quantification by isotope-labeled cell-free (MS-QBIC) to analyze the truncation processes in amyloid fibrillogenesis of AA and ATTR using the formalin-fixed paraffin-embedded tissues of autopsy cases. In this study, the process of transthyretin from an 'early fibril state' consisting of full-length ATTR to a 'mature ATTR amyloid fibril' with a truncated low-amyloidogenic segment has been mathematically revealed. The amount of full-length ATTR was nine times higher than in mature fibers. Large cohort studies using MS-QBIC may shed light on the clinical significance of amyloid fibrils.

Immunoglobulin G4-related Tubulointerstitial Nephritis with Simultaneous Resolution of Plasma Cell Infiltration and Fibrosis after Steroid Treatment.

We performed 3 kidney biopsies in a 71-year-old man. At the first biopsy, we made the diagnosis of immunoglobulin G4 (IgG4)-related interstitial nephritis characterized by the simultaneous presence of IgG4-positive plasma cells and characteristic fibrosis with a bird's-eye pattern. At the second biopsy, rather than finding fibrosis as a post-inflammatory scar, we noted that steroid treatment had caused the simultaneous disappearance of IgG4-positive plasma cells and fibrosis and had restored the normal tubular structure. The third biopsy showed the recurrence of the disease with inflammatory cells accompanied by fibrosis. These findings suggest that IgG4-positive plasma cells and fibrosis occur simultaneously.

The Myocardial Accumulation of Aggregated Desmin Protein in a Case of Desminopathy with a de novo DES p.R406W Mutation.

Desminopathy is a cardiac and skeletal myopathy caused by disease-causing variants in the desmin (DES) gene and represents a subgroup of myofibrillar myopathies, where cytoplasmic desmin-postive immunoreactivity is the pathological hallmark. We herein report a 28-year-old Japanese man who was initially diagnosed with sporadic hypertrophic cardiomyopathy with atrioventricular block at 9 years old and developed weakness in the soft palate and extremities. The myocardial tissue dissected during implantation of the ventricular-assisted device showed a dilated phase of hypertrophic cardiomyopathy and intracellular accumulation of proteinase K-resistant desmin aggregates. Genetic testing confirmed a de novo mutation of DES, which has already been linked to desminopathy. As the molecular diagnosis of desminopathy is challenging, particularly if patients show predominantly cardiac signs and a routine skeletal muscle biopsy is unavailable, these characteristic pathological findings of endomyocardial proteinase K-resistant desmin aggregates might aid in clinical practice.

Steep increase in the number of transthyretin-positive cardiac biopsy cases in Japan: evidence obtained by the nation-wide pathology consultation for the typing diagnosis of amyloidosis.

BACKGROUND: In 2019, 2020 and 2022, the Japanese Government approved the use of tafamidis and two technetium-scintigraphies for transthyretin amyloid (ATTR) cardiomyopathy, and announced the patient criteria for tafamidis therapy. In 2018, we had started a nation-wide pathology consultation of amyloidosis. OBJECTIVE: To reveal the impact of approval of tafamidis and technetium-scintigraphy on the diagnosis of ATTR cardiomyopathy. METHODS: Ten institutes participated in this study on the pathology consultation of amyloidosis and shared rabbit polyclonal anti-κ116-133, anti-λ118-134, and anti-transthyretin115-124 antibodies. Proteomic analysis was performed when the typing diagnosis by immunohistochemistry was unavailable. RESULTS: Out of 5400 consultation cases received from April 2018 to July 2022, the type of amyloidosis by immunohistochemistry was determined in 4119 of the 4420 Congo-red positive cases. The incidences of AA, ALκ, ALλ, ATTR, Aß2M and others were 3.2, 11.3, 28.3, 54.9, 0.6 and 1.8%, respectively. Out of 2208 cardiac biopsy cases received, 1503 cases were ATTR positive. There were 4.0 and 4.9 times more total cases and ATTR-positive cases, respectively, in the last 12 months as compared to the first 12 months. CONCLUSIONS: The approval of tafamidis and technetium-scintigraphy raised the awareness of ATTR cardiomyopathy, leading to an upsurge in ATTR-positive cardiac biopsy cases.

Computational Pipeline for Glomerular Segmentation and Association of the Quantified Regions with Prognosis of Kidney Function in IgA Nephropathy.

The histopathological findings of the glomeruli from whole slide images (WSIs) of a renal biopsy play an important role in diagnosing and grading kidney disease. This study aimed to develop an automated computational pipeline to detect glomeruli and to segment the histopathological regions inside of the glomerulus in a WSI. In order to assess the significance of this pipeline, we conducted a multivariate regression analysis to determine whether the quantified regions were associated with the prognosis of kidney function in 46 cases of immunoglobulin A nephropathy (IgAN). The developed pipelines showed a mean intersection over union (IoU) of 0.670 and 0.693 for five classes (i.e., background, Bowman's space, glomerular tuft, crescentic, and sclerotic regions) against the WSI of its facility, and 0.678 and 0.609 against the WSI of the external facility. The multivariate analysis revealed that the predicted sclerotic regions, even those that were predicted by the external model, had a significant negative impact on the slope of the estimated glomerular filtration rate after biopsy. This is the first study to demonstrate that the quantified sclerotic regions that are predicted by an automated computational pipeline for the segmentation of the histopathological glomerular components on WSIs impact the prognosis of kidney function in patients with IgAN.

N-terminal peptide fragment constitutes core of amyloid deposition of serum amyloid A: An imaging mass spectrometry study.

Serum amyloid A (SAA) is an acute phase protein, which undergoes structural changes and deposits in the extracellular matrix, causing organ damage. Systemic AA amyloidosis is a relatively common amyloid subtype among the more than 30 amyloid subtypes, but the mechanism of amyloid fibril formation remains unclear. In this study, we investigated the tissue distribution of SAA derived peptides in formalin-fixed paraffin embedded (FFPE) specimens of human myocardium with amyloidosis using matrix-assisted laser desorption/ionization imaging mass spectrometry (MALDI-IMS). In the whole SAA protein, four trypsin-digested peptides in the range of SAA2-67 were visualized and the N-terminal peptide; SAA2-15, was selectively localized in the Congo red-positive region. The C-terminal peptides; SAA47-62, SAA48-62, and SAA63-67 were detected not only in the Congo red-positive region but also in the surrounding negative region. Our results demonstrate that the N-terminal SAA2-15 plays a critical role in the formation of AA amyloid fibril, as previously reported. Roles of the C-terminal peptides require further investigation.

Renal-limited ANCA-associated vasculitis during erlotinib treatment for lung carcinoma.

Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) had clinical success in the treatment of non-small cell lung carcinoma (NSCLC). An effect of this drug on kidney has not been clarified and the occurrence of glomerulonephritis related to EGFR-TKI has rarely been reported. We present the case of a 71-year-old man with NSCLC who developed proteinuria and microscopic hematuria with the rise in a titer of MPO-ANCA, when 2 years and 3 months passed since the initiation of erlotinib, one of oral EGFR-TKI. Two serial biopsies support that ANCA-associated vasculitis may have been modified by the persistent use of erlotinib. We initiated intravenous pulse therapy with methylprednisolone followed by oral prednisone. The proteinuria has decreased and serum CRP was normalized. However, the serum creatinine level and hematuria did not change during the treatment period. While EGFR inhibition is implicated in protective control for glomerulonephritis, it may exacerbate vasculitis. Close monitoring of the kidney function and urinary findings is required during the use of EGFR inhibitors, such as erlotinib, because it may cause renal adverse events.

Autopsy case with concurrent transthyretin and immunoglobulin amyloidosis.

An 85-year-old man with a history of aortic dissection suddenly fainted, underwent cardiac heart arrest, and died. An autopsy was performed, but the cause of death was not grossly identified. Congo red staining detected amyloid deposits in systemic organs, including the heart, lungs, liver, and kidneys. Immunohistochemical (IHC) analysis revealed immunoglobulin (Ig) λ light chain (-λ) in systemic blood vessels and transthyretin (TTR) in the heart and lungs. Ig-λ was predominantly positive in the blood vessels of the lungs, while TTR was detected in the alveolar septum. In the heart, Ig-λ was positive in the endocardium and blood vessels, and TTR was positive in nodular deposits between cardiomyocytes. The concurrent deposition of Ig-λ and TTR in the heart was further substantiated by laser microdissection (LMD)-liquid chromatography-tandem mass spectrometry (LC-MS/MS) at each deposition site. Despite systemic deposition of Ig-λ, bone marrow biopsy findings were not diagnostic for multiple myeloma. In summary, we present an autopsy case of concurrent Ig-λ and TTR deposition as revealed by IHC and LC-MS/MS. When Congo red staining and IHC results are indeterminate due to the deposition of multiple amyloid proteins, LMD-LC-MS/MS is useful for determining the precursor protein.

Predominant mesangial IgM, C3, and λ light chain depositions and interstitial nephritis in a patient with overlap syndrome and positivity for anti-mitochondrial M2 antibody: a case report.

Overlap syndrome refers to a group of conditions that have clinical features of more than one well-characterised rheumatic disease and meet the respective classification criteria. There are no typical renal histological findings in overlap syndrome. When patients with overlap syndrome develop renal dysfunction, various potential causes, including lupus nephritis (LN), renal crisis by systemic sclerosis, interstitial nephritis, and so on, need to be distinguished. Here, we report a 44-year-old woman with overlap syndrome involving systemic lupus erythematosus (SLE), diffuse cutaneous systemic scleroderma, and Sjogren's syndrome, who was also positive for anti-mitochondrial M2 antibody. She developed glomerular haematuria, proteinuria, and increase in creatinine appeared gradually. Suspecting LN, renal biopsy was performed. However, in the interstitium, mild infiltration of lymphocytes and plasma cells and very partial fibrosis were observed. Immunofluorescence microscopy revealed predominant mesangial immunoglobulin M, C3, and λ light chain staining. Overall, LN was not diagnosed based on these findings. Renal dysfunction was normalised by glucocorticoid treatment for 3 months. This case suggests the importance of a renal diagnosis based on renal pathological findings, especially in a case of overlap syndrome including SLE.

An advanced case of gastric histiocytic sarcoma treated with chemotherapy and gastrectomy: a case report and review of literature.

Histiocytic sarcoma is a relatively new disease category and the gastrointestinal origin is sporadic. We report a case of a 74-year-old woman who underwent chemotherapy and proximal gastrectomy for extremely rare, advanced gastric histiocytic sarcoma. The resected specimen was subjected to numerous immunostainings to meet the diagnostic criteria of histiocytic sarcoma and was positive for the histiocyte markers' cluster of differentiation 68 and lysozyme. The markers of Langerhans cells, follicular dendritic cells, and myelocyte were all negative. Six reports of surgical resection of histiocytic sarcoma originating in the stomach exist, including our case. We reviewed the clinical course and the histological and immunohistochemical diagnostic features of surgically resected gastric histiocytic sarcoma.

Glomerular Classification Using Convolutional Neural Networks Based on Defined Annotation Criteria and Concordance Evaluation Among Clinicians.

INTRODUCTION: Diagnosing renal pathologies is important for performing treatments. However, classifying every glomerulus is difficult for clinicians; thus, a support system, such as a computer, is required. This paper describes the automatic classification of glomerular images using a convolutional neural network (CNN). METHOD: To generate appropriate labeled data, annotation criteria including 12 features (e.g., "fibrous crescent") were defined. The concordance among 5 clinicians was evaluated for 100 images using the kappa (κ) coefficient for each feature. Using the annotation criteria, 1 clinician annotated 10,102 images. We trained the CNNs to classify the features with an average κ ≥0.4 and evaluated their performance using the receiver operating characteristic-area under the curve (ROC-AUC). An error analysis was conducted and the gradient-weighted class activation mapping (Grad-CAM) was also applied; it expresses the CNN's focusing point with a heat map when the CNN classifies the glomerular image for a feature. RESULTS: The average κ coefficient of the features ranged from 0.28 to 0.50. The ROC-AUC of the CNNs for test data varied from 0.65 to 0.98. Among the features, "capillary collapse" and "fibrous crescent" had high ROC-AUC values of 0.98 and 0.91, respectively. The error analysis and the Grad-CAM visually showed that the CNN could not distinguish between 2 different features that had similar visual structures or that occurred simultaneously. CONCLUSION: The differences in the texture or frequency of the co-occurrence between the different features affected the CNN performance; thus, to improve the classification accuracy, methods such as segmentation are required.

Poor Myocardial Compaction in a Patient with Recessive MYL2 Myopathy.

Recessive mutations in the Myosin regulatory light chain 2 (MYL2) gene are the cause of an infantile-onset myopathy, associated with fatal myocardial disease of variable macromorphology. We here present the first Japanese family affected with recessive MYL2 myopathy. Affected siblings manifested typical features and the proband's autopsy findings were compatible with the diagnosis of noncompaction cardiomyopathy. The rapidly progressive clinical course of this recessive MYL2 cardiomyopathy highlights the crucial role of c-terminal tails in MYL2 protein in maintaining cardiac morphology and function.

Case of aquagenic urticaria: Case report and the results of histopathological examination.

Aquagenic urticaria (AU) is a rare skin condition in which dermal contact with water serves as a trigger of urticaria and pruritus. To make a diagnosis, a water challenge test is useful. We herein report a 16-year-old Japanese boy diagnosed with AU by water provocation test. The induced skin lesion histologically showed prominent degranulation of mast cells and lymphocytic infiltration throughout the dermis. This is the second report documenting the histopathological features of AU.

Mass spectrometry-based absolute quantification of amyloid proteins in pathology tissue specimens: Merits and limitations.

To clarify the significance of quantitative analyses of amyloid proteins in clinical practice and in research relating to systemic amyloidoses, we applied mass spectrometry-based quantification by isotope-labeled cell-free products (MS-QBIC) to formalin-fixed, paraffin-embedded (FFPE) tissues. The technique was applied to amyloid tissues collected by laser microdissection of Congo red-stained lesions of FFPE specimens. Twelve of 13 amyloid precursor proteins were successfully quantified, including serum amyloid A (SAA), transthyretin (TTR), immunoglobulin kappa light chain (IGK), immunoglobulin lambda light chain (IGL), beta-2-microglobulin (B2M), apolipoprotein (Apo) A1, Apo A4, Apo E, lysozyme, Apo A2, gelsolin, and fibrinogen alpha chain; leukocyte cell-derived chemotaxin-2 was not detected. The quantification of SAA, TTR, IGK, IGL, and B2M confirmed the responsible proteins, even when the immunohistochemical results were not decisive. Considerable amounts of Apo A1, Apo A4, and Apo E were deposited in parallel amounts with the responsible proteins. Quantification of amyloid protein by MS-QBIC is feasible and useful for the classification of and research on systemic amyloidoses.