VISTA: Virtual ImmunoSTAining for pancreatic disease quantification in murine cohorts

Mechanistic studies of pancreatic disease progression using animal models require objective and quantifiable assessment of tissue changes among animal cohorts. Disease state quantification, however, relies heavily on tissue immunostaining, which can be expensive, labor- and time-intensive, and all too often produces uneven staining that is prone to variable interpretation between experts and inaccurate quantification. Here we develop a fully automated semantic segmentation tool using deep learning for the rapid and objective quantification of histologic features using hematoxylin and eosin (H&E) stained pancreatic tissue sections acquired from murine pancreatic cancer models. The tool was successfully trained to segment and quantify multiple histopathologic features of pancreatic pre-cancer evolution, including normal acinar structures, the ductal phenotype of acinar-to ductal metaplasia (ADM), dysplasia, and the expanding stromal compartment. Disease quantifications produced by our computational tool were highly correlated to the results obtained by immunostaining markers of normal and diseased tissue (DAPI, amylase, and cytokeratins; correlation score= 0.9, 0.95, and 0.91, respectively) and were able to accurately reproduce immunostain patterns. Moreover, our tool was able to distinguish ADM from dysplasia, which are not reliably distinguished by immunostaining, and avoid the pitfalls of uneven or poor-quality staining. Using this tool, we quantified the changes in histologic feature abundance for murine cohorts with oncogenic Kras-driven disease at 2 months and 5 months of age (n=12, n=13). The calculated changes in histologic feature abundance were consistent with biological expectations, showing an expansion of the stromal compartment, a reduction of normal acinar tissue, and an increase in both ADM and dysplasia as disease progresses (p= 2e-6, 6e-7, 4e-4, and 3e-5, respectively). These results demonstrate the tool’s efficacy for accurate and rapid quantification of multiple histologic features using an objective and automated platform. Our tool promises to rapidly accelerate and improve the quantification of altered pancreatic disease progression in animal studies.

Gasdermine E-Dependent Mitochondrial Pyroptotic Pathway in Dermatomyositis: A Possible Mechanism of Perifascicular Atrophy

Different mechanisms have been proposed to explain the pathological basis of perifascicular atrophy (PFA), a pathognomonic histologic feature of dermatomyositis (DM); however, the detailed mechanisms remain to be elucidated. There is mitochondrial dysfunction in PFA and expression of mitochondrial apoptosis molecules has been reported in DM. Overexpression of gasdermin E (GSDME) can turn mitochondrial apoptosis to mitochondrial pyroptosis, a newly characterized form of programmed cell death. We determined the expression of proteins involved in the caspase-3- and GSDME-dependent mitochondrial pyroptotic pathway, including BAX, BAK, cytochrome C, caspase-9, caspase-3, GSDME, and IL-1α, in biopsied muscles from DM and control patients. Immunohistochemical analysis showed that those markers were expressed in most fibers in PFA in DM. GSDME-positive and IL-1α-positive staining was mainly localized around punched-out vacuoles or sarcolemma. These markers were significantly upregulated at the protein and mRNA levels in DM versus controls. Our results suggest that caspase-3- and GSDME-dependent mitochondrial pyroptosis are involved in the pathogenetic mechanisms of PFA in DM and that targeting GSDME-dependent mitochondrial pyroptosis may be an effective therapeutic approach for this condition.

Canine Ependymoma: Diagnostic Criteria and Common Pitfalls

Reports of canine ependymoma are generally restricted to single case reports with tumor incidence estimated at 2% to 3% of primary central nervous system (CNS) tumors. While most commonly reported in the lateral ventricle, tumors can occur anywhere in the ventricular system and in extraventricular locations. Rosettes and pseudorosettes are a common histologic feature; however, these features can be mimicked by other CNS neoplasms. Thirty-seven potential ependymoma cases were identified in a retrospective database search of 8 institutions, and a histologic review of all cases was conducted. Of 37 cases, 22 candidate cases were further subjected to a consensus histologic and immunohistochemical review, and only 5 of 37 (13.5%) were conclusively identified as ependymoma. The neuroanatomic locations were the lateral ventricle (3/5), third ventricle (1/5), and mesencephalic aqueduct (1/5). Subtypes were papillary (4/5) and tanycytic (1/5). Histologic features included rosettes (5/5), pseudorosettes (5/5), ependymal canals (2/5), tanycytic differentiation (1/5), blepharoplasts (1/5), ciliated cells (1/5), and high nuclear to cytoplasmic ratio (5/5). Immunolabeling for GFAP (4/4) and CKAE1/3 (3/4) was found in pseudorosettes, rosettes, and scattered individual neoplastic cells. Diffuse but variably intense cytoplasmic S100 immunolabeling was detected in 3 of 4 cases. Olig2 intranuclear immunolabeling was observed in less than 1% of the neoplastic cells (3/3). Tumors that had pseudorosettes and mimicked ependymoma included oligodendroglioma, choroid plexus tumor, pituitary corticotroph adenoma, papillary meningioma, and suprasellar germ cell tumor. These findings indicate that canine ependymoma is an extremely rare neoplasm with histomorphologic features that overlap with other primary CNS neoplasms.

Cystic Crypt Changes in Midgestational Human Vermiform Appendix: An Unrecognized Transient Histologic Feature

Introduction Lewis and Huff briefly described the presence of “microcystic cryptitis” in some of fetal vermiform appendices (VA) at autopsy. We further characterized these crypt changes (CC), their timing of occurrence, and tested their association with infection/inflammatory conditions. Methods Hematoxylin and eosin-stained slides of 345 VA were evaluated for the presence or absence of CC and their different morphologies. Autopsy reports were reviewed for evidence of amniotic fluid or fetal systemic infection and placental inflammatory conditions. Results Crypt dilatation with or without irregularity of the lumen, crypt dilatation with semiattenuated epithelium, intraluminal apoptotic debris and inflammatory cells, especially eosinophils, and foci of swirled spindled cells with calcifications or multinucleated giant cells were observed, either alone or in combination, in at least 58.5% (202/345) of the VA. CC began to appear at 17 weeks, peaked at 20 to 25 weeks (with up to 82% of VA exhibiting CC during this time), and followed by a steady decline beyond 28 weeks gestation. χ2 test of independence showed no significant association ( P = .435; >0.05) between the presence and absence of CC and infection status of the fetus or placenta. Conclusion The underrecognized CC of the developing fetal vermiform appendix (VA) showed distinct temporal pattern of occurrence and did not seem to be affected by the presence or absence of infection, which so far favored their being a part of the normal gut developmental process.

Zonal cortical scarring and tubular thyroidization in kidney biopsies of patients with SLE—histologic indicator for antiphospholipid antibodies

Antiphospholipid antibody syndrome (APS) is an acquired prothrombotic autoimmune disease caused by the presence of antibodies against anionic phospholipids or plasma proteins bound to phospholipids on cell membranes. It can be a primary disease or secondary to other autoimmune diseases, most commonly systemic lupus erythematosus (SLE). Laboratory testing for antiphospholipid antibodies (aPL) may be only transiently positive, so APS could be missed until a catastrophic thrombotic episode or pregnancy morbidity occurs. In the kidneys, this manifests as thrombotic microangiopathy (TMA), and patients present with hypertensive urgency and acute kidney injury. However, APS may not always have a catastrophic presentation but instead a more smoldering course. Kidney biopsy may not show obvious active TMA lesions but rather only chronic injury in the form of zonal cortical scarring and tubular thyroidization. Still, it may warrant anticoagulation therapy. So it is important to recognize this pattern of injury in the biopsy. Herein, we retrospectively study the correlation between presence of this histologic feature in kidney biopsies of SLE patients and positive aPL testing results (anticardiolipin antibodies and/or lupus anticoagulant). Kidney biopsies of SLE patients from 2004 to 2015 ( n = 186) were screened for presence or absence of zonal cortical scarring. Their electronic medical records were reviewed for aPL results. Our study showed low sensitivity (33%) but higher positive predictive value (62%), specificity (89%) and negative predictive value (71%). This histologic finding is therefore not a sensitive screening tool, but if present, greatly increases the likelihood of underlying aPL. We want to emphasize that recognition of this histologic feature in the biopsies of SLE patients is important so as not to miss the opportunity to treat with anticoagulation therapy and possibly slow down the chronic renal damage.

Coexistent Congenital Diaphragmatic Hernia with Extrapulmonary Sequestration

Bronchopulmonary foregut malformations are a heterogeneous but interrelated group of abnormalities that may contain more than one histologic feature. It is helpful to be familiar with the presentation and imaging features of bronchopulmonary foregut malformations presenting as a congenital mass or mass-like lesion, as imaging plays a central role in the evaluation of these lesions since, when symptomatic, clinical features are usually nonspecific. With imaging, the presence of other associated lesions can be determined, facilitating appropriate management to prevent the potential complications. We report a case of coexisting extralobar pulmonary sequestration and ipsilateral diaphragmatic hernia in a term neonate.