Masquerading fungal bowel mass in an adolescent: a clinicopathological challenge.

Abdominal masses clubbed with weight loss in the paediatric age group can raise hairs, especially since malignancy is a differential. We present the case of an early adolescent male who presented with abdominal pain and was found to have a mass mimicking a malignancy. The resected surgical specimen revealed entomophthoromycosis of the jejunum and he made a complete recovery following surgery and adjuvant itraconazole. The diagnosis of a fungal aetiology in these cases requires a high index of suspicion and background knowledge of the risk factors, disease occurrence and mode of presentation. Gastrointestinal entomophthoromycosis has an impressive potential for cure if promptly diagnosed and treated.

A rare presentation of idiopathic small bowel diaphragm disease - A case report.

INTRODUCTION: Diaphragm disease, typically associated with long-term non-steroidal anti-inflammatory drug (NSAID) use, manifests as diaphragm-like small bowel strictures, often resulting in bowel obstruction. CASE DESCRIPTION: A 75-year-old male presented with features of recurrent subacute intestinal obstruction, later diagnosed with multiple small bowel strictures via CT imaging. Surgical intervention, including resection and anastomosis, was performed to alleviate the obstruction. Histopathological examination of the resected specimen confirmed diaphragm disease, challenging its traditional association with NSAID use. DISCUSSION: Diaphragm disease, characterized by mucosal and submucosal diaphragm-like strictures, is typically attributed to NSAID usage. However, this case underscores the possibility of diaphragm disease in the absence of NSAID exposure. Pathological findings supported the presence of diaphragm-like strictures, despite the patient's denial of NSAID use. CONCLUSION: This case emphasizes the importance of considering diaphragm disease as a differential diagnosis in patients with intermittent bowel obstruction, even in the absence of NSAID history.

Inducible nonhuman primate models of retinal degeneration for testing end-stage therapies.

The anatomical differences between the retinas of humans and most animal models pose a challenge for testing novel therapies. Nonhuman primate (NHP) retina is anatomically closest to the human retina. However, there is a lack of relevant NHP models of retinal degeneration (RD) suitable for preclinical studies. To address this unmet need, we generated three distinct inducible cynomolgus macaque models of RD. We developed two genetically targeted strategies using optogenetics and CRISPR-Cas9 to ablate rods and mimic rod-cone dystrophy. In addition, we created an acute model by physical separation of the photoreceptors and retinal pigment epithelium using a polymer patch. Among the three models, the CRISPR-Cas9-based approach was the most advantageous model in view of recapitulating disease-specific features and its ease of implementation. The acute model, however, resulted in the fastest degeneration, making it the most relevant model for testing end-stage vision restoration therapies such as stem cell transplantation.

Preexisting Neutralizing Antibodies against Different Adeno-Associated Virus Serotypes in Humans and Large Animal Models for Gene Therapy.

Gene therapy is a potential cure for several inherited retinal dystrophies, and adeno-associated virus (AAV) has emerged as a vector of choice for therapeutic gene delivery to the retina. However, prior exposure to AAVs can cause a humoral immune response resulting in the presence of antibodies in the serum, which can subsequently interfere with the AAV-mediated gene therapy. The antibodies bind specifically to a serotype but often display broad cross-reactivity. A subset of these antibodies called neutralizing antibodies (NABs) can render the AAV inactive, thereby reducing the efficacy of the therapy. The preexisting NAB levels against different serotypes vary by species, and these variations need to be considered while designing studies. Since large animals often serve as preclinical models to test gene therapies, in this review we compile studies reporting preexisting NABs against commonly used AAV serotypes in humans and large animal models and discuss strategies to deal with NABs.

Adeno-Associated Virus (AAV) - Based Gene Therapies for Retinal Diseases: Where are We?

Owing to their small size and safety profiles, adeno-associated viruses (AAVs) have become the vector of choice for gene therapy applications in the retina. In addition to the naturally occurring AAVs, several engineered variants with enhanced properties are being developed for experimental and therapeutic applications. Nonetheless, there are still some challenges impeding successful application of AAVs for a broader range of retinal gene therapies. The small size of AAV particles ensures efficient tissue transduction but also limits the packaging capacity to a few kilobases. Further, AAV's ability to cross retinal barriers is still an obstacle to pan-retinal transduction of the outer retina with tolerable doses. Lastly, despite overall safety, there have been recent reports of immune responses to AAVs in the eye. Hence, evaluation and prediction of immune responses to AAVs has come to be considered an integral part of future clinical success. This review focuses on the use of AAV in clinical trials for retinal diseases, and discusses developments of variants and novel strategies to overcome immune responses to AAVs.

A relook at gastroenteropancreatic neuroendocrine tumours as per 2019 WHO classification-A tertiary centre experience.

INTRODUCTION: Neuroendocrine neoplasm of GIT (gastrointestinal tract) and pancreas is heterogenous with variable clinical features and disease outcomes. Despite multiple attempts of risk stratification by grading and staging, some have unpredictable clinical courses. Well-differentiated grade 3 neuroendocrine tumour (G3NET) is a recent subcategory introduced in the 2019 WHO classification based on morphology, molecular profile and prognosis distinguishing it from neuroendocrine carcinoma(NEC). This study aimed at describing the spectrum of NENs encountered in a tertiary centre with focus on reclassifying previously reported G3 tumours into G3 NET and NEC and comparing the survival between them. METHODOLOGY: This is an 8-year retrospective study of all gastro-entero-pancreatic neuroendocrine neoplasms reclassified according to the 2019 WHO classification based on morphology and Ki-67 index with analysis of the survival rates between the categories. Minimum follow-up period was 20 months. RESULTS: Eighty-six patients with NENs of gastro-entero-pancreas were included, with median age group of 40-60 years (age range 9 to 79 years) and male:female ratio of 1.7:1. The tumour grade correlated with the TNM staging and most of the syndromic NETs were low grade. Eleven percent of the tumours were reclassified as well-differentiated G3NETs. The survival of G3 NETs was higher than NEC. CONCLUSION: Grading of NEN is vital for therapeutic decisions and for prognostication. Currently, morphology is the key to recognise the well-differentiated G3 NETs, but can be subject to interobserver variability. Molecular surrogates may play a role in accurately identifying these entities, the validity of which is warranted.

Immune Responses to Gene Editing by Viral and Non-Viral Delivery Vectors Used in Retinal Gene Therapy.

Inherited retinal diseases (IRDs) are a leading cause of blindness in industrialized countries, and gene therapy is quickly becoming a viable option to treat this group of diseases. Gene replacement using a viral vector has been successfully applied and advanced to commercial use for a rare group of diseases. This, and the advances in gene editing, are paving the way for the emergence of a new generation of therapies that use CRISPR-Cas9 to edit mutated genes in situ. These CRISPR-based agents can be delivered to the retina as transgenes in a viral vector, unpackaged transgenes or as proteins or messenger RNA using non-viral vectors. Although the eye is considered to be an immune-privileged organ, studies in animals, as well as evidence from clinics, have concluded that ocular gene therapies elicit an immune response that can under certain circumstances result in inflammation. In this review, we evaluate studies that have reported on pre-existing immunity, and discuss both innate and adaptive immune responses with a specific focus on immune responses to gene editing, both with non-viral and viral delivery in the ocular space. Lastly, we discuss approaches to prevent and manage the immune responses to ensure safe and efficient gene editing in the retina.

Stanniocalcin2, but Not Stanniocalcin1, Responds to Hypoxia in a HIF1-Dependent Manner in the Retina.

The quest for neuroprotective factors that can prevent or slow down the progression of retinal degeneration is still ongoing. Acute hypoxic stress has been shown to provide transient protection against subsequent damage in the retina. Stanniocalcins - STC1 and STC2 - are secreted glycoproteins that are hypoxia-regulated and were shown to be cytoprotective in various in vitro studies. Hence, we investigated the expression of stanniocalcins in the normal, degenerating and hypoxic retina. We show that the expression of Stc1 and Stc2 in the retina was detectable as early as postnatal day 10 and persisted during aging. Retinal expression of Stc2, but not Stc1, was induced in mice in an in vivo model of acute hypoxia and a genetic model of chronic hypoxia. Furthermore, we show that HIF1, not HIF2, is responsible for regulating Stc2 in cells with the molecular response to hypoxia activated due to the absence of von Hippel Lindau protein. Surprisingly, Stc2 was not normally expressed in photoreceptors but in the inner retina, as shown by laser capture microdissection and immunofluorescence data. The expression of both Stc1 and Stc2 remained unchanged in the degenerative retina with an almost complete loss of photoreceptors, confirming their expression in the inner retina. However, the absence of either Stc1 or Stc2 had no effect on retinal architecture, as was evident from retinal morphology of the respective knockout mice. Taken together our data provides evidence for the differential regulation of STC1 and STC2 in the retina and the prospect of investigating STC2 as a retinal neuroprotective factor.

Systemic and local immune responses to intraocular AAV vector administration in non-human primates.

Positive clinical outcomes in adeno-associated virus (AAV)-mediated retinal gene therapy have often been attributed to the low immunogenicity of AAVs and immune privilege of the eye. However, several recent studies have shown potential for inflammatory responses. The current understanding of the factors contributing to inflammation, such as the pre-existence of serum antibodies against AAVs and their contribution to increases in antibody levels post-injection, is incomplete. The parameters that regulate the generation of new antibodies in response to the AAV capsid or transgene after intraocular injections are also insufficiently described. This study is a retrospective analysis of the pre-existing serum antibodies in correlation with changes in antibody levels after intraocular injections of AAV in non-human primates (NHPs) of the species Macaca fascicularis. In NHP serums, we analyzed the binding antibody (BAB) levels and a subset of these called neutralizing antibodies (NABs) that impede AAV transduction. We observed significantly higher pre-existing serum BABs against AAV8 compared with other serotypes and a dose-dependent increase in BABs and NABs in the serums collected post-injection, irrespective of the serotype or the mode of injection. Lastly, we were able to demonstrate a correlation between the serum BAB levels with clinical grading of inflammation and levels of transgene expression.

SPS(Kayexalate)/CPS(K-Bind) crystals in the gastrointestinal tract-An experience from a tertiary center.

INTRODUCTION: Kayexalate (Sodium Polystyrene Sulfonate/SPS) and K-bind (Calcium Polystyrene Sulfonate/CPS) are cation exchange resins, commonly used for treatment of hyperkalaemia. SPS/CPS induced injury of the gastrointestinal tract(GIT) is rare, can be potentially life threatening but is under-recognized. This study aims to increase awareness of pathologists and clinicians of this under-reported complication of a drug commonly used to treat hyperkalaemia. MATERIALS: Study population comprised patients with SPS/CPS (Kayexalate or its analogues) crystals identified in gastrointestinal specimens from 2017-2019 at a tertiary care centre. Clinical details, relevant investigations, imaging and endoscopic findings, patient follow up details were obtained from the hospital electronic information system. RESULTS: A total of 10 patients with SPS/ CPS crystals in the GIT were encountered over 2 years. Male to female ratio was 9:1, with mean age 66.5years (range 52-82 years). Eight cases were mucosal biopsies and 2 were resection specimens. Additional pathology (tumours, colonic perforation) was present in 80% of patients. The characteristic morphological appearance of the CPS/SPS crystals on H&E stains were supported by special stains -Periodic acid Schiff(PAS) and Acid fast Bacilli(AFB). In all cases, the treatment history with SPS/CPS for hyperkalaemia was obtained only after the histological examination. Most common etiology of hyperkalaemia encountered was chronic kidney disease(CKD)/ Acute on chronic kidney disease. CONCLUSION: It is important for pathologists to recognise the presence of these crystals especially in small biopsies as early feedback to clinicians can help in appropriate management and avoidance of more serious adverse outcome. To the best of our knowledge, this is the first series of 10 consecutive cases of SPS/CPS crystals encountered in gastrointestinal tract to be reported from India.

Prognostic and predictive significance of microsatellite instability in stage II colorectal carcinoma: An 8-year study from a tertiary center in South India.

BACKGROUND: Microsatellite instability (MSI) accounts for 15-20% of colorectal cancer (CRC) and is considered to have favorable stage-adjusted prognosis compared to Microsatellite stable (MSS) CRCs. Determination of MSI in stage II CRC is important for management decisions regarding adjuvant chemotherapy administration. The aim of this study was to determine the prognostic and predictive significance of MSI in stage 2 CRC in the Indian scenario. MATERIALS AND METHODS: A total of 195 patients who underwent curative surgery for stage II CRC from 2010 to 2017 were included. MSI testing by immunohistochemistry (DNA MisMatch Repair proteins) was performed in all. Various clinicopathological factors and disease-free survival and overall survival were assessed between MSI and MSS groups. The effect of treatment in terms of survival benefits with adjuvant therapy in the MSI group was also assessed. RESULTS: 27.1% of the CRCs' showed MSI. Younger age (<50 years), family history of cancer, synchronous/metachronous malignancies, proximal (right sided) location, poor morphological tumour differentiation, mucin production, and presence of peritumoral (Crohn's-like) lymphocytic response showed statistically significant association with MSI. Majority (56%) of our patients showed combined loss of MLH1 and PMS2. Overall, survival among the MSI patients was significantly higher (76.6 ± 4.149 months) than the MSS patients (65.05 ± 3.555)P= 0.04. MSI patients did not show any differences in survival with or without treatment. CONCLUSION: This study highlights the distinct clinicopathological features of MSI-related CRC and the relevance of MSI testing of stage II CRC for management decisions and prognostication.

Linking YAP to Müller Glia Quiescence Exit in the Degenerative Retina.

Contrasting with fish or amphibian, retinal regeneration from Müller glia is largely limited in mammals. In our quest toward the identification of molecular cues that may boost their stemness potential, we investigated the involvement of the Hippo pathway effector YAP (Yes-associated protein), which is upregulated in Müller cells following retinal injury. Conditional Yap deletion in mouse Müller cells prevents cell-cycle gene upregulation that normally accompanies reactive gliosis upon photoreceptor cell death. We further show that, in Xenopus, a species endowed with efficient regenerative capacity, YAP is required for their injury-dependent proliferative response. In the mouse retina, where Müller cells do not spontaneously proliferate, YAP overactivation is sufficient to induce their reprogramming into highly proliferative cells. Overall, we unravel a pivotal role for YAP in tuning Müller cell proliferative response to injury and highlight a YAP-EGFR (epidermal growth factor receptor) axis by which Müller cells exit their quiescence state, a critical step toward regeneration.

Hif1a inactivation rescues photoreceptor degeneration induced by a chronic hypoxia-like stress.

Reduced choroidal blood flow and tissue changes in the ageing human eye impair oxygen delivery to photoreceptors and the retinal pigment epithelium. As a consequence, mild but chronic hypoxia may develop and disturb cell metabolism, function and ultimately survival, potentially contributing to retinal pathologies such as age-related macular degeneration (AMD). Here, we show that several hypoxia-inducible genes were expressed at higher levels in the aged human retina suggesting increased activity of hypoxia-inducible transcription factors (HIFs) during the physiological ageing process. To model chronically elevated HIF activity and investigate ensuing consequences for photoreceptors, we generated mice lacking von Hippel Lindau (VHL) protein in rods. This activated HIF transcription factors and led to a slowly progressing retinal degeneration in the ageing mouse retina. Importantly, this process depended mainly on HIF1 with only a minor contribution of HIF2. A gene therapy approach using AAV-mediated RNA interference through an anti-Hif1a shRNA significantly mitigated the degeneration suggesting a potential intervention strategy that may be applicable to human patients.

Fine-needle Aspiration Cytology of Abdominal Wall Endometriosis: A Meaningful Adjunct to Diagnosis.

Fine-needle aspiration cytology (FNAC) is a simple, non-invasive diagnostic modality which can be performed with ease on any superficially palpable lesion. Surgical scar endometriosis is a rare entity which presents as an abdominal lump in women of reproductive age. It is often a diagnostic pitfall for clinicians due to its nonspecific symptoms. It displays characteristic morphology, which needs to be identified and recognized by a cytopathologist for accurate diagnosis. FNAC can be used as a key diagnostic tool in cases of abdominal wall mass for appropriate patient management, thereby avoiding unnecessary diagnostic procedures. Here, we report the case of a 35-year-old woman who presented with an abdominal lump where FNAC played a vital role in the patient's management.

Gastric Angiomyolipoma Masquerading as Gastric Malignancy.

Gastric angiomyolipoma (AML) is extremely rare, with only 3 cases reported in English literature, all of which presented with upper gastrointestinal bleed, either in the form of hematemesis or melena. A 42-year-old man presented with upper gastrointestinal bleed, the source of which was found to be a large mass in the stomach, which was shown histologically to be gastric AML. This is the fourth but largest tumor (9 × 6 × 5 cm) to be reported to date.

Clinical and Cytological Spectrum of Granulomatous Mastitis and Utility of FNAC in Picking up Tubercular Mastitis: An Eight-Year Study.

INTRODUCTION: Granulomatous Mastitis (GM) is a rare, benign, inflammatory disease of the breast. It is a well known mimicker of malignancy, clinically and radiologically. Patients are often subjected to number of tests for the right diagnosis. Non-specific Granulomatous Mastitis (NGM) and Tubercular Mastitis (TBM) are chief among the various causes of GM. They are important to be diagnosed early as their treatment varies significantly. Fine Needle Aspiration Cytology (FNAC) is simple, patient friendly and primary investigation modality in cases of lump in breast. AIM: To find out the utility of FNAC in differentiating NGM and TBM. MATERIALS AND METHODS: All cases of granulomatous mastitis diagnosed on cytology over eight years were retrospectively retrieved. The clinical and radiological history was obtained from the patient file. The slides were stained with haematoxylin and eosin stain as well as Leishman stains. Special stains like Periodic Acid Schiff (PAS) and Ziehl Neelsen (ZN) stain were used for fungus and Mycobacteriumtuberculosis respectively. Histopathological correlation of the available cases was done. Clinical presentation and cytological morphology of individual cases was studied in detail. RESULTS: Twenty one cases of GM obtained, of which 16 were NGM and five were TBM. Both diseases were common among young reproductive women who presented with unilateral breast lump of varying duration. Almost 25% of NGM and 60% of TBM has clinical suspicion of malignancy. About 30% had radiological suspicion of malignancy. Nearly 62.5% of NGM patients had painful swelling and none of tubercular mastitis patients had pain. About 31% of NGM patients underwent prior abscess drainage and 40% of TBM patients gave history of tuberculosis. Almost 6.25% of NGM and 60% of TBM had axillary lymphadenopathy. Cytologically epithelioid cells were identified in 100% of patients whereas, granulomas were seen in 62.5% and 80% of NGM and TBM smears respectively. Langhans giant cells were frequent among TBM and foreign body giant cell among NGM. Caseous necrosis was seen in 60% of TBM and absent in NGM smears. CONCLUSION: Though, NGM and TBM is said to have overlapping features, our study highlights few clinical and cytological differences which aid in differentiating the two entities at primary level. FNAC along with special stain must be advocated as the primary tool of diagnosis in cases of GM.

Müller glial cell reactivation in Xenopus models of retinal degeneration.

A striking aspect of tissue regeneration is its uneven distribution among different animal classes, both in terms of modalities and efficiency. The retina does not escape the rule, exhibiting extraordinary self-repair properties in anamniote species but extremely limited ones in mammals. Among cellular sources prone to contribute to retinal regeneration are Müller glial cells, which in teleosts have been known for a decade to re-acquire a stem/progenitor state and regenerate retinal neurons following injury. As their regenerative potential was hitherto unexplored in amphibians, we tackled this issue using two Xenopus retinal injury paradigms we implemented: a mechanical needle poke injury and a transgenic model allowing for conditional photoreceptor cell ablation. These models revealed that Müller cells are indeed able to proliferate and replace lost cells following damage/degeneration in the retina. Interestingly, the extent of cell cycle re-entry appears dependent on the age of the animal, with a refractory period in early tadpole stages. Our findings pave the way for future studies aimed at identifying the molecular cues that either sustain or constrain the recruitment of Müller glia, an issue of utmost importance to set up therapeutic strategies for eye regenerative medicine.

Retinal Degeneration and Regeneration-Lessons From Fishes and Amphibians.

PURPOSE OF REVIEW: Retinal degenerative diseases have immense socio-economic impact. Studying animal models that recapitulate human eye pathologies aids in understanding the pathogenesis of diseases and allows for the discovery of novel therapeutic strategies. Some non-mammalian species are known to have remarkable regenerative abilities and may provide the basis to develop strategies to stimulate self-repair in patients suffering from these retinal diseases. RECENT FINDINGS: Non-mammalian organisms, such as zebrafish and Xenopus, have become attractive model systems to study retinal diseases. Additionally, many fish and amphibian models of retinal cell ablation and cell lineage analysis have been developed to study regeneration. These investigations highlighted several cellular sources for retinal repair in different fish and amphibian species. Moreover, major differences in repair mechanisms have been reported in these animal models. SUMMARY: This review aims to emphasize first on the importance of zebrafish and Xenopus models in studying the pathogenesis of retinal diseases and, second, on the different modes of regeneration processes in these model organisms.

Phosphorylation of the Smo tail is controlled by membrane localisation and is dispensable for clustering.

The Hedgehog (Hh) signalling cascade is highly conserved and involved in development and disease throughout evolution. Nevertheless, in comparison with other pathways, our mechanistic understanding of Hh signal transduction is remarkably incomplete. In the absence of ligand, the Hh receptor Patched (Ptc) represses the key signal transducer Smoothened (Smo) through an unknown mechanism. Hh binding to Ptc alleviates this repression, causing Smo redistribution to the plasma membrane, phosphorylation and opening of the Smo cytoplasmic tail, and Smo oligomerisation. However, the order and interdependence of these events is as yet poorly understood. We have mathematically modelled and simulated Smo activation for two alternative modes of pathway activation, with Ptc primarily affecting either Smo localisation or phosphorylation. Visualising Smo activation through a novel, fluorescence-based reporter allowed us to test these competing models. Here, we show that Smo localisation to the plasma membrane is sufficient for phosphorylation of the cytoplasmic tail in the presence of Ptc. Using fluorescence cross-correlation spectroscopy (FCCS), we also demonstrate that inactivation of Ptc by Hh induces Smo clustering irrespective of Smo phosphorylation. Our observations therefore support a model of Hh signal transduction whereby Smo subcellular localisation and not phosphorylation is the primary target of Ptc function.