Lymphoplasmacytic Inflammation Research Articles

Toxicity Profile of eBAT, a Bispecific Ligand-Targeted Toxin Directed to EGFR and uPAR, in Mice and a Clinical Dog Model.

EGFR-targeted therapies are efficacious, but toxicity is common and can be severe. Urokinase type plasminogen activator receptor (uPAR)-targeted drugs are only emerging, so neither their efficacy nor toxicity is fully established. Recombinant eBAT was created by combining cytokines EGF and uPA on the same single-chain molecule with truncated Pseudomonas toxin. Its purpose was to simultaneously target tumors and their vasculature in the tumor microenvironment. In prior studies on mice and dogs, the drug proved efficacious. Here, we report the safety of eBAT in normal wildtype, uPAR knockout, and immunoreplete and immunodeficient tumor-bearing mice, as well as in dogs with spontaneous sarcoma that more closely mirror human cancer onset. In immunocompetent mice, tumor-bearing mice, uPAR knockout mice, and mice receiving species-optimized eBAT, toxicities were mild and self-limiting. Likewise, in dogs with life-threatening sarcoma given dosages found to be biologically active, eBAT was well tolerated. In mice receiving higher doses, eBAT was associated with dose-dependent evidence of liver injury, including portal biliary hyperplasia, oval cell proliferation, lymphoplasmacytic inflammation, periportal hepatocellular microvesicular change, hemorrhage, necrosis, and apoptosis. The results support continuing the clinical development of eBAT as a therapeutic agent for individuals with sarcoma and other cancers.

Assessing IgG4-related ophthalmic disease and its mimics: a comparison of ACR/EULAR, organ-specific and revised comprehensive diagnostic criteria

AimsDiagnosis of IgG4-related ophthalmic disease (IgG4-ROD) rests on the correlation of clinical features, serological testing and histopathology, using internationally accepted diagnostic criteria for objective interpretation; however, several mimickers of IgG4-RD...

From diverticulosis to complicated diverticular disease: Progression of myogenic alterations and oxidative imbalance.

The natural history and pathophysiology of diverticular disease (DD) are still uncertain. An ex-vivo human complicated DD (cDD) model has recently shown a predominant transmural oxidative imbalance. The present study aims to evaluate whether the previously described alterations may precede the symptomatic form of the disease. Colonic surgical samples obtained from patients with asymptomatic diverticulosis (DIV), complicated DD, and controls were systematically and detailed morphologically and molecularly analyzed. Therefore, histologic, histomorphometric, immunohistochemical evaluation, and gene and protein expression analysis were performed to characterize colonic muscle changes and evaluate chronic inflammation, oxidative imbalance, and hypoxia. Functional muscle activity was tested on strips and isolated cells in response to contractile and relaxant agents. Compared with controls, DD showed a marketed increase in muscle layer thickness, smooth muscle cell syncytium disarray, and increased interstitial fibrosis; moreover, the observed features were more evident in the cDD group. These changes mainly affected longitudinal muscle and were associated with altered contraction-relaxation dynamics and fibrogenic switch of smooth muscle cells. Chronic lymphoplasmacytic inflammation was primarily evident in the mucosa and spared the muscle. A transmural increase in carbonylated and nitrated proteins, with loss of antioxidant molecules, characterized both stages of DD, suggesting early oxidative stress probably triggered by recurrent ischemic events, more pronounced in cDD, where HIF-1 was detected in both muscle and mucosa. The different DD clinical scenarios are part of a progressive process, with oxidative imbalance representing a new target in the management of DD.

A Novel Model of Staphylococcus aureus-Induced Lymphoplasmacytic Rhinosinusitis in Rats.

Chronic rhinosinusitis (CRS) is characterized by sinonasal mucosal inflammation. Staphylococcus aureus (S. aureus) is associated with severe CRS phenotypes. Different animal models have been proposed to study the association of CRS and S. aureus. However, current animal models are expensive due to the use of large animals, have high barriers to ethics approval, or require invasive surgical intervention, necessitating a need for a model that can overcome these limitations. This study aimed at establishing a reliable and efficient rat lymphoplasmacytic inflammatory model for rhinosinusitis. Sprague Dawley rats received a daily intranasal application of 20 μL of saline, S. aureus CI-182 exoprotein (250 μg/mL), or exoprotein CI-182 in combination with S. aureus clinical isolate (CI-908 or CI-913) 108 colony-forming unit (CFU)/mL. The rats' sinuses were harvested at 1 and 2 weeks post-intervention. The CFU and histopathologic examination of inflammation were evaluated. S. aureus clinical isolates CI-908 or CI-913 in combination with the exoprotein (CI-182) had higher CFUs and caused persistently higher inflammation at both the 1 and 2-week post-intervention compared to the exoprotein and saline group. The observed inflammatory cell type was lymphoplasmacytic. This study provided evidence that the combination of a S. aureus exoprotein with S. aureus induces inflammation that persists for a minimum of two weeks post-intervention. This model is the first known animal model to create the lymphoplasmacytic inflammation subtype seen in CRS patients. This offers a cost-effective, accessible, non-invasive, and easy-to-replicate model to study the causes and treatment of such inflammation.

Protective Effects of a Red Orange and Lemon Extract (RLE) on the Hepatotoxicity Induced by Ochratoxin A in Rats.

Ochratoxin A (OTA) is a highly potent mycotoxin that contaminates many kinds of food and feed sources. Its significant impact on human health and animal productivity makes it a topic of particular concern. The role of specific bioactive compounds used as dietary antioxidants is believed to be substantial due to their capacity to act as free radical scavengers. Because of the well-known oxidative stress induced by OTA, the primary objective of this work was to evaluate the antioxidant effects of a standardized powder extract recovered from citrus processing waste, red orange and lemon extract (RLE), on liver damage induced by OTA in a rat model. This study aimed to examine the impact of oral administration of RLE (90 mg/kg b.w.) on hepatic function and oxidative balance in Sprague-Dawley rats (n = 6/group) treated with OTA (0.5 mg/kg b.w.) over a period of 14 days. The administration of OTA alone resulted in both biochemical changes and an imbalance in redox status in the liver. However, the use of RLE alleviated the activity of antioxidant enzymes and dramatically decreased the serum levels of ALT (alanine aminotransferase), AST (aspartate aminotransferase), and ALP (alkaline phosphatase), providing evidence of its protective benefits. Based on the findings from liver histology tests, the administration of RLE resulted in mitigation of lymphoplasmacytic inflammation, steatosis, and necrosis in the OTA group. These results indicate that the novel phytoextract RLE holds potential for application in the field of nutraceuticals.

Inflammatory pseudotumor of frontal sinus mimicking an aggressive malignancy: a rare case with diagnostic challenge on fine needle aspiration

Abstract Introduction/Objective Inflammatory pseudotumor (IPT) of sinonasal tract is a rare disease that sometimes mimicks malignancy in radiographic findings. Diagnosis of IPT on fine needle aspiration (FNA) is challenging due to limited cellularity and lack of architectural evaluation. Methods/Case Report Patient is a 59-year-old female presented with left front head swelling, facial pain and pressure. Imaging demonstrated a 3.0 cm hypermetabolic frontal sinus mass with osseous erosion through the calvaria table and deviating the adjacent dura, suspicious for malignancy. Also, an incidental 6.8 cm renal mass was identified and was proven to be clear cell renal cell carcinoma. FNA from frontal sinus showed loosely cohesive atypical cells with prominent nucleoli and occasional mitotic activity mixed with lymphoplasmacytic inflammation and eosinophils. Extensive immunostains showed that the lesional cells were only weakly stained for CD10 and desmin. Because of prominent cytologic atypia and radiological concerning for malignancy, FNA was diagnosed as malignancy not further classified. The patient underwent frontal sinus resection and the surgical specimen showed spindle cell proliferation surrounded by reactive woven bone with plump osteoblasts in a myxocollagenous stroma containing mixed lymphoplasmacytic cells and eosinophils. The spindle cells are positive for actin and calponin, negative for ALK. The spindle cells and plump osteoblasts corresponded to the atypical cells observed on FNA. The overall finding is consistent with IPT, although inflammatory myofibroblastic tumor cannot be completely ruled out. During follow up, the patient developed metastatic renal cell carcinoma in lung. Her frontal sinus lesion was stable for 17 months after surgery. Results (if a Case Study enter NA) NA Conclusion IPT of sinonasal tract is a rare lesion that sometimes demonstrate aggressive radiologic features. FNA from IPT poses a diagnostic challenge and can be misinterpreted as malignancy due to prominent cytologic atypia. Being aware of this rare entity helps avoid misdiagnosis and triggers the request for core biopsy during onsite evaluation.

Severe bronchiectasis resulting from chronic bacterial bronchitis and bronchopneumonia in a jungle cat.

Bronchiectasis is irreversible bronchial dilation that can be congenital or acquired secondary to chronic airway obstruction. Feline bronchiectasis is rare and, to our knowledge, has not been reported previously in a non-domestic felid. An ~10-y-old female jungle cat (Felis chaus) was presented for evaluation of an abdominal mass and suspected pulmonary metastasis. The animal died during exploratory laparotomy and was submitted for postmortem examination. Gross examination revealed consolidation of the left caudal lung lobe and hila of the cranial lung lobes. Elsewhere in the lungs were several pale-yellow pleural foci of endogenous lipid pneumonia. On cut section, there was severe distension of bronchi with abundant white mucoid fluid. The remaining lung lobes were multifocally expanded by marginal emphysema. Histologically, ectatic bronchi, bronchioles, and fewer alveoli contained degenerate neutrophils, fibrin, and mucin (suppurative bronchopneumonia) with rare gram-negative bacteria. Aerobic culture yielded low growth of Proteus mirabilis and Escherichia coli. There was chronic bronchitis, marked by moderate bronchial gland hyperplasia, lymphoplasmacytic inflammation, and lymphoid hyperplasia. The palpated abdominal mass was a uterine endometrial polyp, which was considered an incidental, but novel, finding. Chronic bronchitis and bronchopneumonia should be considered as a cause of bronchiectasis and a differential diagnosis for respiratory disease in non-domestic felids.

Esophageal Stricture and Occlusion in a Green Sea Turtle (Chelonia mydas)

Abstract In December 2022, a juvenile female green sea turtle (Chelonia mydas) was stranded in North Carolina, USA. On admission to rehabilitation, physical exam and point-of-care diagnostics found severe emaciation, a healing wound to the left cranial neck, abnormal buoyancy, a heavy burden of epibiota on its carapace, anemia, and hypoproteinemia. Over time, the turtle exhibited progressive weight loss, dysphagia, and regurgitation characterized by forcefully ejecting water and masticated fish from its nares. When attempted tube feeding was unsuccessful, a cranial esophageal stricture was suspected. Computed tomography and ultrasonography revealed no evidence of an esophageal foreign body or intraluminal and extraluminal masses. Esophagoscopy confirmed a cranial esophageal stricture; however, neither bouginage nor surgical resection via an esophagostomy was successful, and the turtle was euthanized. Necropsy confirmed an esophageal stricture and occlusion, diffuse serous atrophy of fat, and widespread muscle atrophy. Histopathology revealed the esophageal stricture was comprised of focal marked fibrosis with edema and mild perivascular lymphoplasmacytic inflammation. Given the age class and size of the turtle, the authors suspect the esophageal stricture and occlusion were acquired secondary to unknown prior trauma. Esophageal stricture in sea turtles is a possible severe sequela of esophageal injury and likely carries a guarded prognosis for survival and release.

Copper-associated chronic hepatitis in Cavalier King Charles spaniels.

Copper-associated chronic hepatitis (CuCH) is poorly characterised in Cavalier King Charles spaniels (CKCS). Hepatic copper accumulation was qualitatively and quantitatively assessed, and blood samples were used for genetic testing to screen for known CuCH-associated genetic variants. The study included 13 CKCS with CuCH and eight unaffected controls. Increased transaminase activities, elevated biliary enzyme concentrations and portal hypertension were documented in 100%, 73% and 38% of dogs with CuCH, respectively. Five dogs had three or more abnormalities in measures of liver function. All 11 dogs with CuCh that underwent genetic testing were homozygous negative for the COMMD1 deletion and ATP7A variant but homozygous positive (n = 7) or heterozygous (n = 4) for the ATP7B variant. Liver histology often demonstrated marked architectural distortion by severe, bridging fibrosis and regenerative nodules with lymphoplasmacytic inflammation. Centrilobular copper accumulation characterised early cases with minimal fibrosis. When fibrosis was significant, copper was often differentially concentrated within regenerative nodules. Chelation therapy resolved laboratory derangements and portal hypertension in five of seven dogs. Of the 7 non-surviving dogs with CuCH, 6 had not received chelation therapy. Limitations include a small cohort size and the lack of pedigree analyses to corroborate heritability. CuCH should be considered in CKCS with suspected liver disease. Long-term prognosis seems favourable in dogs receiving chelation therapy, notwithstanding the presence of previously reported negative prognostic markers.

Characterization of gastrointestinal inflammatory cell type in equine glandular gastric disease.

To compare small intestinal inflammation with gastric inflammation in horses with and without equine gastric glandular disease (EGGD), we evaluated endoscopic, macroscopic, and microscopic findings of the glandular stomach and microscopic findings of the small intestine. 36 horses. Horses underwent endoscopy and were scored for EGGD. After euthanasia, stomachs were collected and macroscopically evaluated. Normal pyloric mucosa, glandular lesions, and small intestinal (duodenum, mid-jejunum, and ileum) samples were collected and processed for microscopic examination. Cellular infiltrate was scored. Immunohistochemistry (CD3, CD20, and Iba-1) was performed on the ventral pylorus and small intestine of horses with mild to moderate lymphoplasmacytic infiltrate. A Spearman's correlation coefficient was used to evaluate the relationship of EGGD grade with gastric glandular inflammation, and the relationships of cellular infiltrate type and severity among glandular stomach, duodenum, jejunum, and ileum. Gastrointestinal inflammation was common, with gastric inflammatory infiltrate identified in 92%, duodenal inflammatory infiltrate in 83%, jejunal inflammatory infiltrate in 92%, and ileal inflammatory infiltrate in 92% of horses. Endoscopic evidence of gastric disease (hyperemia or EGGD grade ≥ 2/4) was not associated with the presence or severity of duodenal, jejunal, or ileal inflammation. Gastric lymphoplasmacytic inflammation grade ≥ 2 was associated with duodenal lymphoplasmacytic inflammation grade ≥ 2. This was a convenience sample of horses presenting for euthanasia. Medical history (including deworming history) was unknown. Gastric lymphoplasmacytic inflammation is associated with duodenal lymphoplasmacytic inflammation but not more distal small intestinal inflammation. Intestinal inflammation is not associated with endoscopic findings (hyperemia or EGGD grade ≥ 2/4).

THU452 Polyostotic Fibrous Dysplasia Complicated By Aneurysmal Bone Cyst In A Patient With McCune-Albright Syndrome

Abstract Disclosure: E. Milazzo: None. K.L. Hermayer: None. Introduction: McCune-Albright Syndrome (MAS) is a rare mosaic disorder with GNAS mutations, encoding the alpha-subunit of the Gs G-coupled protein receptor, activating it, and inappropriately producing cAMP. The hyperfunctioning endocrinopathies associated with MAS are due to signaling through the TSH, LH, FSH, GHRH, and ACTH receptors. MAS clinical presentation occurs with café-au-lait skin macules, precocious puberty, and fibrous dysplasia (FD) of the bone. FD is a benign tumor that leads to increased rates of bone fractures and if it causes facial deformities, can be complicated with orbital neuropathies. An aneurysmal bone cyst (ABC) is a blood-filled cyst that can be a primary or secondary lesion due to co-existing lesions. ABC is a rare complication of FD. We report a rare case of ABC in a MAS patient who presented with acute visual disturbance and enlargement of the forehead and was successfully treated with surgery. Clinical Case: A 20-year-old female diagnosed with MAS at the age of 2 who had precocious puberty by the 3rd year of life and developed polyostotic FD in the right arm, left femur, cranial, and skull bones with multiple long bone fractures by the age of 5-6 and required numerous orthopedic surgeries. She presented with the characteristic café-au-lait skin macules on the back and right arm. In 2018, a slow decline of left eye vision required left cranial decompression of the optic nerve, with pathology showing fibrous tissue compatible with FD. In 2021, she complained of acute right forehead enlargement, compressing her right eye with blurry vision. An MRI showed FD involving the facial and skull bones with a new expansible lesion in the right frontal bone with internal layering fluid, exerting a mild mass effect on the frontal lobe and extending superiorly to the orbit with inferior displacement of the globe. These findings were consistent with an ABC. Right frontal craniectomy and cranioplasty were performed in 12/2021, with pathology showing a fibrous pseudocyst wall with associated lymphoplasmacytic inflammation and evidence of prior hemorrhage with Ki-67 in the cyst wall at 15%. Lab work showed chronic alkaline phosphatase elevation at 567IU/L (42-106IU/L), normal calcium at 9.2mg/dl (8.4-10.3mg/dl), phosphate at 3.3mg/dl (3.3-5.1mg/dl), and PTH at 26pg/ml (15-65mg/dl), with Vitamin D insufficiency at 25.1ng/ml (30-100ng/ml). Endocrinology workup was negative for thyroid, adrenal, gonadotrophic, and GH dysfunction. 5 months post-surgery, the patient demonstrated complete recovery, and MRI showed no recurrence of the ABC. Conclusion: ABC is a benign solitary tumor generally arising from the metaphysis of long bones and rarely involves the cranium. ABC associated with FD has only been reported in a few cases. The treatment is surgical excision, with radiation and cryotherapy used in nonorbital cases. Presentation: Thursday, June 15, 2023

IgG4 Positivity in Chronic Tonsillitis: A New Component of IgG4-Related Disease?

Immunoglobulin G4-related disease (IgG4-RD) and chronic tonsillitis are both chronic fibroinflammatory diseases in which tissue atrophy is sometimes observed. In this study, the authors aimed to investigate the pathologic IgG4 positivity in tonsillectomy specimens and hypothesized to name it as a new clinical component of IgG4-RD if there is significant IgG4 positivity in chronic tonsillitis. A total of 73 patients who underwent tonsillectomy for chronic tonsillitis were included in this study. Of these, 31 patients had atrophic form chronic tonsillitis. Pathologic examinations and specific IgG4 immunohistochemical staining were performed by the same experienced pathologist in terms of IgG4-RD. Sixty-three percent (n=46) of the cases were male, 37% (n=27) were female, their ages ranged from 3 to 51, and the mean age was 19.11±14.82. It was determined that 23.3% (n=17) of the cases participating in the study were IgG4-positive. When the pathologic grades of the cases were examined; it was observed that 13.7% (n=10) were Grade I, 65.8% (n=48) were Grade II, and 20.5% (n=15) were Grade III. A statistically significant difference was found between the pathology degrees of the cases according to the IgG4 groups ( P =0.001; P <0.01). The authors concluded that as the histopathologic grades of chronic lymphoplasmacytic inflammation in tonsils specimen increase, IgG4 positivity rates also increase. Therefore, this clinical entity may be a new IgG4-related disease state in cases with chronic tonsillitis. Level II.

Non-cutaneous syncytial myoepitheliomas are identical to cutaneous counterparts: a clinicopathologic study of 24 tumors occurring at diverse locations.

Cutaneous syncytial myoepithelioma (CSM) is a rare myoepithelioma variant of skin, characterized by intradermal syncytial growth of spindle cells with a distinct immunophenotype of EMA and S100 positivity and infrequent keratin expression. While CSM was first described as a cutaneous tumor, singular non-cutaneous cases have since been reported in bone. We aimed to investigate the clinicopathological features of this variant across all anatomic sites through a large multi-institutional study. We complied a total of 24 myoepitheliomas with syncytial growth from our files. The tumors occurred in 12 male and 12 female patients (M:F = 1:1), with a median age of 31 years (range, 9-69 years). While the majority of tumors (75%, n = 18) occurred in skin, a significant subset (25%, n = 6) arose in non-cutaneous sites, including bone (n = 3), bronchus/trachea (n = 2), and interosseous membrane of tibia/fibula (n = 1). Tumor size ranged from 0.4 to 5.9 cm. Clinical follow-up (7 patients; range 14-202 months; median 56.5 months) showed a single local recurrence 8 years after incomplete skin excision but no metastases; all patients were alive at the time of last follow-up without evidence of disease. Histologically, all tumors were pink at low-power and characterized by a syncytial growth of bland ovoid, spindled, or histiocytoid cells with eosinophilic cytoplasm and prominent perivascular lymphoplasmacytic inflammation. One-third displayed adipocytic metaplasia (8/24). Rare cytologic atypia was seen but was not associated with increased mitotic activity. All tumors expressed S100, SMA, and/or EMA. Keratin expression was absent in most cases. Molecular analysis was performed in 16 cases, all showing EWSR1-rearrangments. In total, 15/15 (100%) harbored an EWSR1::PBX3 fusion, whereas 1 case EWSR1 FISH was the only molecular study performed. Syncytial myoepithelioma is a rare but recognizable morphologic variant of myoepithelioma which may have a predilection for skin but also occurs in diverse non-cutaneous sites. Our series provides evidence supporting a reappraisal of the term "cutaneous syncytial myoepithelioma," as 25% of patients in our series presented with non-cutaneous tumors; thus, we propose the term "syncytial myoepithelioma" to aid pathologist recognition and avoidance of potentially confusing terminology when referring to non-cutaneous examples. The behavior of syncytial myoepithelioma, whether it arises in cutaneous or non-cutaneous sites, is indolent and perhaps benign with a small capacity for local recurrence.

Intraoral salivary lymphoepithelial carcinoma: clinicopathologic and immunophenotypic characterization of 3 cases indicates elevated programmed death-ligand 1 expression

Intraoral salivary lymphoepithelial carcinoma (ISLEC) is a rare malignancy with programmed death-ligand 1 (PD-L1) expression levels that have been greatly understudied. We examined the clinicopathologic and immunophenotypic characteristics, including PD-L1 levels, of 3 cases of ISLEC. We searched the archives of 2 oral and maxillofacial pathology laboratories for specimens diagnosed as ISLEC between 1985 and 2022. We collected patient demographic and clinical data. Immunostaining for AE1/AE3, CK7, CD3, CD20, p16, p53, Ki67, and PD-L1 (SP263), as well as Epstein-Barr virus-encoded small RNAs (EBER) in situ hybridization (ISH) were performed. All 3 cases affected males aged 42 to 84 years (median=61y) and involved the floor of the mouth, soft palate/uvula, and tongue. The lesions showed diffuse infiltration by non-keratinizing sheets and islands of undifferentiated carcinoma cells with associated dense lymphoplasmacytic inflammation. Immunohistochemically, all tumors showed AE1/AE3 positivity, selective p53 staining, and negativity for CK7 and p16. Ki67 highlighted 20%-80% of lesional cells. The inflammatory infiltrate comprised a mixed population of T and B lymphocytes. EBER ISH was positive in one case. All ISLECs displayed membranous, focal-to-diffuse, PD-L1 staining with tumor proportion score > 95% in two and 40-50% in the third case. The clinicopathologic and immunophenotypic characteristics of the cases we examined highlight the rarity of ISLEC and indicate overall high PD-L1 levels in this type of malignancy, rendering patients with ISLEC potential candidates for targeted α-PD-1/PD-L1 immunotherapy.

Disseminated Rasamsonia argillacea infection in a dog

ABSTRACT Case history A 4-year-old, male neutered Borzoi presented for unlocalised pain and frequent episodes of vocalisation. Clinical findings Pain was localised to the lumbar spine and radiographs revealed a L3–L4 lesion consistent with discospondylitis. The dog was treated for presumptive bacterial discospondylitis with surgical debridement, spinal stabilisation, and cephalexin. Samples collected from the affected intervertebral disc at the time of surgery revealed lymphoplasmacytic inflammation with no causative agent identified on histopathology or bacterial culture. After an initial period of improvement, signs recurred despite an 8-week antibiotic course, with the development of inappetence, weight loss, polydipsia, and polyuria. Repeat radiographs revealed a new cervical intervertebral lesion, and concurrent pyelonephritis was diagnosed based on blood and urine results. Fungal culture of urine resulted in growth of Rasamsonia argillacea species complex and disseminated fungal disease was clinically diagnosed. Antifungal treatment was commenced, however the dog deteriorated, and euthanasia was performed. Pathological findings Multifocal white plaques were grossly visualised in the spleen, mesenteric lymph nodes, cervical vertebrae, and kidneys. Periodic acid-Schiff-positive, fine, parallel-walled, occasionally branching, septate hyphae 5–10 μm in diameter, and conidia 5–7 μm in diameter were found on sectioning all organs. R. argillacea species complex was identified by fungal culture of urine and was considered the species of fungal organism seen histologically. The isolate was subsequently confirmed as R. argillacea by DNA sequencing. Diagnosis Disseminated Rasamsonia argillacea infection. Clinical relevance Rasamsonia argillacea species complex is a recognised invasive mycosis in veterinary medicine, with disseminated disease causing significant clinical complications and death. This is believed to be the first report of infection caused by R. argillacea in a dog in Australasia and highlights the importance of awareness of a potential fungal aetiology in dogs with discospondylitis. Abbreviations: CLSI: Clinical and Laboratory Standards Institute; CRI: Constant rate infusion; MEC: Minimum effective concentration; MIC: Minimum inhibitory concentration; PAS: Periodic acid-Schiff

Histopathology and virulence of an in vitro-adapted Trypanosoma evansi TEDC 953 strain (Thailand isolate) in mice.

Trypanosoma evansi is a blood and tissue protozoan parasite affecting domestic and wild animals. The T. evansi Thai strain, namely, T. evansi from dairy cattle number 953 (TEDC 953) strain, has been successfully isolated from dairy cattle and cultivated in vitro. The in vitro-cultivated parasite is useful for biological studies, evaluation of novel chemotherapeutic agents, and production of antigens for diagnostic tests. This study aimed to observe the histopathology and virulence of an in vitro-adapted T. evansi TEDC 953 strain in vivo. The histopathology and virulence of the TEDC 953 strain were clarified in mice. Six mice were infected with 1 × 105 trypomastigotes of TEDC 953 strain intraperitoneally, and four mice were in the negative control. Parasitemia was monitored daily, and the mice were euthanized on 30 days post-infection (DPI). Internal organs were collected for histopathological examination using hematoxylin and eosin staining. Histopathological lesions were found in the liver, lung, heart, kidney, spleen, and brain of the inoculated mice. The main histopathological feature was lymphoplasmacytic inflammation in parenchyma and perivascular areas of multiple organs, and the severity of histopathological changes was related to the presence of trypomastigotes in the regional vessels. Granulomatous inflammation was seen in meninges, pleura, renal capsule, renal pelvis, and spleen of some infected mice. Four mice died at 17, 24, 26, and 27 DPI with an average parasitemia of 4.05 × 1011 trypomastigotes/mL. The average survival time was 23.5 DPI (mice = 4). This study confirmed that the TEDC 953 strain is infectious and pathogenic in mice after the continuously cultivated in vitro. To replace the use of experimental animals, the in vitro-cultivated parasite can be used instead in further studies.

PO-02-059 INFLAMMATORY REACTION TO ANTIBIOTIC ELUTING POUCH MASQUERADING AS RECURRENT CARDIAC IMPLANTABLE ELECTRONIC DEVICE INFECTION

Absorbable antibacterial envelopes mitigate risk of pocket infections during repeat cardiac implantable electronic device (CIED) procedures. Despite use of antibacterial envelopes, risk of CIED infection persists. However, hallmark signs of CIED infection including incisional erythema, drainage, and wound dehiscence overlap with a less common clinical entity – allergic reaction. To present a case of recurrent CIED wound dehiscence secondary to an inflammatory response to the antibacterial envelope proven with histological evaluation. N/A A 52-year-old male with remote aortic valve replacement complicated by complete heart block and a dual chamber pacemaker (DC PPM) underwent generator change with use of a Tyrx antibacterial pouch. One week later, he developed partial wound dehiscence and cloudy incisional drainage. The patient was started on antibiotic therapy and underwent percutaneous system extraction with placement of an externalized right ventricular lead. Pocket cultures were negative. A contralateral DC PPM was inserted with a Tyrx pouch. The patient completed a course of antibiotics. Within two weeks of placement, he presented with recurrent wound dehiscence. The new device was removed with a pathologic specimen obtained from the presumably infected pocket and an externalized pacing lead was placed. Cultures were again negative. The pathologic specimen demonstrated foreign body response with lymphoplasmacytic and focal neutrophilic inflammation most consistent with allergic reaction. The patient underwent implantation of a low-lateral left-sided DC PPM distant from the prior site without the use of a Tyrx antibacterial envelope. The patient was discharged without antibiotics with no evidence of infection or inflammation at the new site over a follow up period of 6-months. Allergic reaction to Tyrx antibiotic envelope should be considered with wound dehiscence, particularly if recurrent. Tissue biopsy with foreign body response can elucidate an allergic mechanism.

Latent class analysis of structured histopathology in prognosticating surgical outcomes of chronic rhinosinusitis with nasal polyps in Singapore.

Structured histopathology profiling is recommended when reporting chronic rhinosinusitis with nasal polyp (CRSwNP) tissue. The objective of this study is to identify features in structured histopathology that predict outcome after functional endoscopic sinus surgery (FESS) in a cohort of CRSwNP patients from Singapore. Latent class analysis was performed on structured histopathology reports of 126 CRSwNP patients who had undergone FESS. Outcome measures were polyp recurrence, need for systemic corticosteroids, revision surgery or biologics, and disease control at 2 years post-FESS. Three classes were identified. Class 1 was characterised by mild, predominantly lymphoplasmacytic inflammation. Class 2 comprised of 100 eosinophils/HPF, hyperplastic seromucinous glands, mucosal ulceration and mucin containing eosinophil aggregates and Charcot-Leyden crystals. Classes 2 and 3 were significantly associated with uncontrolled disease at 2 years post-FESS. Class 3 was additionally associated with the need for systemic corticosteroids. Eosinophil count, degree of inflammation, predominant inflammatory type, hyperplastic seromucinous glands, mucosal ulceration and mucin containing eosinophil aggregates and Charcot-Leyden crystals predicted need for systemic corticosteroids and uncontrolled disease at 2 years post-FESS. The presence of &gt;100 eosinophils/HPF should be reported, as this subset of tissue eosinophilia was associated with less favourable outcomes after FESS.

Clinical, radiographic and histopathologic features of early-onset gingivitis and periodontitis in cats (1997–2022)

This study aimed to characterize the clinical, radiographic and histopathologic features of early-onset gingivitis (EOG) and periodontitis in cats. The medical records database was searched for cats diagnosed with histologically confirmed EOG or periodontitis from 1997 to 2022. Information such as medical history, lifestyle factors, clinical presentation, radiographic and histopathologic features were included for 27 client-owned cats. Response to treatment and long-term follow-up was also recorded. Moderate-to-severe periodontal disease was radiographically confirmed in 78% (21/27) of cats with moderate-to-severe EOG, compared with the evidence of periodontal disease noted in 30% (8/27) of cases during awake oral examination. Horizontal bone loss, along with missing teeth, were the predominant radiographic features noted in 89% (24/27) of cases. The predominant histopathologic feature was moderate-to-severe, erosive-to-ulcerative, neutrophilic and lymphoplasmacytic inflammation with varying degrees of epithelial and stromal hyperplasia. Two cats developed feline chronic gingivostomatitis (FCGS)-like lesions, and seven cats exhibited worsening of aggressive periodontitis (AP). Lack of improvement in the severity of gingivitis or clinical signs evident at the first follow-up appointment was significantly associated with progression of disease (P = 0.004). The results of this study demonstrate the importance of oral evaluations in cats as early as 6 months of age. For cats exhibiting substantial gingivitis, an anesthetized evaluation, periodontal treatment and long-term monitoring are recommended. Given the high frequency of moderate-to-severe periodontitis encountered in these cats, clients should be informed about the potential need for tooth extractions. EOG may progress to AP. Finally, this study suggests that there could be a link between EOG and FCGS; however, further studies are needed to better characterize this condition and establish any potential link between the two entities.

S2919 Bile Duct Injury Due to Ketamine Use

Introduction: Ketamine is used routinely in the hospital for anesthesia, but is also used recreationally for its hallucinogenic and dissociative side effects. Chronic recreational use has been linked to bile duct damage and ulcerative cystitis. We report a case of ketamine induced sclerosing cholangiopathy. Case Description/Methods: A 42-year-old Cantonese woman with past medical history of bilateral hydronephrosis with stents leading to chronic kidney disease presented with abdominal pain associated with abnormal transaminases. Alkaline phosphatase was high at 1,017 IU/L with gamma glutamyl transferase of 2,310 IU/L with normal bilirubin. Abdominal imaging showed diffuse dilatation of the common bile duct. Viral serologies and anti-mitochondrial antibody were negative. She reported chronically elevated liver tests of unknown etiology. Social history was notable for prior alcohol abuse. She denied family history of liver diseases. Her pain resolved and plan was for outpatient follow-up, but she re-presented with sepsis with a rise in bilirubin to 2.9 mg/dL (Table 1). Given prior abnormal imaging, a magnetic resonance cholangiopancreatography was obtained, which showed increased intra- and extrahepatic bile duct dilation with irregular appearance of the central intrahepatic ducts with possible stricture. Differential diagnoses were recurrent pyogenic cholangitis, sclerosing cholangitis, and IgG4 disease. Her IgG level was high at 2,779 mg/dL with IgG4 elevated at 213 mg/dL. Liver biopsy showed chronic cholestatic liver injury consistent with sclerosing cholangitis (Image 1). IgG4 stain was negative. Upon further investigation, patient admitted to at least a decade of daily ketamine use, which was likely the culprit of both her kidney and liver diseases. Discussion: Due to her age, race, gender and rarity of ketamine induced cholangiopathy, she was not directly asked about ketamine use. Since the early 2000s, ketamine has emerged as the illicit drug of choice in Hong Kong and has seen increased use throughout Asia. The biliary damage from ketamine has been studied by a Chinese group that found 62% of the 257 chronic ketamine users had biliary tract anomalies. The greater the alkaline phosphatase, the higher the likelihood of finding biliary tract anomalies on imaging. Ketamine cessation has resulted in normalization of liver tests and imaging, however worsening cholangiopathy has been seen despite abstinence. In patients who present with unexplained cholangiopathy, chronic ketamine use should be considered.Figure 1.: Liver biopsy: A mild lymphoplasmacytic inflammation is noted in some triads with focal and mild interface activity. The bile ducts are injured (irregular contour, unevenly distributed nuclei, intracytoplasmic vacuoles) with focal periportal cholestasis. Immunohistochemical stain for keratin 7 confirms predominantly periportal cholestatic hepatocytes. Keratin 19 shows widespread loss of canals of Hering and focal bile duct loss. Rhodanine stain confirms periportal hepatocellular copper accumulation compatible with a chronic cholestatic process. Table 1. - Patient's hepatic function panels during initial encounter, subsequent encounter, and at least 6 months after subsequent encounter Liver Tests Reference Range & Units Initial Hospitalization Subsequent Hospitalization Most Recent Liver Tests Total bilirubin 0.2 – 1.2 mg/dL 0.8 2.9 4.5 Direct bilirubin 0 – 0.5 mg/dL 0.7 1.8 3.3 Aspartate aminotransferase 5 – 34 IU/L 75 104 88 Alanine transaminase 0 – 37 IU/L 74 129 91 Alkaline phosphatase 40 – 150 IU/L 1017 1106 845 Gamma glutamyl transferase 12 – 43 IU/L 2310 2516 1897