A104 INVISIBLE COLONIC MALIGNANCY AND POSSIBLE IDIOSYNCRATIC DRUG-INDUCED LIVER INJURY FROM VEDOLIZUMAB IN A PATIENT WITH ULCERATIVE COLITIS, PRIMARY SCLEROSING CHOLANGITIS AND AUTOIMMUNE HEPATITIS OVERLAP SYNDROME

Background

Inflammatory bowel disease (IBD) is characterized by chronic inflammation of the gastrointestinal tract. Due to an increased risk of developing colorectal cancer, regular surveillance for dysplastic lesions via colonoscopy is recommended. Invisible dysplasia is the abnormal development of cells noted on pathology with no visible lesion seen during colonoscopy. Primary sclerosing cholangitis (PSC) is an immune-mediated liver disease leading to progressive stricturing and fibrosis of the bile ducts. There is significant association between PSC and IBD, as up to 80% of patients with PSC having underlying IBD. Drug induced liver injury (DILI) is a common cause of acute liver failure in most Western countries. Most cases of DILI are self-limited, with resolution of laboratory and clinical findings after cessation of the offending agent.

Purpose

To describe a case of invisible colonic malignancy and possible idiosyncratic drug-induced liver injury from vedolizumab (VDZ) in a patient with ulcerative colitis (UC), PSC and autoimmune hepatitis (AIH) overlap syndrome.

Method

Patient consent was obtained. Information from electronic records was extracted, including admission notes and procedural reports. A literature review was performed using Pubmed.

Result(s)

A 32-year-old Caucasian female with UC on VDZ with PSC and AIH had multiple colonoscopies performed demonstrating multifocal low-grade dysplasia. However, she remained resistant to surgery. She presented to clinic with tea-coloured urine, fatigue, and scleral icterus. Investigations revealed conjugated hyperbilirubinemia with elevation in hepatocellular liver enzymes. Imaging was consistent with large duct PSC, and liver biopsy showed grade 2 chronic hepatitis raising the possibility of large bile duct obstruction. She underwent liver transplant assessment and VDZ was held. Her bilirubin and liver enzymes recovered. Given multiple colonoscopies showing multifocal dysplastic changes and the patient declining other biologics, she would ultimately undergo total proctocolectomy with end ileostomy. Pathology demonstrated mucinous adenocarcinoma with a signet ring component.

Conclusion(s)

Both mucinous adenocarcinoma and signet ring carcinoma are more aggressive malignancies associated with poor prognosis. Found more often in younger patients, they are often diagnosed in later stages with lymphovascular invasion. Here, there was no evidence of metastases in any of the 40 lymph nodes examined, which indicated more favourable prognosis.

The mechanism by which VDZ potentially causes liver injury is unknown. Multiple therapies for PSC-AIH overlap and IBD were entertained as causative agents. However, significant improvement in clinical symptoms and serologic parameters following cessation of VDZ was temporally suggestive.

This case simultaneously highlights the importance of both timely colectomy in IBD patients with high-risk features during surveillance and early recognition and cessation of potential causative medications which induce liver injury.

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Disclosure of Interest

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Predicting XAFS scattering path cumulants and XAFS spectra for metals (Cu, Ni, Fe, Ti, Au) using molecular dynamics simulations

The ability of molecular dynamics (MD) simulations to support the analysis of X-ray absorption fine-structure (XAFS) data for metals is evaluated. The low-order cumulants (ΔR, σ(2), C3) for XAFS scattering paths are calculated for the metals Cu, Ni, Fe, Ti and Au at 300 K using 28 interatomic potentials of the embedded-atom method type. The MD cumulant predictions were evaluated within a cumulant expansion XAFS fitting model, using global (path-independent) scaling factors. Direct simulations of the corresponding XAFS spectra, χ(R), are also performed using MD configurational data in combination with the FEFF ab initio code. The cumulant scaling parameters compensate for differences between the real and effective scattering path distributions, and for any errors that might exist in the MD predictions and in the experimental data. The fitted value of ΔR is susceptible to experimental errors and inadvertent lattice thermal expansion in the simulation crystallites. The unadjusted predictions of σ(2) vary in accuracy, but do not show a consistent bias for any metal except Au, for which all potentials overestimate σ(2). The unadjusted C3 predictions produced by different potentials display only order-of-magnitude consistency. The accuracy of direct simulations of χ(R) for a given metal varies among the different potentials. For each of the metals Cu, Ni, Fe and Ti, one or more of the tested potentials was found to provide a reasonable simulation of χ(R). However, none of the potentials tested for Au was sufficiently accurate for this purpose.

Immunoglobulin delta expression in Burkitt's lymphoma cell lines

Eighteen Burkitt's lymphoma (BL) cell lines were analyzed for rearrangement and expression of the delta gene. None had rearrangement of the delta gene locus within the 9.0-kb BamHI restriction fragment. Cell lines that expressed the delta gene contained both mu alleles, with at least one productively rearranged. Thirteen of 18 cell lines had detectable transcripts hybridizing with the delta probe. In 10 of the 13 cell lines with delta transcripts, cytoplasmic delta chains were detected, but only two of these expressed delta chains strongly on the surface. All 13 lines made cytoplasmic mu chains, and all except one made cytoplasmic light chains. Surface IgM was detected in all except two of the 13 cell lines. Although BL has generally been considered not to express IgD, except in occasional cases, previous studies have been confined to examination of the cell surface. Many of the cell lines that we examined express delta mRNA transcripts as well as produce cytoplasmic delta chains but no detectable surface IgD. This suggests that delta chains are detectable in the cytoplasm prior to being apparent on the surface. Our findings argue against an origin of BL from germinal center cells since IgD is almost totally lacking in normal B cells present in germinal centers.