Mucosa-Associated Lymphoid Tissue Lymphoma Masked as Gastric Varices With Acute Upper Gastrointestinal Bleeding: A Case Report.

Extra-nodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT) is uncommon and difficult to diagnose due to varied clinical presentations and endoscopic appearances masquerading as other pathology. Rarely, it has been associated with acute upper gastrointestinal (GI) bleeding. We report on a 60-year-old male who presented with an acute upper GI bleed and endoscopic findings suggestive of isolated gastric varices (GV), ultimately determined to be MALT lymphoma. Complete remission was achieved with radiation therapy, with no recurrence at a 12-month follow-up. This case highlights a unique clinical and endoscopic presentation of MALT lymphoma which providers should be aware of. We emphasize the use of endoscopic ultrasound (EUS) evaluation for accurate diagnosis.

Normal Ranges of Thiopurine Methyltransferase Activity Do Not Affect Thioguanine Nucleotide Concentrations With Azathioprine Therapy in Inflammatory Bowel Disease.

Background: Thiopurine methyltransferase (TPMT) activity influences azathioprine conversion into active metabolite 6-thioguanine nucleotide (6-TGN). Low TPMT activity correlates with high 6-TGN and risk for myelosuppression. Conversely, normal-to-high TPMT activity may be associated with low 6-TGN and drug resistance, the so-called hypermetabolizers. Our aim was to identify the effect of normal-to-high TPMT activity on 6-TGN concentrations in an inflammatory bowel disease population. Methods: A retrospective chart review of patients aged ≥18 with inflammatory bowel disease, on azathioprine, with documented TPMT activity and 6-TGN concentration was performed. Correlations were evaluated via the Spearman rho correlation coefficient. Linear regression was used to determine the effect of TPMT activity on 6-TGN accounting for confounders. Relationships between TPMT activity, drug dose, and 6-TGN levels were defined via average causal mediation effects. Results: One hundred patients were included. No correlation was observed between TPMT activity, azathioprine dosing, and metabolite concentrations. Overall, 39% of the cohort had a therapeutic 6-TGN level of >230 pmol/8 × 108 red blood cells (RBCs). No patient under 1 mg/kg achieved a therapeutic 6-TGN level, whereas 42% of patients taking 2.5 mg/kg did. The median 6-TGN concentration was higher for those in remission (254 pmol/8 × 108 RBCs, interquartile range: 174, 309) versus those not in remission (177 pmol/8 × 108 RBCs, interquartile range: 94.3, 287.8), though not significantly (P = 0.08). Smoking was the only clinical factor associated with 6-TGN level. On multivariate linear regression, only age, azathioprine dose, and obese body mass index were predictive of metabolite concentration. Conclusions: Variations within the normal range of TPMT activity do not affect 6-TGN concentration.