S3708 Delayed Diagnosis of Collagenous Colitis in a Young Woman With Prior SARS-CoV-2 Infection

Introduction: Collagenous colitis (CC) is a subtype of microscopic colitis characterized by chronic, watery, non-bloody diarrhea, commonly affecting individuals over the age of 60. Diagnosis can be challenging due to non-specific symptoms and often normal endoscopic appearance. While its pathogenesis is not fully understood, recent evidence suggests a possible association between CC and preceding SARS-CoV-2 infection. Patients with CC are also susceptible to superimposed infections. We present a case of delayed CC diagnosis in a woman with persistent diarrhea following SARS-CoV-2 infection, complicated by Clostridioides difficile (CD) infection. Case Description/Methods: A 61-year-old woman presented with 7-months of persistent watery diarrhea, a 7-kg weight loss, and decreased oral intake. She recalled a prior episode of severe diarrhea occurring 4 weeks after a SARS-CoV-2 infection. Initial esophagogastroduodenoscopy (EGD) and colonoscopy showed non-specific chronic colitis, and she was empirically treated with mesalamine without improvement. She later presented to our hospital with diarrhea, myalgias, fever, and generalized weakness, attributed to a viral-like illness. Labs revealed positive stool leukocytes; CD polymerase chain reaction (PCR) and enteric stool studies were negative. Repeat colonoscopy and EGD were grossly normal, but biopsies revealed active colitis with crypt abscesses. Biopsies were sent to a tertiary center for further review. Her symptoms improved with supportive care, and she was discharged. Four days later, she returned with worsening diarrhea. Fecal calprotectin was elevated at 646 μg/g and repeat CD PCR was now positive. She was treated with oral vancomycin, with subsequent improvement. Final pathology report revealed irregular epithelial injury and a thickened subepithelial collagen enveloping microvasculature, without increased intraepithelial lymphocytes consistent with CC. She was treated with oral budesonide and at 8 weeks follow-up, reported marked improvement. Discussion: This case illustrates the diagnostic challenges of CC, particularly when obscured by nonspecific pathology and superimposed infections. A preceding SARS-CoV-2 infection may have triggered disease onset. Timely histopathologic confirmation is crucial, as early treatment can lead to rapid clinical resolution.