Pemphigus Vulgaris With an Elevated Faecal Calprotectin Mimicking Inflammatory Bowel Disease: A Case Report

We present the case of a 57-year-old woman with severe, recurrent oral ulceration and weight loss. Faecal calprotectin was markedly elevated at 1,246 µg/g, initially raising suspicion of inflammatory bowel disease with oral manifestations. However, endoscopic evaluation revealed no gastrointestinal pathology. Oral biopsy with direct immunofluorescence revealed pemphigus vulgaris. This case illustrates two important reminders for general physicians. Firstly, approximately half of all patients with pemphigus vulgaris present with oral lesions alone, without cutaneous involvement, for months before diagnosis. Secondly, faecal calprotectin elevation can result from swallowing oral inflammatory exudate rather than bowel pathology. Clinicians should consider autoimmune blistering disorders in patients with unexplained severe oral ulceration unresponsive to standard treatments, and interpret faecal calprotectin within the complete clinical context.