Paediatric Collagenous Gastritis with Transient Response to Steroid Therapy.

INTRODUCTION: Collagenous gastritis is a rare condition characterised by subepithelial collagen deposition and an inflammatory infiltrate. Despite being first described in 1989, the pathogenesis remains poorly understood. Clinical manifestation and histological features have been extensively described in the literature; however, treatment strategies are largely based on expert opinion and show variable efficacy. CASE DESCRIPTION: We describe a case of paediatric collagenous gastritis presenting with dyspepsia, nausea and iron deficiency anaemia initially attributed to menorrhagia. Endoscopy demonstrated nodular gastritis and histology confirmed the diagnosis. The patient had initial symptomatic improvement with budesonide; however, this was not sustained. CONCLUSION: This case highlights the importance of considering collagenous gastritis as a cause of iron deficiency anaemia, particularly in young female patients. It also demonstrates the management challenges in achieving sustained clinical response, reflecting the limited evidence base guiding management. LEARNING POINTS: Collagenous gastritis is a rare but important cause of iron deficiency anaemia, particularly in young patients with persistent gastrointestinal symptoms.Alternative causes of iron deficiency beyond menstruation should be considered in young female patients, with early consideration for endoscopy.Symptomatic improvement with corticosteroids may be transient and sustained clinical or histological remission remains difficult to achieve.