IgG4-related disease: Case report and 6-year follow-up of an elusive diagnosis mimicking malignancy.

Key Clinical Message: IgG4-related disease is a rare and emerging pathology, characterized by the appearance of pseudotumors. Due to the ability to mimic other pathologies, it is essential to consider it as a differential diagnosis in multisystemic processes. The diagnosis is challenging, requiring a multidisciplinary approach, to minimize the associated morbidity and mortality.