IgG4-mediated sclerosing fibroinflammatory disease presenting as inflammatory breast malignancy

IgG4-mediated sclerosing fibroinflammatory disease is a rare systemic disease which has the ability to form masses in multiple organs and may mimic malignancy. In this case we describe a 53-year-old female who presented with clinical and imaging findings in her right breast consistent with inflammatory breast carcinoma and associated right axillary nodal mass. She underwent CT which also uncovered a left thyroid mass and suggested both masses were possibly malignancies. She proceeded to ultrasound-guided core biopsy of each, which showed an appearance characteristic of IgG4-mediated sclerosing fibroinflammatory disease. The patient was treated with steroids with good outcome. This is the first described case of this condition presenting in this way to our knowledge and this diagnosis should be considered in patients with similar presentations.