IgG4-related Retroperitoneal Fibrosis: An Emerging Masquerader With a Sinister Presentation.

ABSTRACT

OBJECTIVE: Retroperitoneal fibrosis (RPF) is a rare proliferative fibro-inflammatory disease involving the soft tissues of the retroperitoneum. IgG4 related retroperitoneal fibrosis is an emerging entity which needs to be distinguished from idiopathic RPF. We describe a clinical case of IgG4 related RPF highlighting the importance of clinching this diagnosis. METHODS: A 70 year old female was referred to the outpatient department of our institute with complaints of fatigue, bilateral flank pain and loss of appetite for the past 1 month. The CT and PET scan demonstrated a uniformly enhancing bulky retroperitoneal mass causing bilateral hydroureteronephrosis. The biopsy from the mass lesion revealed IgG4 related disease. The patient was started on corticosteroids after percutaneous nephrostomy placement. RESULTS: Three months post induction of therapy, repeat PET-CT shows resolution of the mass with no FDG avid lesion. Serum IgG4 levels were reduced to normal (27 mg/dL) suggestive of response to treatment. The percutaneous nephrostomies were removed and the patient is doing well on maintenance dose of corticosteroids for her disease. CONCLUSION: The availability of serum IgG4 levels for monitoring treatment response and follow-up can curtail the repeated radiological imaging and associated contrast exposure as compared to idiopathic RPF. Secondly, the diagnosis of IgG4-related RPF shall alert the clinician to look out for extra-retroperitoneal diseases on follow up of this multi-organ disease.