IgG4 –related disease is a new evolving immune-mediated diseasethat was recently discovered, with  awide range of clinical features that involves multiple systems with newclinical presentations being discovered every day, diagnosis depends onclinical and characteristic histopathology findings  upon biopsy that shows dense lymphoplasmacyticinfiltration of IgG 4 plasma cells associated with storiform fibrosis ,since itcan cause tumor like masses ,it could mimic malignancies as lymphoma.    We report a 58 years oldMalaysian gentleman with a background history of hypertension, chronic kidney disease,who was in his usual state of health till 2 years back when he started todevelop slowly progressive painless cervical lymphadenopathy ,parotid gland enlargement,bilateral orbital swelling and fatigue, ,patient  denied any fever, night sweats or weight loss,Seen by many specialties through these 2 years with multiple emergency departmentvisits with no  good response toantibiotics trial therapy and no conclusive diagnosis was made.Ultrasound neck confirmed the presence of multiple submaxillary, salivaryand parotid gland enlargement, fine needle aspiration of left maxillary lymph nodewas inconclusive, follow up ultrasound showed increase in the size of theaffected lymph nodes.

 Infections as EBV,CMV ,HIVand  tuberculosis, ruled out,Sjogrenssyndrome versus lymphoma  was suspectedat that stage but patient had negative ANA,ANTI RO/LA .Thenafter one year of extensive investigations patient was admitted with painlessobstructive jaundice,pruririts and decreased appetited had a cholestaticpattern liver impairment, with negative hepatitis serology and negativescreening for autoimmune hepatitis,MRCP done that showed a  Pancreatic head mass lesion causing obstructionof the pancreatic  and bile ducts, Enlargedperipancreatic lymph nodes, Multiple parenchymal lesions of both kidneys, Circumferentialthickening and diffusion restriction of the wall of a limited part of the aortainferior to the renal arteries, impressive of focal aortitis The possibilitiesof lymphoma  versus IgG4-related disease wereconsidered as a highly probable diagnosis. Subsequentblood  studies were performed demonstratingelevated IgG-4 (1,980  mg/dL), EUS- FNA of pancreatic head mass ruled outpancreatic head malignancy ,so right groin excisional lymph node biopsy wasdone `that showed Increased nodal IgG4 plasmacells consistent with IgG4-related disease (morethan 30/hpf).Flow cytometry was not suggestive of lymphoma.Diagnosis of IgG4 –related disease was made after discussion ina multidisciplinary team and patient was started on pulse steroid therapy for 3days followed by oral prednisolone 1mg/kg.Follow up visit revealed marked improvement in the patient’s symptoms,normalization of liver function tests and decrease in IgG 4 level from 1,980 to400 mg/dl,so steroids were tapered down by 5mg every week and azathioprineadded.

 It is important to note that IgG 4-related  disease is a mimicker of malignancy, This casehighlights the importance of keeping high index of suspicion for IgG 4-related asdelay in diagnosis as what happened with this patient could lead to irreversiblefibrosis and organ damage,clinicians should be more aware of this new diseaseentity ,putting into consideration that it istreatment responsive,so early diagnosis could lead to decrease morbidity andmortality.