sarcoidosis is a rare condition with a prevalence of 4.46.3 patients per 100,000 personyears in australia , a figure similar to that of the united state 1 , 2 .
it is a multisystem granulomatous disorder of unknown etiology predominantly affecting young and middleaged adults 3 , 4 .
diagnostic criteria are based on a compatible clinical and radiological features supported by the histological evidence of noncaseating granulomas in the affected tissues , and the exclusion of other known causes of granulomatous inflammation 3 , 4 . pulmonary infiltration and hilar lymphadenopathy
are the most common findings in more than 90% of cases , and transbronchial lung biopsy has been the recommended diagnostic procedure 3 , 4 .
other organs involvement includes skin , eyes , liver , spleen , heart , musculoskeletal system , gastrointestinal tract , bone marrow , and the central nervous system .
anemia has been reported in cases of sarcoidosis with the frequency ranging from 3.4% to 31% with a variety of explanations .
these include hypersplenism , burden of chronic disease , autoimmunity , and bone marrow infiltration 5 .
histological evaluation of extrapulmonary sarcoidosis depends on the site of involvement , but its diagnosis is rarely made via bone marrow biopsy 6 .
features which may suggest bone marrow infiltration in sarcoidosis include extrapulmonary involvement and varying degree of cytopenia 7 .
the characteristic granuloma in sarcoidosis is a noncaseating focal aggregation of macrophages or epithelioid cells , with or without multinucleated giant cells .
its presence confirmed the diagnosis of a nonnecrotizing granuloma , in particular sarcoidosis 8 , 9 .
a 40yearold caucasian woman presented with a threemonth history of polyuria , malaise , and weight loss .
she had been receiving interferon ( ifn ) 1 for multiple sclerosis for the previous 12 years .
investigations revealed moderate normocytic anemia , hypercalcemia , hyperglobulinemia , and acute kidney injury ( table 1 ) .
her initial chest radiograph was normal , but further investigation with computed tomography showed diffuse lymphadenopathy in her chest and abdomen .
a bone marrow trephine biopsy demonstrated noncaseating granulomas ( figs 1 and 2 ) and asteroid bodies ( black arrows in fig .
her ifn treatment was discontinued , and she was commenced on prednisolone ( 60 mg daily ) with a slow tapering regimen over 6 months .
her renal function and hypercalcemia recovered promptly , and her hemoglobin normalized at 12th week .
summary of laboratory investigation results egfr , estimated glomerular filtration rate ; pth , parathyroid hormone ; k / l , kappa / lambda light chain ; ace , angiotensin converting enzyme ; si , systme international .
histopathological section of a trephine bone marrow biopsy revealing a noncaseating granuloma composed of aggregation of multinucleated giant cells containing asteroid bodies ( arrowed ) .
the noncaseating granuloma in the center ( black arrow ) is surrounded by pale pink amorphous material with scattered mononuclear cells interspersed throughout with some giant cells .
there is also a surrounding cuff composed of reactive cells such as eosinophils and neutrophils .
a second granuloma is visible in the periphery containing a langhans giant cell ( white arrow ) .
a cardinal feature of sarcoidosis is the presence of cd+ t cells which display unregulated interaction with the antigenpresenting cells to initiate the formation and maintenance of noncaseating granulomas 10 .
oligoclonal  tcell repertoire observed in sarcoidosis suggests that the triggering antigens favor the progressive accumulation and activation of selective cd4 tcell clones 11 .
this in turn leads to the preferential differentiation of the th1 helper cells which predominantly secretes interleukins ( il)2 and il12 12 .
these ils have been found in higher quantity in the bronchoalveolar lavage fluid of patients with sarcoidosis and subsequently stimulate increased production of ifn and macrophage activation .
it has a different structure and binds to a different receptor than the type i ifn (  and  ) , and its gene is located on a different chromosome 12 .
although endogenous ifn has been implicated in the pathogenesis of sarcoidosis , there is little evidence for other types of ifns 11 .
the incidence of sarcoidosis is increasing with the use of type i ifn ( ifn , ifn ) for various conditions such as hepatitis b , hepatitis c , lymphoproliferative malignancy , and multiple sclerosis 13 , 14 , 15 . to date , 60 cases of sarcoidosis have been reported in the english literature in association with the use of ifn , in comparison with only six cases which were associated with the use of ifn 
 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 .
the mean onset of development of sarcoidosis was 11.4 months after initiation of ifn therapy ( ranged 160 months ) , which is much earlier than our patient 13 .
the pattern of system involvement is similar to that of the idiopathic form of sarcoidosis .
only one case of the six is proven to have bone marrow involvement with a bone marrow biopsy 16 .
ifninduced sarcoidosis exhibits a relatively mild disease course that usually resolves with cessation of ifn treatment . a small proportion of patients required systemic corticosteroid 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 .
it is a diagnosis that should be considered in patients receiving ifn therapy of any type who present with anemia and multiorgan dysfunction .
the overall pattern of organs involvement in sarcoidosis associated with ifn is similar to that of the idiopathic form .
 key clinical messagesarcoidosis is a diagnosis that should be considered in patients receiving interferon therapy , who present with anemia and multiorgan dysfunction regardless of the duration of their treatment . when sarcoidosis is suspected , bone marrow biopsy should be considered especially for cases predominant by extrapulmonary features . 
Introduction
Case Presentation
Discussion
Conclusion
Conflict of Interest