sarcoidosis is a multisystemic , granulomatous disease of unknown etiology that may affect any organ system .
it is characterized by the accumulation of t lymphocytes and mononuclear phagocytes with the formation of noncaseating epithelioid granulomas in affected organs .
the trigger for this t cell and macrophage interaction is still uncertain , although bacterial , viral , and environmental antigens have all been studied .
recent literatures renewed the interest in mycobacteria as a causative agent in sarcoidosis tissue [ 2 , 3 ] . here
we present a case of presumed ocular sarcoidosis diagnosed by ocular manifestation and treatment course , who developed tuberculous lymphadenopathy 6  years later without recurrence of ocular inflammation .
a 35-year - old female was referred to our department with severe visual impairment for months .
she was quite healthy until 1  year ago when she began to suffer recurrent episodes of uveitis with mutton fat keratic precipitates ( kps ) in both eyes . on presentation ,
ocular examination showed mild anterior uveitis with mutton fat kps and dense vitreous hemorrhage in both eyes .
systemic workup including general physical examination , complete blood counting , differential classification , blood biochemical tests , rheumatic factor , antinuclear antibody , human immunodeficiency virus , venereal disease research laboratory test , anticardiolipin antibody , and chest radiography were within normal ranges . due to persistent vitreous hemorrhage and disabled vision ,
pars plana vitrectomy was performed in the left eye and then the right eye 2  months later .
sign of peripheral vasculitis with nodular choroid infiltration was noted during operation in both eyes .
gallium-67 scans showed panda sign of increased uptake in lacrimal glands and lambda sign of lymph nodes in the mediastinum ( fig .  1 ) .
chest computed tomography ( ct ) showed a small ground glass opacity nodule in the subpleural space of the right lower lobe , more in favor of inflammatory process .
based on these findings , ocular sarcoidosis was impressed and systemic and topical steroids administered in a tapering dose over 6  months .
unfortunately , painless enlargement of lymph node at her right neck was noted 6  years later .
lymph node biopsy showed granuloma with caseous necrosis , langhans giant cell , as well as acid - fast bacilli ( fig .  2 ) .
three combined antituberculosis medications ( rifampin , isoniazid , and pyrazinamide ) were given for 6  months .
the eyes remained silent except cataract progression and glaucoma under two medications during this period ( fig . 
1gallium-67 scans showed panda sign of increased uptake in lacrimal glands and lambda sign of lymph nodes in the mediastinumfig . 
2pathological finding from lymph node biopsy showed granuloma with caseous necrosis ( hematoxylin and eosin , 40 ) ( a ) , langhans giant cell ( hematoxylin and eosin , 400 ) ( b ) , as well as acid - fast bacilli ( kinyoun 's crystal fuchsin acid - fast stain , 1,000 ) ( c)fig . 
3postoperative color fundus picture of both eyes showed sheathing vessels and scattered laser scars at the inferior retina . a right eye .
b left eye gallium-67 scans showed panda sign of increased uptake in lacrimal glands and lambda sign of lymph nodes in the mediastinum pathological finding from lymph node biopsy showed granuloma with caseous necrosis ( hematoxylin and eosin , 40 ) ( a ) , langhans giant cell ( hematoxylin and eosin , 400 ) ( b ) , as well as acid - fast bacilli ( kinyoun 's crystal fuchsin acid - fast stain , 1,000 ) ( c ) postoperative color fundus picture of both eyes showed sheathing vessels and scattered laser scars at the inferior retina . a right eye .
the gold standard for diagnosis of sarcoidosis is histopathologic examination . considering the fact that ocular sarcoidosis may occur in the absence of apparent systemic involvement , and the fact that biopsy is usually reluctantly accepted by uveitis patients , the international workshop on ocular sarcoidosis ( iwos ) established an international criteria for the diagnosis of ocular sarcoidosis .
although there was no pathologic proof of sarcoidosis in our case , her ocular manifestations met at least five of the iwos criteria . though the lacrimal gland uptake of gallium ( panda sign ) is not a specific sign for sarcoidosis , her simultaneous presence of lambda and panda sign on ga-67 scans gave some support to sarcoidosis .
as guided , other granulomatous diseases , including tuberculosis , foreign body reaction , bacterial and viral infections , should be excluded before the diagnosis of sarcoidosis .
other laboratory and image study ruled out the other possible etiologies . besides , the ocular inflammation subsided after pars plana vitrectomy and systemic corticosteroid .
there was no recurrence of inflammation even at the time of tuberculous lymphadenopathy . presumed ocular sarcoidosis was impressed based on the ocular manifestations and treatment course .
we could not make any conclusion whether ocular sarcoidosis and tb lymphadenopathy in this patient is just coincident or in real association with each other . despite the increasing understanding of the immune responses behind the formation and maintenance of the granulomatous process in sarcoidosis
mycobacteria have been implicated as a cause of sarcoidosis , although the demonstration of mycobacterial dna was inconsistent in different reports [ 6 , 7 ] .
recent studies by detecting mycobacterium tuberculosis catalase  peroxidase have renewed interest in mycobacteria as a causative agent in sarcoidosis [ 2 , 3 ] . in our case , tb was ruled initially due to negative results of chest x - ray , aqueous tb culture , and pcr .
tuberculin skin test was not done as our cdc did not identify the significance of ppd in adult who received routine bacille calmette  guerin vaccination .
the ocular inflammation revolved after systemic steroid , and remained silent even at the presence of tb lymphadenopathy .
our speculation is that the presumed ocular sarcoidosis might be triggered by tb antigen in extraocular infection , which reactivated and presented as tb lymphadenopathy 6  years later .
tb could occur coincidently or in association with sarcoidosis , continued follow - up is important for patients with ocular sarcoidosis , even in silent case .
 tuberculosis and sarcoidosis share similarity in histopathologic findings and clinically occur in association with each other occasionally . 
 tuberculosis should always be ruled out before the diagnosis of sarcoidosis . 
 but , the diagnosis is often complicated , especially in extrapulmonary cases . here 
 we present a case of bilateral vitreous hemorrhage with uveitis . 
 ocular sarcoidosis was initially diagnosed based on the characteristic ocular findings , negative results on chest radiography , tuberculosis culture , and polymerase chain reaction of aqueous , as well as simultaneous presence of panda and lambda sign on gallium-67 scans . 
 the ocular condition improved after pars plana vitrectomy and systemic steroid therapy . 
 however , tb lymphadenopathy but no recurrent ocular inflammation was found 6  years later . 
 the patient received anti - tb treatment for 6  months thereafter . 
 the eyes remained silent except cataract progression and glaucoma under two medications during this period . in conclusion , tb could occur coincidently or in association with sarcoidosis , continued follow - up is important for patients with ocular sarcoidosis . 