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 . The consensus identified seven clinical signs suggesting 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. TB culture and PCR for aqueous were negative. 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, its etiology remained elusive. 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.