A 39-year-old woman with disseminated tuberculosis and bilateral solitary choroidal tubercles [Fig. 1a and b] was subjected to multimodal imaging including enhanced depth imaging spectral-domain optical coherence tomography (EDI-OCT), near-infrared reflectance (NIR), and fundus autofluorescence (FAF) imaging. FAF imaging revealed hyperautofluorescent lesion with central hypoautofluorescence [Fig. 1c and d]. NIR imaging revealed hyperreflective lesion with a hyporeflective halo [Fig. 2a and c]. EDI-OCT [Fig. 2b and d] showed lobulated hypo/isoreflective choroidal lesion with loss of vascular pattern and dome-shaped elevation of the overlying retina. Characteristic “increased transmission effect” was seen beneath the lesion. A small cap of subretinal fluid at the apex of lesion was noted in the right eye. Antituberculous therapy resulted in systemic improvement and regression of choroidal tubercles [Figs. 3 and 4a-i].
Characterization of choroidal lesions has evolved with the advent of modalities that enable imaging of the choroid and sclera (EDI-OCT); melanin, collagen, or fibrin (NIR imaging), and fluorophores (FAF). EDI-OCT enabled morphological evaluation of lesions, precise localization and measurement, and monitoring during treatment. NIR imaging which provided high-resolution enface images of subretinal pathologies demonstrated choroidal tubercles as hyperreflective due to unmasking of scleral collagen caused by defective choroidal pigmentation. There is only a single report of FAF imaging of choroidal tubercle. Acute lesion was hyperautofluorescent due to increased lipofuscin in the diseased retinal pigment epithelium (RPE), and the central hypoautofluorescence could be due to absent RPE, sparse lipofuscin, or secondary retinal infiltration. Posttreatment lesion may become iso/hypoautofluorescent. This FAF pattern is distinct from the heterogeneous appearance of choroidal metastasis, amelanotic melanomas, or nevus which results from lipofuscin, fluid, or RPE atrophy. Thus, combined imaging helped to evaluate and monitor the chorioretinal pathology noninvasively in our patient with choroidal tubercles. Immunohistochemical studies of excised tuberculous pulmonary granulomas have shown that increased accumulation of lipid-rich caseum in the granulomas due to dysregulation in the host lipid metabolism signifies the progression of latent disease to active infection. Further studies with FAF might help to detect similar changes in choroidal granulomas in vivo and thus obtain valuable insights into our understanding of ocular tuberculosis.
Distinct FAF features (hyperautofluorescent with central hypoautofluorescence) may help diagnose choroidal tubercles and differentiate from other simulating clinical conditions.
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The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
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