Healing patterns of choroidal tubercles after antitubercular therapy

A 28-year-old female patient was referred to us for evaluation. She had a history of high-grade fever and severe headache in the preceding 2 months and had undergone a systemic evaluation during the preceding week. She was anemic (hemoglobin 10.3 g%) but had normal total and differential white cell counts. Her erythrocyte sedimentation rate (ESR) was 84 mm/h (normal <20 mm/h). Investigations for renal and liver functions were normal. Her serum angiotensin-converting enzyme (ACE) was within normal limits. Her mantoux test was strongly positive at 23 × 25 mm. Magnetic resonance imaging (MRI) of the brain showed multiple ring-shaped lesions in the cerebral and cerebellar areas, with perilesional edema and contrast enhancement. Computed tomography (CT) of the chest revealed multiple discrete nodular opacities in the lung parenchyma bilaterally and enlargement of the mediastinal nodes. A diagnosis of disseminated tuberculosis had been made, and she had been started on a four-drug antitubercular drug regimen (initial 2 months of ethambutol [15 mg/kg body weight], rifampicin [10 mg/kg], isoniazid [5 mg/kg] and pyrazinamide [25 mg/kg] followed by 7 months of rifampicin and isoniazid).

On examination, her visual acuity was 6/6 bilaterally. A slit lamp examination was normal in either eye. Dilated fundus examination was normal in the right eye and showed two white to yellow 1/3 to 1/2 disc diameter sized choroidal lesions (in the nasal quadrant and temporal to the macula) consistent with tubercles. She underwent fundus photography and OCT (Stratus, Carl Zeiss Meditec, Oberkochen, Germany). We used the line scan program (normalize + align analysis) on a monthly basis for four visits, until clinical healing of the tubercles was achieved.

The tubercle was approximately 1/2 DD in size and consisted of a central white-yellow core, consistent with choroiditis, with a faint hyperpigmentation surrounding it. There was a surrounding diffuse rim of inflammation (Fig. 1a), consistent with a surrounding retinal inflammation. By the second month, the hyperpigmented rim was more prominent, and the outer edges of both the central core and the outer rim were more distinct (Fig. 1b). By the third month, the outer rim had largely faded with concurrent scar formation in the core (Fig. 1c). This scar (referred to as a “parchment” scar in earlier publications) was complete by the fourth month (Fig. 1d). At the initial visit, OCT analysis revealed a raised RPE-choriocapillaris complex consistent with a raised choroidal lesion at the initial visit. The overlying retina appeared normal (Fig. 2a). These findings persisted into the second month (Fig. 2b). At the third month, there was a marked reduction in the choroidal lesional height suggesting resolution (Fig. 2c). At the fourth month, there was a complete flattening of the choroidal lesion with a hyper reflectivity and “shadowing” of the area of the lesion. The overlying retina appeared slightly depressed, suggesting a dense contracted scar formation (Fig. 2d).