Seek and ye shall find the cause!

A 25-year-old Asian Indian female presented with recurrent episodes of choroiditis in her left eye for the past 5 years. She was treated with oral steroids and immunosuppressive therapy (oral methotrexate (10–15 mg/m2/week)) elsewhere but continued to have recurrent episodes of inflammation. At presentation, her visual acuity was 6/6 in the right eye (OD) and 1/60 in the left eye (OS). Fundus examination of OS showed 1+ vitritis with a large subretinal yellowish lesion (choroidal granuloma) at the macula (arrow) [Fig. 1a]. On fundus fluorescein angiography (ultra-widefield silverstone [Optos PLC Edinburgh]), the corresponding choroidal lesion was hypofluorescent with some late peripheral hyperfluorescence (double arrow) [Fig. 1b]. The lesion was hypofluorescent in both the early and late phases of indocyanine green angiography [Fig. 1c]. Swept-source optical coherence tomography line scan passing through the lesion showed a dome-shaped elevation of the choroid (asterisk) with perilesional fluid (arrowhead) and overlying vitreous cells [Fig. 1d]. Laboratory workup, including Mantoux, Interferon Gamma Release Assay (IGRA), Contrast-enhanced Computed Tomography (CECT) Chest, and serology for syphilis and Human Immunodeficiency Virus, was negative.

Figure 1.

The ultra-widefield fundus photograph (Optos PLC Edinburgh) of the left eye shows a large subretinal yellowish lesion (choroidal granuloma) at the macula (arrow). (a) On corresponding fundus fluorescein angiography, the lesion is hypo-fluorescent in the early phase with some late peripheral hyper-fluorescence (double arrow). (b) The lesion appears hypo-fluorescent in both the early and late phases of indocyanine green angiography. (c) Swept-source optical coherence tomography line scan passing through the lesion shows a dome-shaped choroidal elevation (asterisk) with perilesional fluid (arrowhead). (d)

What will you do next?

1. Continue treatment with oral steroids and immunosuppressive therapy

2. Plan diagnostic vitrectomy

3. Treat with intravitreal clindamycin and dexamethasone

4. Advise 18-fluorodeoxyglucose positron emission tomography (FDG-PET) to identify occult foci of inflammation/infection and confirm the primary pathology

Findings and Management

An18-FDG-PET scan was performed. A focal FDG uptake was found in the left parotid gland (blue arrow) [Fig. 2]. Retrospective history revealed a painless, on-and-off swelling in the left preauricular region for the past two years. Imaging guided fine needle aspiration cytology (FNAC) was performed. FNAC showed lymphoid cells which are seen in association with the clusters and scattered in the background along with degenerated cells and macrophages suggestive of granulomatous inflammation consistent with tuberculosis (TB). Diagnosis of choroidal TB granuloma was made, and the patient was started on anti-tubercular therapy (Isoniazid 5mg/kg/d, Rifampicin 10mg/kg/d, Pyrazinamide 25mg/kg/d, and Ethambutol 15mg/kg/d) along with oral steroids (1mg/kg/d). Additionally, intra-vitreal dexamethasone (0.7 mg) implant (Ozurdex®) was also given for early resolution of inflammation. The patient responded to treatment with the resolution of choroidal granuloma. Visual acuity, however, remained 1/60 due to a macular scar.

Figure 2.

18-Fluoro-deoxyglucose Positron Emission Tomography (FDG-PET) shows a focal FDG uptake along inferior end of left parotid gland (arrow)

Diagnosis

Parotid tuberculosis with tubercular choroiditis

Correct answer

D. Advise 18-fluorodeoxyglucose positron emission tomography (FDG-PET) to identify occult foci of inflammation/infection and confirm the primary pathology

Discussion

Tubercular choroiditis is a manifestation of ocular tuberculosis predominantly affecting the choroid, often associated with systemic tuberculosis.[1] It presents as serpiginous like choroiditis or tuberculomas—multifocal or solitary granulomatous lesions. Diagnosis often relies on imaging modalities such as fluorescein angiography and indocyanine green angiography, which reveal characteristic hypofluorescent lesions while immunological (Mantoux/IGRA) and radiological tests (CXR/CECT Chest) are helpful in confirming the etiology.[1] Collaborative Ocular Tuberculosis Study Consensus Guidelines recommend initiating anti-tubercular therapy in tubercular choroiditis in the presence of positive results for any one of the positive immunologic tests (Mantoux/IGRA) along with radiologic features suggestive of tuberculosis.[2] However, in rare cases, the conventional investigations may not be directed toward the diagnosis. In the absence of an obvious foci of infection, an 18-FDG-PET scan may prove to be a useful modality to pick up occult/subclinical lesions. In a large series of 27 patients with presumed ocular tuberculosis, Mehta reported positive PET/CT findings in 14/27 (51.85%) patients with otherwise absent clinical evidence of systemic tuberculosis.[3] Metabolically active lymphadenopathy was the most common finding. In another report by Doycheva et al.,[4] 18-F FDG-PET/CT was found to be useful in identifying the lesions appropriate for biopsy and help to establish the diagnosis in patients with presumed tuberculosis-induced intraocular inflammation. However, none of the patients showed involvement of the parotid gland in either of these reports.

Besides cervical lymph nodes, tuberculous involvement of the head and neck is unusual. Parotid tuberculosis is a rare form of extrapulmonary tuberculosis, often mistaken for neoplasms due to its nonspecific presentation as a parotid mass or abscess. The pathogenesis involves hematogenous or lymphatic spread from a primary focus or direct extension via the ductal system.[5] Diagnosis typically requires histological confirmation of granulomatous inflammation and microbiological evidence of Mycobacterium tuberculosis. Imaging modalities like CT or MRI can identify lesions but lack specificity. FNAC is often diagnostic. Standard anti-tubercular therapy is highly effective, with surgical intervention rarely needed.[5]

Conflicts of interest:

There are no conflicts of interest.

Funding Statement

Nil.