Tubercular chorioretinitis mimicking sarcoidosis in a patient with celiac disease and erythema nodosum: A case report

Abstract

BACKGROUND

Tuberculosis remains an important cause of uveitis in tuberculosis-endemic regions and can closely resemble other granulomatous disorders, such as sarcoidosis, especially in the presence of erythema nodosum. The diagnosis is even more challenging in the presence of an underlying autoimmune condition such as celiac disease.

CASE SUMMARY

We report a case of a middle-aged female, a known case of celiac disease and recurrent severe anaemia presenting with progressive, recurring episodes of bilateral diminished vision, ocular pain, photophobia, and floaters over a period of 1.5 years. Ocular examination revealed bilateral vitritis with chorioretinal lesions consistent with posterior uveitis, more severe in the left eye. Initially, the presence of erythema nodosum and systemic symptoms raised the possibility of sarcoidosis; however, an extensive systemic workup ruled it out. A positive QuantiFERON-TB Gold test, past history of treated cervical lymph node tuberculosis, relevant family history, and favourable clinical response to antitubercular therapy favoured the diagnosis of presumed tubercular chorioretinitis. The treatment included antitubercular therapy, systemic corticosteroids, and posterior subtenon triamcinolone injections which led to clinical improvement; however, there was a recurrence of the disease after completing treatment, which required initiation of systemic azathioprine.

CONCLUSION

This case highlights the need for a high index of suspicion for ocular tuberculosis in patients presenting with posterior uveitis and erythema nodosum. Detailed assessment and exclusion of close differentials are essential so that timely diagnosis and optimum management can be done, especially in endemic areas.

Key Words: Tubercular uveitis; Erythema nodosum; Sarcoidosis; Celiac disease; Panuveitis; Case report

Core Tip: This case underscores the diagnostic challenges posed by posterior uveitis in patients with underlying autoimmune conditions such as celiac disease and recurrent anemia, especially in tuberculosis-endemic regions. The presence of erythema nodosum and systemic symptoms can mimic other granulomatous diseases like sarcoidosis, making timely and accurate diagnosis difficult. However, a comprehensive evaluation including immunological testing, history of tuberculosis, family history, and response to antitubercular therapy was pivotal in establishing presumed tubercular chorioretinitis as the diagnosis. The case highlights the importance of maintaining a high index of suspicion for ocular tuberculosis and the need for a multidisciplinary approach to management, utilizing antitubercular drugs, corticosteroids, and immunosuppressants when necessary, to achieve optimal clinical outcomes.

INTRODUCTION

Tuberculosis remains a prevalent cause of uveitis in endemic regions and is often described as a “great masquerader” because of the absence of pathognomonic clinical features and its ability to mimic other granulomatous inflammatory disorders[1]. Its ocular manifestations frequently overlap with those of sarcoidosis, particularly in the presence of systemic features such as erythema nodosum, leading to significant diagnostic challenges[1,2]. This overlap is especially problematic in tuberculosis-endemic populations, where a diagnosis of sarcoidosis is often made in patients who present with erythema nodosum.

Diagnostic complexity is further increased in patients with chronic autoimmune diseases like celiac disease, which seldom but does have a documented association with recurrent uveitis. The nonspecific autoimmune serological markers include positivity for antinuclear antibody (ANA) and thus can lead to diagnostic confusion with systemic inflammatory disorders such as systemic lupus erythematosus. Therefore, the need for careful clinical correlation and the judicious use of ancillary investigations becomes indispensable for establishing the correct etiology and guiding appropriate management.

CASE PRESENTATION

Chief complaints

A 34-year-old woman presented in 2025 with episodic, recurrent episodes of bilateral blurred vision, ocular pain, photophobia, and floaters for 1.5 years.

History of present illness

She has had these ocular complaints for the last 1.5 years. With biopsy-proven celiac disease diagnosed in the year 2021 and chronic anemia requiring multiple packed red blood cell transfusions.

History of past illness

She also had a history of a completed six-month course of antitubercular therapy for cervical lymph node tuberculosis in 2022.

Personal and family history

There was a family history of pulmonary tuberculosis in her brother. During recent ocular exacerbations, she reported generalized fatigue and reduced appetite.

Physical examination

Systemic examination revealed a 3-cm tender, erythematous-to-violaceous subcutaneous nodule over the left shin, clinically consistent with erythema nodosum.

In the right eye, best-corrected visual acuity was 6/9, the anterior chamber was quiet, and fundus examination showed grade I vitritis with two to three hypopigmented healed chorioretinal patches in the inferotemporal quadrant of the posterior pole. In the left eye, best-corrected visual acuity was 6/24. There was diffuse iris atrophy with a festooned pupil secondary to broad-based posterior synechiae at the 2 o’clock, 6 o’clock, and 11 o’clock positions, as well as a complicated cataract with polychromatic luster. Fundus details in the left eye were obscured by grade III vitritis and a non-dilating pupil, although the optic disc appeared hyperemic (Figure 1).

Figure 1 Clinical ocular manifestations of chronic panuveitis. A: Slit-lamp photograph of the left eye demonstrating diffuse, flat, pigmented keratic precipitates on the corneal endothelium; B: Slit-lamp photograph of the left eye showing a festooned pupil due to broad-based posterior synechiae with a complicated cataract; C: Color fundus photograph of the right eye showing grade I vitritis with healed, hypopigmented chorioretinal patches; D: Color fundus photograph of the left eye showing dense vitritis with obscured fundus details.

Laboratory examinations

Laboratory evaluation revealed a positive interferon-gamma release assay, pancytopenia, a negative ANA profile, and the absence of anti-dsDNA antibodies, and normal complement levels suggested that these findings were secondary to chronic inflammation rather than systemic lupus erythematosus.

Imaging examinations

Fundus fluorescein angiography (FFA) of the right eye revealed segmental perivascular leakage in a few areas, indicating active vasculitis in the mid-peripheral retina without any signs of leakage in the macular area or capillary dropout areas. FFA photos of the left eye could not be obtained. The high-resolution computed tomography scan of the chest showed multiple subcentimetric paratracheal and subcarinal nodes with calcification (Figure 2).

Figure 2 Systemic markers and multimodal imaging. A: Clinical photograph of the left shin showing a tender erythematous subcutaneous nodule consistent with erythema nodosum; B: Optical coherence tomography of both eyes showing hyperreflective echoes in the vitreous cavity consistent with vitritis; C: Fundus fluorescein angiography of the right eye showing segmental perivascular leakage in the mid-peripheral retina suggestive of retinal vasculitis.

MULTIDISCIPLINARY EXPERT CONSULTATION

The clinical differential diagnoses were sarcoidosis, systemic lupus erythematosus, and ocular tuberculosis. Blood tests for angiotensin-converting enzyme and calcium levels were reported to be within the normal range. Also, the lack of hilar adenopathy did not support the presence of sarcoidosis.

FINAL DIAGNOSIS

A positive interferon-gamma release assay, along with supportive clinical history and therapeutic response, favored a diagnosis of tubercular chorioretinitis.

TREATMENT

The patient was re-initiated on a four-drug antitubercular regimen consisting of rifampicin, isoniazid, pyrazinamide, and ethambutol, along with systemic corticosteroids. Posterior sub tenon triamcinolone injections were administered, first in the left eye followed by the right. At the 2-week follow-up, the patient reported improvement in symptoms, and visual acuity in the right eye improved to 6/6 and the left eye to 6/9. However, after 2 weeks of completion of systemic steroid therapy, there was again a recurrence of vitritis and hence systemic azathioprine was started as a steroid-sparing immunosuppressive agent for 3 months.

OUTCOME AND FOLLOW-UP

The patient’s signs and symptoms improved after initiating the treatment, and she’s been under constant follow-up for the last 1 year with no recurrence.

DISCUSSION

This case highlights just how closely sarcoidosis and tuberculosis can mimic each other, particularly in regions where tuberculosis is common. Symptoms such as erythema nodosum can sometimes lead doctors to initially suspect sarcoidosis[1]. According to Agrawal et al[1] in areas with a high prevalence of tuberculosis, it can be difficult to tell the two apart, because even though they sit at different points on a disease spectrum, they share many similar clinical, radiological, and immunological characteristics[1]. Erythema nodosum is not specific to any single disease and has been observed in a wide range of inflammatory and infectious conditions, including tuberculosis, even though it is traditionally associated with sarcoidosis[2]. Its presence should not be taken as definitive evidence of sarcoidosis, but rather as a signal to carefully investigate the possibility of tuberculosis.

In regions where tuberculosis is endemic, the markers usually relied upon to support a diagnosis of sarcoidosis may not always be reliable. Sarcoidosis becomes less likely when there is no enlargement of the lymph nodes near the lungs and when calcium levels and serum angiotensin-converting enzyme are normal[3]. A multicentered study conducted in a high tuberculosis-burden setting showed that depending solely on these markers can be misleading and highlighted the importance of excluding tuberculosis before confirming a diagnosis of ocular sarcoidosis[3]. In this case, there were no systemic or imaging findings to support sarcoidosis. Other differential diagnosis of posterior uveitis were also systematically considered. Behçet disease was unlikely due to the absence of recurrent oral or genital ulcers and lack of occlusive retinal vasculitis. Infectious uveitis, including toxoplasmosis and viral etiologies, was excluded based on lesion morphology, absence of focal necrotizing retinitis, and lack of characteristic clinical features. Idiopathic posterior uveitis was excluded due to the presence of systemic findings such as erythema nodosum, a positive interferon-gamma release assay, and a history suggestive of tuberculosis exposure, which made this diagnosis less probable.

The situation can be further complicated when autoimmune conditions, such as celiac disease, are also present. Individuals with autoimmune disorders may show nonspecific blood markers, like positive antinuclear antibodies, and uveitis has been reported as an extraintestinal manifestation of celiac disease[4]. In the absence of other clinical or immunological signs, isolated ANA positivity is common in the general population and does not indicate systemic lupus erythematosus[5]. International guidelines emphasize that ANA results should always be interpreted with care and in the context of the patient’s overall clinical picture to avoid overdiagnosis[5]. In this patient, celiac disease was therefore considered as a potential contributor to immune dysregulation rather than a primary etiological factor for posterior uveitis.

The diagnosis in this case was classified as presumed ocular tuberculosis, because of the diagnostic limitations associated with ocular involvement. Microbiological confirmation is usually negative due to the paucibacillary nature of intraocular disease. Tuberculous uveitis is primarily diagnosed based on characteristic eye findings. Both healed and active choroidal lesions appear as pigmented, atrophic patches along the retinal vessels, which are well-established indicators of ocular tuberculosis[6]. In patients with posterior uveitis or chorioretinitis, evidence of prior tuberculosis exposure, such as a positive interferon-gamma release assay, adds strong support to the diagnosis[7].

Current guidelines for diagnosing ocular tuberculosis stress the importance of combining clinical signs, immunological tests, and imaging findings, even if the lungs appear normal[8]. Ocular tuberculosis can be difficult to manage because relapses may happen despite following normal anti-tuberculosis medication. Studies indicate that the generally prescribed six-month course may not completely suffice when there is ocular involvement[9]. Agrawal et al[1] suggested that a longer course of therapy leads to better results and requires individualization based upon the severity of the disease and susceptibility to treatment[9]. In the present case, azathioprine was initiated after excluding active systemic tuberculosis and with careful monitoring, balancing the risk of reactivation against the need to control intraocular inflammation. Relapses were found to continue despite initial signs of a cure; hence, close monitoring as well as proper usage of immunosuppressive therapy may be required[10].

CONCLUSION

This case underscores the intricate diagnostic challenges encountered when distinguishing between sarcoidosis and tuberculosis, particularly in regions with a high prevalence of tuberculosis. Overlapping clinical features, such as erythema nodosum and similar radiological and immunological findings, often complicate the clinical picture and may lead to diagnostic uncertainty. The coexistence of autoimmune conditions like celiac disease adds an additional layer of complexity, as nonspecific serological markers such as ANA can be misleading and should not be interpreted in isolation. It is therefore essential to adopt a comprehensive diagnostic approach, integrating clinical, radiological, and laboratory findings, while maintaining a high index of suspicion for tuberculosis in endemic areas. Furthermore, the management of ocular tuberculosis requires careful consideration, as relapses are possible and may necessitate prolonged and individualized therapy. Ultimately, multidisciplinary collaboration and vigilant follow-up are crucial for accurate diagnosis and optimal patient outcomes in such complex cases.