Nodular Granulomatous Episcleritis

Visualizing Nodular Granulomatous Episcleritis

1 / 5

FIGURE 1 Classic form of NGE affecting the dorsolateral limbus. Localized episcleroconjunctivitis and keratitis with conjunctival hyperemia, corneal neovascularization, and corneal edema can be seen.

1 / 5

FIGURE 1 Classic form of NGE affecting the dorsolateral limbus. Localized episcleroconjunctivitis and keratitis with conjunctival hyperemia, corneal neovascularization, and corneal edema can be seen.

Understanding Nodular Granulomatous Episcleritis

Nodular granulomatous episcleritis (NGE) is a proliferative form of episcleritis characterized by localized inflammation of the episcleral tissue. This condition is also referred to as scleritis, episcleroconjunctivitis, and episclerokeratoconjunctivitis because of the proximity to adjacent ocular structures and the ability to affect various surrounding tissues, including the conjunctiva, orbital tissue, cornea, and uveal tract. Secondary complications may include chorioretinitis, retinal detachment, keratitis, or orbital cellulitis.

The pathophysiology of NGE is not fully understood, but the response to immunomodulatory treatments suggests an immune-mediated basis. NGE is more prevalent in collies, cocker spaniels, and Shetland sheepdogs but can occur in any breed. Collies often exhibit bilateral involvement and a higher recurrence rate following treatment. Although bilateral involvement is more frequent in collies, presentation is usually asymmetrical.

NGE typically appears as multiple or singular raised, tan-colored masses at the limbus, often infiltrating adjacent corneal stroma. Common features include nictitating membrane involvement, tan to red subconjunctival masses, and dorsolateral limbal thickening. Corneal involvement may manifest as stromal invasion, crystalline opacities, and edema. Although bilateral cases are more frequent in collies, presentation is usually asymmetrical.

Diagnosing & Treating Nodular Granulomatous Episcleritis

Diagnosis is primarily based on physical examination findings, patient factors as described above, and response to treatment. Histopathology is rarely performed but is the definitive diagnostic tool and helps differentiate NGE from neoplastic conditions (eg, squamous cell carcinoma, limbal melanocytoma, lymphoma). Histopathologic findings typically show chronic granulomatous inflammation with predominant histiocytes, lymphocytes, and plasma cells. The presence of T cells aligns with the response to immunosuppressive treatments (eg, azathioprine, cyclosporine).

Treatment includes a combination of topical corticosteroids, immunomodulatory agents, and surgical intervention (in some cases). Topical cyclosporine or tacrolimus in conjunction with corticosteroids can induce clinical remission. Corticosteroids should be tapered and discontinued once control is achieved. Cyclosporine and tacrolimus should be maintained at the lowest effective dose to prevent recurrence. Oral treatments (eg, azathioprine) may be required to achieve control, but careful monitoring is needed due to potential toxicities (eg, GI distress, hepatotoxicity, myelosuppression). Oral cyclosporine may be used for refractory cases but is contraindicated in patients with kidney or liver disease. Routine blood work is needed to ensure safety prior to beginning oral treatment for NGE. Treatment escalation should not compromise the patient’s overall health.

Prognosis is generally favorable, with most patients responding well to topical therapy and able to achieve clinical remission; however, recurrence is possible, and treatment may be lifelong in some patients. Recurrence rates have not been reported. Long-term management should focus on achieving disease control with the lowest effective dose.