A rare form of eye cancer called adnexal lymphoma can hide behind the symptoms of common retinal diseases, potentially delaying diagnosis and treatment. One 72-year-old patient initially received treatment for episcleritis and was later misdiagnosed with birdshot chorioretinopathy before doctors finally identified the true culprit: a malignant lymphoma of the eye's outer tissues. The case underscores why retina specialists need to cast a wider diagnostic net when patients present with unusual eye inflammation and vision changes .

What Is Adnexal Lymphoma and Why Should You Care?

Adnexal lymphoma is a malignant disease of the immune system that develops in the tissues surrounding the eye, including the orbit, eyelids, conjunctiva, and lacrimal gland. Unlike aggressive brain lymphomas that spread rapidly, adnexal lymphomas are generally slower-growing but can still cause significant local damage and vision loss if left untreated. The disease arises from mucosal tissues and is most commonly diagnosed as extranodal marginal zone lymphoma on tissue biopsy, though follicular, large B-cell, and mantle cell variants also occur .

The challenge with adnexal lymphoma is that its symptoms closely mimic benign eye conditions. Patients often experience redness, difficulty seeing in bright light, and changes in color perception. These vague complaints can lead doctors down the wrong diagnostic path, resulting in months of ineffective treatment with steroids and other anti-inflammatory medications.

How Can Doctors Distinguish Adnexal Lymphoma From Other Retinal Diseases?

The key to catching adnexal lymphoma early lies in recognizing a distinctive physical sign and performing thorough imaging. In the case described, a retina specialist initially diagnosed birdshot chorioretinopathy based on fundus photography and angiography findings. However, when a uveitis specialist reviewed the patient's imaging and performed a careful clinical examination, they spotted a salmon-colored lesion on the conjunctiva. This "salmon patch" is a characteristic finding in adnexal lymphomas and should prompt immediate further investigation .

Once suspected, the diagnosis requires tissue confirmation. An incisional biopsy of the suspicious lesion can reveal the histopathologic findings consistent with lymphoma. In the case presented, biopsy confirmed extranodal marginal zone lymphoma, allowing doctors to pivot from steroid therapy to appropriate cancer treatment .

Steps to Ensure Proper Diagnosis of Eye Lesions

• Visual Inspection: Carefully examine the conjunctiva, eyelids, and orbit for any salmon-colored or unusual lesions, especially if a patient reports redness or vision changes without obvious inflammation.
• Advanced Imaging: Perform fundus photography, fluorescein angiography, and optical coherence tomography (OCT) to assess the retina and choroid. In adnexal lymphoma, the choroid may appear abnormally thick with a convex macular surface.
• Tissue Biopsy: If imaging findings are atypical or a suspicious lesion is present, obtain an incisional biopsy to confirm or rule out malignancy before starting long-term steroid therapy.
• Multidisciplinary Consultation: Involve retina specialists, uveitis specialists, and ocular oncologists in complex cases to ensure no diagnostic stone is left unturned.

What Happens After Diagnosis?

Once adnexal lymphoma is confirmed, treatment typically involves external beam radiotherapy. In the patient case, radiation therapy successfully resolved the disease. Follow-up OCT imaging showed dramatic improvement: the abnormally thickened choroid returned to normal thickness, and the convex macular surface returned to its normal concave shape, indicating restoration of retinal anatomy and function .

The prognosis for adnexal lymphomas is generally better than for aggressive CNS lymphomas, but early detection remains critical. Delayed diagnosis means prolonged vision loss and increased risk of permanent retinal damage. The patient in this case was fortunate that a careful clinical examination eventually led to the correct diagnosis, but many cases may be missed if doctors do not maintain a high index of suspicion.

Why Retina Specialists Need to Think Beyond Common Diagnoses

Lymphoma is rare in the eye, which is precisely why it is often overlooked. Early-career ophthalmology residents may recognize the salmon patch sign, but many practicing specialists may not immediately connect this finding to malignancy. The disease can present with findings that overlap with uveitis, chorioretinopathy, and other inflammatory conditions, making it easy to default to steroid therapy without considering alternative diagnoses .

Considerable confusion exists within ophthalmology regarding lymphomatous diseases, likely due to their rarity and diagnostic difficulty. However, the stakes are high: misdiagnosis delays appropriate treatment and allows the disease to progress unchecked. Retina specialists should recognize that the choroid is viewed by the immune system as contiguous with mucosal tissues, making it a potential site for lymphoma development even when the iris and ciliary body are spared .

The takeaway for patients is simple: if you experience persistent eye redness, vision changes, or difficulty seeing in bright light that does not respond to standard treatments, ask your eye doctor to consider less common diagnoses. Request a second opinion from a retina specialist or ocular oncologist if your symptoms persist. And for eye care professionals, remember that not every case of chorioretinopathy or uveitis is what it appears to be on first glance.

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