Consider masquerade syndromes when a differential diagnosis appears to indicate idiopathic uveitis

October 1, 2008

When making a differential diagnosis of idiopathic uveitis, remember that several malignant and non-malignant syndromes can masquerade as the condition. Making the correct diagnosis early allows prompt institution of appropriate therapy and avoids unnecessary treatment.

Key Points

Hong Kong-Masquerade syndromes-underlying disorders that present with signs and symptoms that appear to indicate idiopathic uveitis-are among the most challenging cases that present themselves to ophthalmologists, said Scott Whitcup, MD, at the World Ophthalmology Congress.

Correctly diagnosing masquerade syndromes is important.

Despite new diagnostic tests that can help in some conditions, a detailed clinical history and thorough clinical examination remain the keys to success, according to Dr. Whitcup, a member of the clinical faculty at the Jules Stein Eye Institute, University of California, Los Angeles, and executive vice president and head of research and development, Allergan.

"You need to handle the vitreous or cerebrospinal malignant specimens promptly," Dr. Whitcup said. "Malignant cells can die after about 20 to 30 minutes, so you really want it processed immediately. If you wait until the surgery is over, and the specimens are hours old, or, worse, sent the next day, you'll miss the diagnosis more often than you'll make it."

Persistence in diagnosing

An experienced cytopathologist also is important, because the diagnosis of intraocular lymphoma often is based on the presence of a handful of malignant cells, Dr. Whitcup said. Persistence also is critical because initial specimens can be negative for lymphoma in up to 30% of patients in whom the disease ultimately is diagnosed.

Cytokine profiles in the vitreous also can help. If the level of interleukin-10 is greater than the inflammatory level of the inflammatory cytokine interleukin-6, there is a high suspicion of lymphoma.

Ophthalmologists also should be aware of metastatic disease to the eye, which can masquerade as inflammatory or infectious uveitis, Dr. Whitcup said.

Several non-malignant conditions-trauma, choroidal osteoma, asteroid hyalosis, pigment dispersion syndrome-can masquerade as uveitis, he said, and retinal disorders such as retinal detachment, retinoschisis, myopic degeneration, and lipemia retinalis also can masquerade as ocular inflammatory disease. Retinal degenerations such as retinitis pigmentosa can masquerade as uveitis, Dr. Whitcup added. In many of these patients, an electroretinogram can help with the diagnosis, he said. Patients with retinitis pigmentosa have a profoundly diminished electroretinogram, whereas patients with uveitis typically have less affected recordings, Dr. Whitcup noted.

According to Dr. Whitcup, a good rule-of-thumb clue to patients who present with a masquerade syndrome is unresponsiveness to anti-inflammatory therapy. Most forms of uveitis will respond-at least partially-to corticosteroids or immunosuppressive agents. If the disease is only minimally responsive or is nonresponsive to therapy, a masquerade syndrome should be strongly considered, he said.

"Consider masquerade syndrome in your differential diagnosis of idiopathic uveitis," he concluded. "Always ask if it could be a masquerade. If you think about it, you catch it. And that allows prompt institution of appropriate therapy and avoids unnecessary treatment."