Multifocal Choroiditis and Panuveitis
MCP is a condition characterized by intraocular inflammation and multifocal choroidal lesions occurring in the absence of any known ocular or systemic disease. The disease is typically bilateral and seems to have a predilection for females in the second to sixth decades of life, with a median age of 28 to 33 years. Patients report blurred vision, floaters, photopsias, and scotomata including an enlarged blind spot.
Examination during the active stage reveals inflammation in the anterior chamber and vitreous, an important finding distinguishing MCP from the presumed ocular histoplasmosis syndrome (POHS). The choroidal lesions may range from approximately 50 to 350 μm in size and may be located in the posterior or peripheral fundus, concentrated in the macula or forming peripheral linear streaks. Active lesions appear as yellowish-white choroidal infiltrates and may be associated with neurosensory retinal detachments, vascular sheathing, disc edema, and cystoid macular edema. Inactive lesions appear as variably pigmented, punched-out areas of chorioretinal atrophy. Peripapillary scarring and extensive subretinal fibrosis are also common findings (Figure 2).
On fluorescein angiography active lesions may show early hypofluorescence with late hyperfluorescence. Cystoid macular edema is seen in 14% to 41% of affected eyes. ICG angiography shows more hypofluorescent lesions than observed by ophthalmoscopy. Visual field testing may show an enlarged blind spot and defects corresponding with the extent of multifocal lesions. Even in the absence of active disease the ERG may show progressive deterioration. There is no diagnostic laboratory test for MCP. The diagnosis is one of exclusion; therefore, tests are needed to rule out other causes of uveitis and systemic diseases in the differential diagnosis, such as birdshot retinochoroidopathy (HLA-A29), sarcoidosis (chest xray, ACE), Vogt-Koyanagi-Harada syndrome (VKH, consider lumbar puncture and audiology), syphilis (RPR or VDRL and MHA-TP or FTA-ABS), and tuberculosis (tuberculin skin test, chest x-ray).
The prognosis for MCP is guarded. The active disease course may be short, with few lesions, or chronic, with recurrent exacerbations of intraocular inflammation and the development of numerous lesions, progressive scarring, and retinal degeneration. Cystoid macular edema, subretinal fibrosis, and choroidal neovascularization are common causes of visual loss. Treatment relies on the use of corticosteroids (oral or periocular) with the use of other immunosuppressive agents (cyclosporine, azathioprine, methotrexate, chlorambucil, cyclophosphamide) as needed depending on the severity of the disease. Management of choroidal neovascularization, a poor prognostic sign, can be difficult as the best treatment is yet to be determined and spontaneous regression may occur. The current treatment options include periocular, intraocular, or oral corticosteroids; laser photocoagulation; photodynamic therapy; and, most recently, anti-VEGF therapy. Submacular surgical removal of choroidal neovascular membranes may be considered in some patients. The cause of MCP is unknown. Patients with MCP have been reported to develop transient white retinal lesions similar to those seen in MEWDS. A vitrectomy specimen from a patient with active disease revealed large numbers of T-cells and histopathologic examination of a chorioretinal biopsy and a postmortem eye showed populations of predominantly B-cells and T-cells in the choroid, respectively, supporting the notion of an immune-mediated disease.