Gallium scintigraphy in the investigation of retinal inflammatory vasculopathy

Abstract

Editor, Retinal inflammatory vasculopathy can be a sight-threatening manifestation of systemic inflammatory disease. Despite extensive investigation, the etiology of inflammatory retinal vasculopathy in many cases remains elusive. In the absence of a medical history suggestive of systemic disease, the utility of systemic evaluation can have a low diagnostic yield.(George et al., 1996). The use of whole-body gallium-67 scintigraphy, however, may shed light on the etiology of inflammatory retinal vasculopathy in such cases. We report the findings of four consecutive patients who presented over a two year period with retinal inflammatory vasculopathy without any signs or symptoms of systemic disease. Three patients were African-American and one was Caucasian, with an age range of 42–59 years. All patients exhibited inflammatory changes of the retina including periphlebitis, peripheral nonperfusion, aneurysmal changes, macular edema, and neovascularization. Anterior uveitis was absent in all cases, but unilateral mild vitritis associated with papillitis was seen in one patient. Serum angiotensin converting enzyme (ACE) levels were normal in all patients. Radiological examinations to detect pulmonary disease including chest x-ray, high-resolution chest CT, and whole-body gallium-67 scanning were negative. All patients tested negative for anti-Ro and anti-La antibodies, which excluded the diagnosis of Sjogren syndrome. Syphilis testing (FTA-ABS) was also negative. Three patients had negative reaction to purified protein derivative (PPD) skin testing, while one patient had a remote history of a positive PPD test that had been treated with isoniazid (INH). Investigations for hypercoagulability, sickle cell disease, and connective tissue disease were negative. Gallium-67 scintigraphy, however, showed in all 4 cases characteristic bilateral increased uptake in the lacrimal glands that in 2 out of 4 cases was associated with concurrent parotid gland involvement. The retinal vascular findings in our series of patients have been previously described in patients with sarcoidosis,(Rothova and Lardenoye, 1998; Steahly, 1988; Verougstraete et al., 2001) and are considered suggestive of ocular sarcoidosis. However, the patients in our series did not have elevated ACE levels or pulmonary involvement on chest imaging typically associated with systemic sarcoidosis. They did, however, have extrapulmonary gallium-67 uptake in the lacrimal glands with additional involvement of the parotid glands in 2 cases. The lacrimal glands are the most common extrapulmonary site of gallium-67 uptake, and the most characteristic pattern of extrapulmonary gallium uptake is the “panda sign” (bilateral lacrimal and parotid gland uptake).(Sulavik et al., 1990). Increased gallium-67 uptake in the lacrimal and parotid glands is not specific for sarcoidosis but can also be seen in tuberculosis, lymphoma, and Sjogren syndrome. The bilateral involvement, African-American predominance, negative serological testing, and negative PPD skin testing or prior treatment for tuberculosis in our series made these alternate diagnoses unlikely The patients in our series were presumed to have an isolated ocular form of sarcoidosis without any systemic involvement. Three patients with periphlebitis and macular edema were treated with a periocular injection of triamcinolone, while one patient with peripheral neovascularization was treated with scatter laser photocoagulation and mycophenolate mofetil. All patients had complete resolution of their disease, supporting an inflammatory etiology for their clinical findings. The utility of gallium-67 scintigraphy in the routine investigation of sarcoidosis has not been established. However, gallium-67 scintigraphy may be useful in a select group of patients with retinal vasculopathy suggestive of sarcoidosis with a normal systemic work-up including serum ACE and chest imaging. The finding of lacrimal gland involvement with or without salivary gland involvement may suggest the diagnosis of an isolated ocular form of sarcoidosis in these cases. Diagnosis of sarcoidosis ultimately requires histological confirmation. Biopsy of the lacrimal and/or salivary glands, guided by the results of gallium-67 scintigraphy, may be warranted in cases like those presented in this report.