Ocular tuberculosis: a clinicopathologic and molecular study

To analyze the clinical profiles, histopathologic features, and Mycobacterium tuberculosis polymerase chain reaction testing in patients with ocular tuberculosis.

Retrospective case series.

Forty-two patients.

This retrospective study was approved by the Armed Forces Institute of Pathology (AFIP) Institutional Review Board. The AFIP data banks were screened for cases with diagnosis of ocular tuberculosis using key words such as mycobacterium; tuberculosis; and acid-fast bacilli. Files and slides stained with hematoxylin-eosin and acid-fast staining were reviewed by the Division of Ocular Pathology and by the Infectious Diseases and Parasitic Diseases Pathology Branches. When available; blocks and unstained slides were sent to the Doheny Eye Institute; Los Angeles; California; for quantitative polymerase chain reaction (qPCR) analysis to detect Mycobacterium tuberculosis-specific DNA.

Tuberculin skin test (TST) results, as well as the chest radiograph results, were recorded. When acid-fast bacilli were identified in tissue, their locations-ocular or extraocular sites-were recorded. Emphasis was placed on lymph node involvement and any systemic diseases.

In the histopathologic specimens, microscopy revealed a paucity of organisms, and often there were only 1 or 2 organisms associated with or near a giant cell or near an area of necrosis. The qPCR analysis was performed on 6 biopsy specimens. These specimens showed necrotizing granulomatous inflammation from 6 different patients; 3 had positive qPCR results. In 2 of the 3 cases with positive qPCR results, acid-fast bacilli were not found in the tissue sections. In 17 patients, TST results were available; 10 had positive results (60%) and 7 had negative results (40%). Fourteen chest radiograph results were submitted, and 8 (57%) of 14 patients had normal chest films.

This study suggests that in dealing with those populations at increased risk of tuberculosis (e.g., immigrants from endemic areas and human immunodeficiency virus-infected patients) or patients receiving biologic therapy, the ophthalmologist should endeavor to entertain this diagnosis and to rely on the support of infectious disease specialists and pulmonologists to help solidify the diagnosis, because the current methods for the diagnosis have limited sensitivity.