Histological Diagnosis of Ocular and Periocular Tuberculosis 1945 - 2020

Ocular tuberculosis is a rare but important differential diagnosis for inflammatory conditions of all eye tissues, including the ocular surface and adnexa. Tissue diagnostics may prove challenging as some ocular tissues are difficult to biopsy and the detection of pathogens may be insensitive. We were interested in how many cases in the archive of the ophthalmopathological laboratory had been diagnosed with (peri)ocular tuberculosis since 1945.

Retrospective analysis of historical records and specimens of the ophthalmopathology laboratory of the eye department at Freiburg university hospital. Systematic re-evaluation of available slides for presence of granuloma, necrosis, giant cells, acid fast bacteria, and chronic as well as acute inflammation, plus comparison of current and historic evaluations. In addition, we describe a recent case with tuberculoma of the iris.

There were 50,418 records archived since 1945, of which 23 specimens taken from 22 patients had been diagnosed as (peri)ocular tuberculosis. Of these, 22 (96%) were archived and available for re-interpretation. Four specimens (17%) had been excised from children. The most common tissues were enucleated eye globes (10/23, 44%), followed by the lacrimal sac (5/23, 22%) and conjunctiva (2/23, 9%). The most frequent histopathological findings were granulomas (23/23, 100%), chronic inflammation (22/23, 96%), giant cells (21/23, 91%), and necrosis (14/23, 61%). An acute inflammatory response was found in 4/23 specimens (17%). Ziehl-Neelsen stains for acid-fast bacteria had been performed in five cases, of which three were positive (60%). The greatest discrepancy between current and historical findings related to the presence of necrosis (59% consensus). In other findings, the consensus was high (78 - 96%). In a recent case of a patient with wasting syndrome attributed to lymphoma, histopathological workup of an iris tumour led to the diagnosis of tuberculosis.

Ocular tuberculosis is a rare but important histopathological differential diagnosis. In the available specimens, the classic finding of necrotizing inflammation was rarest and showed least consensus on histological re-evaluation. Other typical findings, such as giant cells and a predominantly lymphocytic infiltrate, are sometimes not found even with proven presence of Mycobacterium tuberculosis. They should not be considered essential in cases where there is strong clinical suspicion.