Granulomatous conjunctivitis is less common than papillary and follicular conjunctivitis and has both infectious and noninfectious causes. Clinically, the nodular elevations of granulomatous conjunctivitis may be difficult to distinguish from follicles, but the clinical history and systemic symptoms may point to the diagnosis. See BCSC Section 8, External Disease and Cornea, and Section 9, Uveitis and Ocular Inflammation, for additional discussion of granulomatous conjunctivitis.
Figure 5-5 Schematic representations of papillary and follicular conjunctivitis. A, In papillary conjunctivitis, the conjunctival epithelium (blue line) extends over fine projections of blood vessels (red) and fibrous tissue, and the stroma contains eosinophils (pink circles), lymphocytes, and plasma cells (blue circles).B, In follicular conjunctivitis, the conjunctival epithelium (blue line) overlies lymphoid follicles in the superficial stroma that have a paler germinal center surrounded by a darker corona (central pale blue surrounded by purple). The surrounding stroma contains lymphocytes and plasma cells (small blue circles).
(Courtesy of Patricia Chévez-Barrios, MD.)
Figure 5-6 Papillary conjunctivitis. A, Clinical photograph. Papillae efface the normal palpebral conjunctival surface and form a confluent cobblestone pattern. B, Low-magnification photo-micrograph shows the characteristic closely packed, flat-topped papillae with central fibrovascular cores (arrows). The normal meibomian glands (M) of the tarsus are also shown.
(Part A courtesy of Harry H. Brown, MD; part B courtesy of George J. Harocopos, MD.)
Figure 5-7 Follicular conjunctivitis. A, Clinical photograph showing follicles, which occur only in the fornix. B, High-magnification photomicrograph shows a lymphoid follicle and the boundary between the germinal center and the mantle zone (arrowheads). Note the paler, relatively larger, immature lymphocytes in the germinal center compared with the darker, small, mature lymphocytes in the corona.
(Part A courtesy of Anthony J. Lubniewski, MD; part B courtesy of George J. Harocopos, MD.)
Granulomatous conjunctivitis occurring in association with ipsilateral regional lymphadenopathy is known as Parinaud oculoglandular syndrome. Many organisms, often atypical ones such as Bartonella henselae, can cause this syndrome. The diagnosis can be made by using cultures, serologic testing, polymerase chain reaction analysis, or a combination of these. In some cases, special stains such as Gram, acid-fast, or silver stain may be useful for identifying organisms in biopsy tissue. When conjunctival biopsy is performed, the granulomas in infectious granulomatous conjunctivitis typically show central necrosis (caseating granulomas).
A presumably noninfectious cause of granulomatous conjunctivitis is sarcoidosis, a systemic disease that may involve all the ocular tissues, including the conjunctiva. It manifests as small tan nodules without overt inflammatory signs, primarily in the lower forniceal conjunctiva (Fig 5-8A). Conjunctival biopsy can be a simple, minimally invasive way of providing diagnostic confirmation of this systemic disease. Histologically, noncaseating granulomatous nodules (round to oval aggregates of epithelioid histiocytes with or without multinucleated giant cells) are present within the conjunctival stroma, typically with a cuff of lymphocytes and plasma cells (Fig 5-8B). Central necrosis is not characteristic and, if present, suggests an infectious etiology. To ensure that granulomas are not missed in the biopsy tissue, step-sectioning of the paraffin block is done, similar to a temporal artery biopsy. The histologic findings are not pathognomonic for sarcoidosis and must be correlated with clinical findings after infectious causes of granulomatous inflammation have been excluded by special stains and/or cultures.
Figure 5-8 Sarcoidosis. A, Clinical photograph shows granulomas (arrows) of the conjunctiva in a patient with sarcoidosis. B, Histology shows a noncaseating granuloma with pale-staining histiocytes, including a multinucleated giant cell (arrowhead). Note the small cuff of lymphocytes and plasma cells.
(Courtesy of George J. Harocopos, MD.)
Foreign bodies are another cause of granulomatous conjunctivitis, as the surface of the eye is continually exposed to dust, hair, or other foreign material. Some foreign bodies may be transient and/or inert, whereas others may become embedded and incite a foreign-body reaction, identifiable histologically as epithelioid histiocytes and multinucleated giant cells surrounding the foreign material. Viewing the tissue section under polarized light may help reveal the presence of foreign material (Fig 5-9).
Bui KM, Garcia-Gonzalez JM, Patel SS, Lin AY, Edward DP, Goldstein DA. Directed conjunctival biopsy and impact of histologic sectioning methodology on the diagnosis of ocular sarcoidosis. J Ophthalmic Inflamm Infect. 2014;4(1):1–5.
Excerpted from BCSC 2020-2021 series: Section 4 - Ophthalmic Pathology and Intraocular Tumors. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.