Kyrieleis Arteriolitis: All revealed

Case Study

A 29-year-old immunocompetent male presented with blurred vision and floaters in his left eye for one week. He reported mild ocular discomfort and photophobia.

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There was no significant systemic history. Best-corrected visual acuity was 20/25 in the affected eye and 20/20 in the fellow eye.

Anterior segment examination revealed mild anterior chamber cells. Fundus examination of the left eye demonstrated focal necrotizing retinitis in the peripheral retina with associated vitritis.

Segmental, discrete, whitish deposits were observed along the retinal arterioles, giving a beaded appearance. The veins were relatively spared.

Fluorescein angiography (FA) showed minimal leakage from the affected arterioles without significant staining of the vessel wall.

Optical coherence tomography (OCT) revealed mild inner retinal hyperreflectivity adjacent to areas of active retinitis.

Polymerase chain reaction (PCR) analysis of aqueous humor confirmed herpes simplex virus infection.

The patient was diagnosed with acute retinal necrosis (ARN) associated with Kyrieleis arteriolitis and was treated with systemic antiviral therapy. The arteriolar plaques gradually resolved with treatment.

Disease Entity

Kyrieleis arteriolitis is a distinctive form of segmental retinal arteriolar inflammation characterized by the presence of focal, white, bead-like deposits along retinal arterioles.

These deposits are classically associated with infectious posterior uveitis, particularly toxoplasmosis and herpetic retinitis, including acute retinal necrosis.

First described by Kyrieleis in 1933, this condition is considered a clinical sign rather than a standalone disease entity. It represents a specific vascular response to intraocular infection or inflammation.

The defining feature is the presence of segmental intra-arteriolar plaques that appear as discrete, refractile white lesions aligned along the course of retinal arterioles, often adjacent to areas of active retinitis.

Pathophysiology

The exact pathogenesis of Kyrieleis arteriolitis remains incompletely understood, but it is believed to involve localized inflammatory deposition within or adjacent to the retinal arteriolar wall.

Proposed mechanisms include:

Deposition of inflammatory cells or immune complexes within the vessel wall
Focal endothelial dysfunction
Perivascular infiltration secondary to adjacent retinal infection

Unlike typical retinal vasculitis, Kyrieleis arteriolitis appears to involve intraluminal or intramural deposition rather than diffuse perivascular inflammation.

Histopathologic correlation is limited, but clinical imaging suggests that the plaques are non-occlusive and do not significantly impair blood flow.

An important distinguishing feature is that these lesions typically do not exhibit significant leakage on fluorescein angiography, indicating relative preservation of vascular integrity.

Epidemiology

Kyrieleis arteriolitis is rare and occurs in association with specific infectious retinal conditions.

It is most commonly reported in:

Ocular toxoplasmosis
Acute retinal necrosis (ARN)
Other herpetic retinitides

The condition can occur in both immunocompetent and immunocompromised individuals, depending on the underlying cause.

There is no clear age, sex, or racial predilection, as the epidemiology reflects that of the associated infectious diseases.

Clinical Features

Symptoms are primarily related to the underlying retinal infection rather than the arteriolitis itself.

Common presenting symptoms include:

Blurred vision
Floaters
Photophobia
Mild ocular discomfort

The onset is typically subacute.

Visual acuity varies depending on:

Location of retinitis
Degree of vitritis
Macular involvement

Kyrieleis plaques themselves are asymptomatic but serve as an important diagnostic clue.

Examination Findings

Anterior Segment

Mild anterior chamber inflammation may be present
Keratic precipitates in some cases

Posterior Segment

Characteristic findings include:

Segmental, white, bead-like deposits along retinal arterioles
Sparing of retinal veins
Adjacent areas of active retinitis
Vitritis of variable severity

The plaques are typically:

Discrete and well-defined
Located along the length of arterioles
Non-contiguous (segmental distribution)

Fluorescein Angiography (FA)

FA findings are distinctive:

Minimal or no leakage from affected arterioles
No significant staining of vessel walls
Normal or near-normal perfusion

This helps differentiate Kyrieleis arteriolitis from true retinal vasculitis.

Optical Coherence Tomography (OCT)

Localized inner retinal hyperreflectivity near areas of inflammation
Possible disruption of retinal layers in necrotizing retinitis

Optical Coherence Tomography Angiography (OCTA)

Preserved flow in affected arterioles
No significant capillary dropout attributable to plaques

Differential Diagnosis

Kyrieleis arteriolitis should be differentiated from other forms of retinal vascular inflammation.

Key differential diagnoses include:

Retinal vasculitis (e.g., Behçet disease, sarcoidosis)
Frosted branch angiitis
Embolic phenomena
Infectious retinal vasculopathy

In retinal vasculitis:

There is diffuse perivascular sheathing
FA shows leakage and staining

In embolic disease:

Lesions are typically located at vascular bifurcations
Associated with vascular occlusion

The absence of leakage on FA and the characteristic segmental arteriolar plaques are key distinguishing features.

Diagnosis

Diagnosis is clinical and based on recognition of characteristic fundus findings in the context of infectious retinitis.

Key diagnostic elements include:

Segmental white plaques along retinal arterioles
Association with active retinal infection
Minimal leakage on fluorescein angiography
Sparing of veins

Additional investigations are directed toward identifying the underlying cause:

PCR testing for viral pathogens
Serologic testing for toxoplasmosis
Imaging as indicated

Kyrieleis arteriolitis itself does not require separate diagnostic testing.

Management

Management is directed at the underlying infectious etiology, as Kyrieleis arteriolitis resolves with treatment of the primary condition.

Infectious Causes

Antiviral therapy (e.g., acyclovir) for herpetic infections
Anti-toxoplasma therapy (e.g., pyrimethamine, sulfadiazine)

Adjunctive Therapy

Corticosteroids may be used to control inflammation once antimicrobial therapy is initiated

The arteriolar plaques typically regress gradually with successful treatment.

No specific therapy is required for the vascular lesions themselves.

Prognosis

The prognosis of Kyrieleis arteriolitis depends on the underlying retinal disease.

Key points:

The arteriolar plaques are generally reversible
They do not typically cause vascular occlusion
Visual outcome is determined by the severity and location of retinitis

With appropriate treatment, the plaques often resolve without permanent vascular damage.

However, complications from the primary infection—such as retinal necrosis or scarring—may affect visual prognosis.

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References

American Academy of Ophthalmology. Basic and Clinical Science Course (BCSC): Uveitis and Ocular Inflammation. San Francisco, CA: AAO; latest edition.
Yanoff M, Duker JS. Ophthalmology. 5th ed. Elsevier; 2019.
Kyrieleis W. Über arterielle Gefäßveränderungen bei Chorioretinitis. Klin Monbl Augenheilkd. 1933;91:741–746.
Cunningham ET Jr, Short GA. Kyrieleis plaques in ocular toxoplasmosis. Ophthalmology. 1998;105(6):1141–1145.
Coats DK, Paysee EA. Kyrieleis arteriolitis is associated with acute retinal necrosis. Am J Ophthalmol. 2001;131(3):394–396.
Pichi F, Ciardella AP, Cunningham ET Jr. Imaging of infectious retinal vasculitis. Ophthalmol Retina. 2018;2(6):563–575.