An unusual presentation of neuro‐ophthalmic syphilis

Abstract

Syphilis is a transmissible infection caused by the spirochete Treponema pallidum, subspecies pallidum (T. pallidum). The Australian annual notification rates of infectious syphilis have more than doubled from 2013 to 2017, and increased fivefold within the indigenous population. With an increasing national incidence, clinicians require an increased awareness of rare presentations. Iris lesions in ocular syphilis have been noted previously, but this appears to be rare. We present a case of an iris mass that was diagnosed as neuro-ophthalmic syphilis. A 51-year-old human immunodeficiency virus (HIV)negative, indigenous, heterosexual man presented with a painful red left eye. Symptoms commenced 4 days prior and included photophobia and reduction in left visual acuity. He denied a significant headache or right eye symptoms. Other relevant clinical history included asymmetrical hearing impairment of unknown duration, which the patient attributed to his occupation. He denied having a regular partner, and only had sexual intercourse with casual female partners. Further history and examination did not reveal any features to suggest an episode of primary syphilis prior to his current presentation. However, approximately 2 weeks prior to presentation, he was prescribed oral flucloxacillin by his local medical practitioner for an index finger cellulitis. Postadministration of a couple doses of oral flucloxacillin, the patient described he had developed a widespread non-pruritic rash and derangement of his liver enzyme tests. The patient had attributed this to flucloxacillin; however, this may have represented early signs of secondary syphilis rather than an antibiotic allergy. The rash and deranged liver enzyme tests had resolved prior to his ophthalmic presentation. Furthermore, there was no known prior history of syphilis testing or treatment for syphilis. Initial ophthalmic examination revealed unaided visual acuities of 6/5 and 6/12 on the right and left respectively. Colour vision was normal and there was no relative afferent pupillary defect. The anterior segment of the left eye demonstrated conjunctival congestion, non-granulomatous inferior keratic precipitates on the cornea and a moderately severe iritis with a large fibrin mass overlying his pupil. Posterior synechiae, inflammatory iris adhesions to the anterior lens capsule, resulted in an irregular and minimally reactive pupil (Fig. 1A). A non-pigmented iris stromal mass was noted (Fig. 1B–D) and measured 2 mm × 3.5 mm at the 11 o’clock pupil margin. The right anterior segment was normal. Posterior eye examination revealed marked bilateral optic nerve head swelling with multifocal chorioretinitis. His syphilis serology revealed a reactive syphilis enzyme immunoassay total antibody, reactive T. pallidum particle agglutination assay and reactive rapid plasma reagin (RPR) test with a titre of 1:64. Cerebrospinal fluid demonstrated a glucose of 2.5 mmol/L (normal 2.2−3.9 mmol/L), elevated protein of 1000 mg/L (normal 150–500 mg/L), elevated white cell count of 178 (normal <5) with 98% mononuclear cells and 2% polymorphs, red cell count of 20 (normal <5), reactive Venereal Disease Research Laboratory (VDRL) assay, and T. pallidum deoxyribonucleic acid (DNA) was detected via nucleic acid amplification testing. He was treated subsequently with 15 days of intravenous benzylpenicillin. Topical steroids and atropine cycloplegia were administered to address the anterior uveitis. Repeat examination at 4 weeks post-completion of therapy showed resolution of the left iris stromal mass (Fig. 1E) with marked improvement in the degree of optic nerve head swelling. His visual acuity improved to 6/4.8 bilaterally. Repeat syphilis serology at this time revealed an adequate fall in his RPR titre to 1:16. The clinical presentation of neuro-ophthalmic syphilis is broad with uveitis or intraocular inflammation being the most common ocular manifestations. Syphilitic uveitis can present as an anterior, intermediate, posterior or panuveitis; as such, patients with uveitis should be considered for syphilis serological testing. Clinical clues to syphilitic uveitis include: multifocal chorioretinitis, punctate inner retinitis and preretinal focal deposits in cases of panuveitis. Other posterior manifestations include retinal vasculitis, necrotising retinitis and serous retinal detachments. Neuro-ophthalmic manifestations comprise: cranial nerve abnormalities (II, III, IV and VI), neuroretinitis, optic neuritis, perineuritis and papillitis. A literature search was conducted on PubMed to ascertain all publications with iris lesions associated with syphilis. We used the terms (‘treponema pallidum’ or ‘syphilis’) AND (‘iris nodule’ or ‘iris mass’ or ‘iris granuloma’ or ‘iris lesion’) into PubMed search and included all articles up to 9 May 2020. The search returned only