Tonic pupil and dermal injuries, is it just what it seems?

This case discusses a 33-year-old male who reported unprotected sex with men (MSM), consulting with a two-month history of night fever and non-painful, non-pruritic skin lesions and, in recent days, blurred vision in his right eye and intermittent headache. Physical examination revealed a widespread maculopapular rash, including on the palms of his hands and soles of his feet (Fig. 1), and marked anisocoria with right pupil mydriatic and hyporeactive to light and accommodation (Fig. 2), with no meningism or other focal neurological signs.

Fig. 1.

Maculopapular and erythematous exanthema on the trunk.

Fig. 2.

Anisocoria due to right pupil mydriatic and hyporeactive to light.

Tests showed the patient to be positive for anti-T. pallidum antibodies with an RPR titre of 1/128 and positive for anti-HIV antibodies (CD4 T-cell count 184 per mm³ and plasma viral load 110,012 copies/ml). Analysis of cerebrospinal fluid (CSF) showed 29 leucocytes/μl with predominance of lymphocytes (75%), glucose 51 mg/dl, proteins 0.84 g/dl and positive VDRL (venereal disease research laboratory test).

With the diagnoses of HIV and neurosyphilis, the patient was given penicillin G sodium in continuous infusion for 14 days, antiretroviral treatment and primary prophylaxis for P. jirovecii. The patient made good progress, with the skin lesions disappearing and pupil contraction returning (Fig. 3).

Fig. 3.

Recovery of right pupillary contraction after 10 days of treatment with penicillin G sodium.

Nowadays, the tertiary forms of neurosyphilis (tabes dorsalis and progressive general paralysis) are rare, but early neurosyphilis is on the increase, especially in MSM with HIV infection.^1,2 Although the most common form of ocular neurosyphilis is uveitis, T. pallidum can affect almost any structure of the eye. The classic Argyll-Robertson pupil tends to accompany tertiary forms, while in our patient (with early syphilis) the mydriatic and non-reactive pupil (mimicking an Adie pupil) was the only manifestation of neurosyphilis; similar cases have even been described with no other signs of early syphilis.³ It is therefore necessary to maintain a high degree of suspicion in the case of any eye disease in MSM, especially if they have HIV, and perform serology for syphilis and, if positive, a lumbar puncture to rule out neurosyphilis.