The differential diagnosis included oral manifestation of syphilis, lichen planus, lingua geographica, stomatitis, candidiasis and herpes simplex. Further research was performed and polymerase chain reaction (PCR) swab for syphilis on the tongue was positive. PCR for herpes simplex virus type I and II, varicella zoster virus and chlamydia were negative. A potassium hydroxide preparation was negative for candida. Blood testing revealed a positive enzyme immunoassay for syphilis and a VDRL titre of 1:8. The HIV test was negative.
On the basis of the clinical and laboratorial findings, the diagnosis of ‘mucous patches’ was made. Mucous patches, also called plaques muqueuses or snail tracks, is an infrequent manifestation of secondary syphilis.1
Syphilis, a sexually transmitted disease, is caused by a spirochete Treponema pallidum. Acquired syphilis can be classified into different stages, determined by its activity and infectivity phase. The secondary stage of syphilis results from the systemic spread of T. pallidum, occurring weeks or months after the primary infection. Its clinical presentation has a wide variation and includes fever, malaise, headache, sore throat, arthralgias and generalised enlargement of the lymph nodes. Similarly, the cutaneous manifestations vary widely, including a non-pruritic disseminated symmetric maculopapular rash, condylomata lata, corona veneris, lichenoid rash and moth-eaten patchy alopecia.
Oral lesions generally occur in the secondary stage of syphilis, although all stages can exhibit oral disorders. In secondary syphilis, approximately 30% of patients have involvement of the oral cavity. However, oral abnormalities are rarely the solitary manifestation.2 Mucous patches, although often asymptomatic, are highly contagious. The clinical presentation of mucous patches is annular and oval, slightly raised, greyish white plaques surrounding small superficial ulcerations or erosions. The patches may present in a serpiginous distribution, sometimes termed snail track lesions. They can affect the tongue, buccal mucosa, gingivae, pharynx, larynx, tonsils, epiglottis, aryepiglottic fold and rarely the hard palate.3 Mucous patches are regarded as the equivalent of the anogenital located condylomata lata, another mucocutaneous manifestation of secondary syphilis.
Syphilis is a treatable disease, but has serious potential complications if not treated. Furthermore, early recognition can prevent further spread of the disease. As STIs are emerging, clinicians should be aware of the different clinical presentations.4 On suspicion of an STI, oral examination should be performed.