• HPV
• HSV
• syphilis

In paediatric patients, sexually transmitted infections are not always in the mind of clinicians, but their occurrence should not be forgotten. Syphilis is the great imitator, simulating a large variety of diseases, from inflammatory to oncological diseases, as well as other infectious conditions.1

We report the case of a 15-year-old male adolescent patient, admitted to the emergency room with loose bloody diarrhoea, extensive anal ulceration, with cobblestone mucosa aspects (figure 1) and weight loss of 5 kg in the past 8 weeks. Clinical observation was thus suggestive of inflammatory bowel disease, and the patient was admitted to the paediatric gastroenterology ward for further study. Genital examination was only performed after admission and revealed scrotal erythema and tumid plaques of the penis. Dermatological observation was then requested, and the lesions were suggestive of syphilides (see online supplementary figure 3), with no other signs of primary or secondary syphilis (see online supplementary figures 4 and 5). One of these lesions was biopsied and was histologically typical of syphilis. The patient denied any previous sexual contact, but Venereal Disease Research Laboratory (VDRL) and Treponema pallidum haemagglutination antibody tests were positive (VDRL titre 1/128, T pallidum haemagglutination antibody titre 1/1280). Screening for other sexually transmitted infections was negative, including lymphogranuloma venereum-specific DNA from rectal swab specimens and HIV serology.

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Figure 1

Cobblestone anal mucosa and anal ulcers.

Benzatinic penicillin 2 400 000 IU once per week for 2 weeks was administered with full regression of diarrhoea, anal (figure 2) and genital lesions, thus suggesting that the proctological symptoms were consistent with treponemic proctitis in secondary syphilis. VDRL titre was negative 3 months after first penicillin administration.

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Figure 2

Marked improvement of anal inflammation and ulceration shortly after benzathine penicillin treatment.

Later, the patient was assumed to have had sexual intercourse with a male older partner that he met on the internet. This detail raised legal issues because of the patient's age, and the case was communicated to the authorities.

Proctitis is a rare presentation of syphilis, with ulceration and diarrhoea invariably present, but lacking pathognomonic clinical symptoms.1 ,2 It is difficult to diagnose and is occasionally mistreated. The confirmation of this diagnosis may be obtained after successful penicillin therapy, which makes further investigations unnecessary, namely endoscopic procedures or biopsy.3 ,4 Although sexually transmitted proctitis represents a small proportion of the overall number of cases, among men who have sex with men the incidence of this condition is higher. Causative agents may include Neisseria gonorrhoeae, Chlamydia trachomatis, T pallidum and herpes simplex.5 The clinician must keep these diseases in mind while formulating a differential diagnosis for the cause of proctitis, even in children and adolescents.