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Painless ulcer on the dorsal aspect of hand

      1. Case presentation

      A previously healthy 47-year-old man presented a 3-month history of progressive proliferative plaque and ulcer on the dorsal aspect of the right hand. Initially, the patient was bitten by an irritable woman savagely during a dispute on a bus. Bleeding from the wound was stopped by local treatment. Six weeks later, the lesion expanded despite the prescription of irregular oral antibiotics in community hospitals. The patient is heterosexual and denied extramarital sex. On physical examination, the ulcer was brownish-red and 7 to 9 cm in diameter. The lesion was not painful, had a smooth base with an elevated firm border, surrounded by well-circumscribed, crusted, erythematous plaques (Fig. 1Panel A). There were no lesions on the patient's palms, soles, and trunk although the patient reported a transmitted macular rash history on the palm. Asymptomatic lymphadenopathies were shown in axillary regions.
      Fig. 1
      Fig. 1Panel A Single ulcer with smooth base and elevated firm border, surrounded by crusted, erythematous plaques. Panel B High magnification showed perivascular infiltrate with numerous plasma cells.
      Fig. 1
      Fig. 1Panel A Single ulcer with smooth base and elevated firm border, surrounded by crusted, erythematous plaques. Panel B High magnification showed perivascular infiltrate with numerous plasma cells.
      What is the diagnosis?

      2. Diagnosis

      Answer:Syphilitic Chancre
      At low magnification, histopathology revealed infiltrated inflammatory cells in dermis. High magnification showed perivascular infiltrate with numerous plasma cells suggestive of primary syphilis (Fig. 1 Panel B). Further Rapid plasma regain test (RPR) was positive at a titer of 1:32, and Treponema pallidum particle agglutination (TPPA) test was reactive, confirming the diagnosis of syphilis. The patient's wife was syphilis negative. After treatment with intramuscular penicillin G benzathine 2.4 million units, the lesion healed completely after two months, leaving pigmentation and atrophic scar.
      Primary syphilitic chancres typically developed one to three weeks after inoculation in the genital area. At least 5% of the syphilitic chancers developed at the extragenital site. Minor skin traumatic lesion resulting from fellatio could facilitate Treponema pallidum invading, and syphilitic chancres could present on other parts of the body.
      • Chiu HY
      • Tsai TF.
      A crusted plaque on the right nipple.
      The 50% infectious inoculum (ID 50) of Treponema pallidum is approximately 57 organisms.
      • Magnuson HJ
      • Thomas EW
      • Olansky S
      • Kaplan BI
      • De Mello L
      • Cutler JC.
      Inoculation syphilis in human volunteers.
      Oral lesions are highly infectious
      • Yu X
      • Zheng H.
      Syphilitic chancre of the lips transmitted by kissing: a case report and review of the literature.
      , therefore we assumed that the active Treponema pallidum could be inoculated onto the biting site of the hand, and irregular oral antibiotics might delay the disease progression.
      Keep vigilance of such usual manifestation can promote timely diagnosis and avoid unnecessary skin biopsy. Syphilis should be considered in the differential diagnosis in patients with unexplained plaque and ulcer after trauma.

      References

        • Chiu HY
        • Tsai TF.
        A crusted plaque on the right nipple.
        JAMA. 2012; 3084: 403-404
        • Magnuson HJ
        • Thomas EW
        • Olansky S
        • Kaplan BI
        • De Mello L
        • Cutler JC.
        Inoculation syphilis in human volunteers.
        Medicine (Baltimore). 1956; 35: 33-82
        • Yu X
        • Zheng H.
        Syphilitic chancre of the lips transmitted by kissing: a case report and review of the literature.
        Medicine (Baltimore). 2016; 9514