Sonographic appearance of syphilitic induration mimicking squamous cell carcinoma in the lower lip: a case report

Abstract

Background: Syphilis is a sexually transmitted disease caused by the spirochete Treponema pallidum. Recently, its incidence has been increasing worldwide. We encountered a young woman who presented with induration mimicking squamous cell carcinoma in the lower lip, without major medical conditions.

Case presentation: A 25-year-old Japanese woman presented with a 1-month history of a painless induration in her lower lip. Because squamous cell carcinoma was suspected, a preoperation work up was performed, including laboratory tests, an ultrasonographic examination, and a biopsy. The ultrasonography findings showed an oval-shaped 17 × 11 × 12 mm tumor-like lesion with heterogeneous internal echo and an indistinct border. A pressure test and color Doppler sonography revealed that the lesion was soft with a very abundant blood flow. These findings suggested the possibility of underlying inflammatory causes rather than a neoplastic tumor. Serology tests for syphilis, including the anti-Treponema pallidum antibody and reactive rapid plasma reagin tests, were positive. The biopsy revealed no malignancy. Finally, she was diagnosed as having primary syphilis and treated with amoxicillin for 28 days. The rapid plasma reagin value gradually decreased and the initial induration in her lower lip disappeared.

Conclusion: This case highlights the need for prompt examinations for possible underlying infective causes, such as syphilis, when seeing a painless induration with ulcer in the lip. Ultrasonography was helpful in the differential diagnosis of a tumor-like lesion and should be included in addition to syphilis serology tests, such as anti-Treponema pallidum antibody and rapid plasma reagin tests.

Keywords: Case report; Color Doppler ultrasonography; Dental clinic; Lower lip; Pressure test; Syphilis; Ultrasonography.

Fig. 1

A photograph of the lower lip lesion of a 25-year-old woman with syphilis. A healthy 25-year-old woman presented with a 4-week history of a painless, ulcerative intractable lesion with an indurated margin on her lower lip

Fig. 2

Sonogram of the lesion on the lower lip. A gray-scale and transverse sonogram of the lesion obtained with the patient’s mouth closed. The shape of the lesion was almost oval. A heterogeneous tumor-like lesion of 17 × 11 × 12 mm in size was observed in her left lower lip. The ulcerative lesion was hypoechoic (white arrow). The mandibular teeth are indicated with white arrowheads

Fig. 3

The border of the tumor-like lesion. The border of the lesion was indistinct (yellow arrows)

Fig. 4

A color Doppler sonogram of the tumor-like lesion. A color Doppler sonogram of the tumor-like lesion revealed very abundant blood flow in the heterogeneous sites and poor blood flow in the hypoechoic part of the tumor-like lesion

Fig. 5

A loupe image of the histopathological examination. The histopathological examination (blue arrow head) showed lymphoplasmacytic infiltration around the vessels and appendages in the subepithelial region. No evidence of malignancy was observed

Fig. 6

A photograph of the lower lip lesion after treatment with amoxicillin. Her lip lesion had almost disappeared after 3 months (bold arrow)

Fig. 7

Sonograms of the lesion on the lower lip after treatment with amoxicillin. A gray-scale transverse sonogram (left) and color Doppler sonogram (right) of the lesion at 3 months after the initiation of treatment. Her lip lesion showed remarkable improvement at 3 months after treatment initiation, with only a hypoechoic lesion with blood flow signals remaining

Fig. 8

Patient timeline from unprotected orogenital contact to gradual reduction of the lesion. AMPC amoxicillin, CBC complete blood count, FTA fluorescent treponemal antibody, HBV hepatitis B virus, HCV hepatitis C virus, HIV human immunodeficiency virus, RPR rapid plasma reagin, TP Treponema pallidum