Abstract

Syphilis is a sexually transmitted infection (STI) caused by treponema pallidum. Its rash usually affects the trunk and limbs extensively, including the palms and soles of the feet. Secondary syphilis confined to the face is extremely rare. We report a case of annular rupioid secondary syphilis, which was misdiagnosed as verruca vulgaris. The patient's lesions were confined to the face and resembled oyster shells. According to epidemiological history, clinical presentation, non-treponemal tests, treponemal tests, and effective benzathine penicillin G treatment, confirmed secondary syphilis.

Keywords

Introduction

Syphilis is a highly contagious sexually transmitted disease (STD) (Stafford et al., 2019). The most common cutaneous manifestation of secondary syphilis is the generalized non-pruritic maculopapular rash. It usually involves the palms and soles of the feet, but may also present as papular, nodular, nodular ulcerative, follicular, pustular, annular, and lichenoid eruptions (Qian and Ma, 2019). Rupioid syphilis is relatively rare, and it usually manifests as skin all over the body (Liu and Ma, 2021). In this case, we present a case of a young woman who developed an annular oyster shell-like secondary syphilis of the face. After consulting domestic and foreign literature in the past ten years, this is the first reported case of annular rupioid secondary syphilis confined to the face. We analyzed the reasons why this is prone to misdiagnosis and some to pay attention to in the diagnosis.

Case Report

A 24-year-old woman had a facial rash for three months with mild pruritus. The patient developed erythema, papules and pustule on the forehead with no inducement 3 months ago. The skin lesions gradually expanded and showed ring-shaped changes. Initially, the clinic diagnosed it as tinea faciale, but the antifungal treatment was ineffective. Lesions continued to develop and the margins thickened, crusted, and rough surfaced with scales, and the itching increased. Later, it was suspected to be verruca vulgaris, and cryotherapy was ineffective.

The patient was previously in good health, was unmarried and had no children. She denied any personal or family history. Physical examination: palpable swollen lymph nodes behind the ear, moderate in quality and movable, and other system examinations showed no abnormality. Dermatology situation: The two annular plaques are about 3 cm in diameter on the forehead, with clear borders and dyke-like raised edges, covered with thick brownish-red scaly scabs that do not peel off easily. The Auspitz sign is negative, and they look like oyster shells, with dark red infiltration at the base and around (Figure. 1a). In the scalp, trunk, limbs, and perianal area, no skin lesions were found.

Figure 1(a) The forehead has two well-demarcated annular plaques, with the edges of a dike-shaped, covered with thick black and red scaly scabs that look like oyster shells. The base and surrounding lesions showed red infiltration. (b) After one week of treatment, the raised edges of the forehead lesions flattened and thinned, and the dark brown oyster shell-like scabs fell off, leaving only red patches and a few scales.

Laboratory tests: complete blood count, urine routine, and antinuclear antibodies, all negative. No mycelium or spores were found in direct microscopic examination of fungus from two facial lesions. The acetic acid test for skin lesions is negative. Serological tests showed positive results for treponema pallidum particle agglutination assay (TPPA), positive rapid plasma reagin (RPR) (1:64), and negative HIV serotest. The patient refused pathological biopsy. Repeatedly asked about the medical history, the patient admitted to having unprotected sex with a netizen within the last year, but denied oral sex. This netizen frankly confessed that he had syphilis 3 years ago. Our female patient denied previous painless nodules and ulcers on the external genitalia and anus, and she denied skin lesions on skin other than the face. The diagnosis was annular rupioid secondary syphilis. (References: Chinese diagnostic standard (Wang, 2020)) The patient was given benzathine penicillin G (2.4 million units) once a week, intramuscularly on both sides of the buttocks. After one week of treatment, the facial lesions significantly improved. The bulge at the edge of the lesions turned thin, and the oyster shell-like black-brown scabs fell off, leaving only dark red patches and a small number of scales attached. Itching symptoms disappear (Figure. 1b). After three weeks of syphilis treatment, the facial rash subsided, leaving only light red pigmentation and no scar. After 3 months, the repeat TPPA was positive and the RPR titer was reduced to 1:4. Her treatment was continued and followed up, and the skin lesions did not recur.

Discussion

Secondary syphilis, also known as "the great imitator", has a wide range of manifestations (Forrestel et al., 2020). Rupioid secondary syphilis is relatively rare. It is a very rare subtype of pustular syphilis. It is characterized by pustules and papules covered with thick oyster like scabs. This kind of syphilis usually involves the skin all over the body (Bhagwat et al., 2009). It usually affects patients with malnutrition or other chronic diseases. In rare cases, it may also occur in patients with normal immune function. Liu, JW previously reported a healthy man with multiple scattered erythematous plaques, conical, oyster shell-shaped, dirty-looking, hyperkeratotic crusts all over his body, diagnosed as rupioid secondary syphilis (Liu and Ma, 2021). However, in our case, the patient was previously in good health, and the rash was only confined to the face, which is extremely rare. The patient's rash was few and limited in extent, and she had the possibility of ignoring previous transient skin lesions. Therefore, we considered not excluding secondary recurrent syphilis. Due to the atypical shape and location of the skin lesions and the interference of pruritic symptoms, the diagnosis process is more challenging, which has led to patients being misdiagnosed as having verruca vulgaris and other skin diseases, resulting in a period of wrong treatment. This case should be differentiated from tinea faciale, seborrheic dermatitis, psoriasis, common warts, granuloma annulare, mycosis fungoides (MF), sweet syndrome, erythema annulare centrifugum, subacute cutaneous lupus erythematosus, and other skin diseases. Finally, we confirmed the patient's diagnosis of annular rupioid secondary syphilis by sexual life history, clinical manifestations, serological examination, and effective benzathine penicillin G treatment (Re and Dm, 2005).

Histopathology is often regarded as the gold standard when encountering skin diseases that are difficult to diagnose. However, the histopathological results of syphilis are often non-specific, so it is difficult to make a definite diagnosis based on them alone (Sakthivel et al., 2018). Moreover, its histopathology is still a "great imitator."(Pournaras et al., 2005). A previous report described a patient with a histopathological and immunofluorescence presentation of bullous pemphigoid, but an ultimately definitive diagnosis of secondary syphilis (Lawrence and Saxe, 1992). Especially, this case was a young female patient, whose skin lesions only lie on the face, and she worried about scars left by pathological biopsy. Doctors should be alert to atypical pleomorphic rash on the face. In a similar situation, doctors should put the screening of syphilis in the first place of diagnostic thinking. Timely provision of economical, efficient, and non-invasive serological tests for syphilis is the key to avoiding misdiagnosis and missed diagnosis. Early syphilis is highly contagious, less destructive, easily cured, and usually leaves no residual effects (Scott and Flint, 2005). And once the delayed treatment develops into late syphilis, it will cause irreversible, permanent damage to the organs and can even be life-threatening (Peeling et al., 2017). This not only delays the individual, but more importantly, can spread to more contacts as a result. It puts a huge burden on society and deserves our deepest consideration.

Conclusion

We reported a rare case of a 24-year-old female with annular oyster shell-like secondary syphilis confined to the face. The symptoms were successfully controlled after patient received benzathine penicillin G treatment. In this article, we have emphasized that when the clinician is faced with such rare and confined to the face lesions, the possibility of syphilis should be considered, and a serologic test for syphilis should be given as early as possible.

Conflict of Interest

None

Funding source

No funding to declare.

Acknowledgments

We thank all the clinical staff for their dedication to the patient care.

Ethical approval

Informed consent and permission for publication of medical images were taken from the patient.

Declaration of interests

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

The authors declare the following financial interests/personal relationships which may be considered as potential competing interests:

References

Forrestel AK, Kovarik CL, Katz KA. Sexually acquired syphilis: Historical aspects, microbiology, epidemiology, and clinical manifestations. J Am Acad Dermatol 2020;82:1–14. https://doi.org/10.1016/j.jaad.2019.02.073.Wang Q-Q. Guidelines for the diagnosis and treatment of syphilis, gonorrhea, and genital Chlamydia trachomatis infections. Chin J Dermatol 2020; 53:168–9. https://doi.org/10.35541/cjd.20190808.Article InfoPublication History

Accepted: July 8, 2022

Received in revised form: July 7, 2022

Received: June 2, 2022

Publication stageIn Press Journal Pre-ProofIdentification

DOI: https://doi.org/10.1016/j.ijid.2022.07.028

Copyright

© 2022 The Author(s). Published by Elsevier Ltd on behalf of International Society for Infectious Diseases.

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