Syphilis is a sexually transmitted infection caused by Treponema pallidum (TP), and its prevalence has increased dramatically worldwide in recent years [1]. Given the increased incidence, more attention should be paid to the atypical presentations of primary syphilis in order to prevent further serious complications [2]. We present a case of Follmann balanitis in a middle-aged male patient, which is a rare and atypical presentation of primary syphilis.

A 33-year-old male patient visited our clinic with a painful erythematous plaque with some erosions on the gland penis that had been present for 20 days. There was no history of new medications being introduced, and the patient denied any drug use. The patient reported that the lesion appeared eight days after having unprotected oral and vaginal heterosexual intercourse. A large, erosive, well-defined erythematous plaque over the glans had spread to the foreskin (Figure 1).

No skin lesions or enlarged lymph nodes were present. Herpes simplex virus (HSV) polymerase chain reaction (PCR), bacterial and fungal cultures of swabs from erosive lesions, and serologic tests for human immunodeficiency virus (HIV) and syphilis were among the screening tests for sexually transmitted infections (STIs) that were conducted based on the patient’s sexual history. All the investigation results were negative except for positive Treponema pallidum hemagglutination assay (TPHA) 1/320 and positive rapid plasma regain test (RPR) 1/32. According to the investigation results, we excluded the diagnosis of herpes simplex, mycological infection and bacterial infection, and the diagnosis of Follmann balanitis was made. There was no history of previous syphilitic infection. The patient was treated with a single intramuscular injection of 2.4 million international units of benzathine penicillin, with great improvement achieved within two weeks (Figure 2). After three months, the RPR titer dropped fourfold.

Sexually transmitted infections like syphilis are brought on by T. pallidum infections. Sexual contact is the most common way for transmission to occur. However, studies have shown that nonsexual ways, like mouth-to-mouth transmission of previously chewed food, can also result in syphilis infection [3]. The clinical presentation of syphilis varies widely, despite the fact that it is generally described as progressing through primary, secondary, latent, and tertiary stages. After an incubation period of roughly 21 days, the primary infection typically manifests as a painless genital chancre and inguinal lymphadenopathy [2]. Balanitis refers to the inflammation of the glans caused by a variety of factors. Several pathogens contribute to the development of infectious balanitis, including fungal, bacterial, anaerobic, parasitic, and viral agents. Eugene Follmann first described syphilitic balanitis, and the condition was later named after him [4].

We present a case of Follmann’s syphilitic balanitis, which may be a rare manifestation of primary syphilis. This observation, in our opinion, deserves special attention. As the condition is frequently misdiagnosed as another cause of balanitis, such as herpes simplex or Candida albicans. Follmann balanitis, unlike the “classic” syphilitic chancre, is large, superficial, and painful.

Another drawback is the results of serological testing; Hembert et al. found that 36% of patients with primary syphilis had both negative treponemal and nontreponemal tests, and 60% of patients had a negative nontreponemal test [5]. Salle et al. also reported a case of Follmann balanitis with a negative Venereal Disease Research Laboratory (VDRL) and TPHA [1]. Therefore, even though polymerase chain reaction is not yet commonly used in clinical practice, it is the most effective direct diagnostic assay for detecting Treponema pallidum [1] (Table 1).

Follmann balanitis is an atypical, rare form of primary syphilis that is frequently misdiagnosed as other causes of balanitis. With the increasing incidence of syphilis infection in recent years, clinicians should be aware of the condition and suspect T. pallidum infection in cases presenting with balanitis, especially with a suggestive sexual history. Early management of syphilis can prevent subsequent health care utilization and long-term sequelae.