Pulmonary syphilis mimicking lung metastasis: a case report

Syphilis, due to Treponema pallidum, has various clinical presentations, in particular in patients who are tested positive for HIV, and the nickname of "the great imitator" is very well deserved.

A 54-year-old HIV-positive man was referred for multiple subpleural bilateral lung nodules without mediastinal lymphadenopathy on a computedtomography (CT) of the chest carried out for symptoms combining dry cough, sweats, night chills, right basi-thoracic pain, and a weight loss of 4 kg in a few weeks. His medical history revealed pneumocystis infection and secondary syphilis, occurring 10 and 8 years ago, respectively. His regular partner did not have any symptoms and deranged biological analysis. The clinical examination was normal except for a maculopapular rash on the back, hands, and forearms. A skin biopsy was performed which revealed the presence of T. Pallidum. A CT-guided percutaneous needle aspiration of a pulmonary nodule met the diagnosis of necrotic inflammatory granuloma. A single dose of benzathine penicillin 2.4 million units led to the negative conversion of Venereal Disease Research Laboratory test and ELISA antitreponema antibody index, and the CT scan carried out 3 months later showed a quasi-resolution of several lung nodules.

Pulmonary involvement in secondary syphilis is very rare in comparison to congenital or tertiary syphilis. However coinfection with HIV increases the frequency of atypical presentation of the disease. Despite the presence of usual clinical criteria for the diagnosis of pulmonary involvement and an HIV disease controlled with antiretroviral treatment, a CT-guided fine needle aspiration of a nodule was done to rule out neoplastic disease or other infection.

With the rise of syphilis cases, physicians have to be aware of non-specific clinical presentation of the disease in particular in case of coinfection with HIV.