We present a case of atypical presentation of secondary syphilis with extensive lymph node involvement and pulmonary lesions, initially suspected as lymphoma. The patient presented with weight loss, dry cough, chest pain, palpable lymph nodes in several peripheral chains, and multiple pulmonary nodules and masses on chest imaging. The key features for secondary syphilis diagnosis were a lymph node biopsy suggestive of reactive lymphadenopathy, positive serologic tests for syphilis, and complete recovery after antisyphilitic treatment.