A 32-year-old woman from Mumbai presents with a maculopapular rash on the trunk and extremities, including the palms and soles. She also has condyloma lata in the perianal region, mucous patches in the mouth, and generalized lymphadenopathy. Serological tests show high-titre RPR and positive FTA-ABS. Which is the most common systemic manifestation of secondary syphilis?