Syphilis

Definition

  • Infection with Treponema pallidum, acquired sexually or transmitted vertically

Pathology

Syphilis, treponema pallidum, the organism causing syphilis
Treponema pallidum, the organism causing syphilis. Image by CDC, Wikimedia Commons, Public domain.
  • Endarteritis obliterans with perivascular plasma cell infiltrate
  • Gummata are granulomatous necrotic lesions of tertiary disease

Clinical Features

Congenital

  • Parrot pseudoparalysis, a painful limb held still from osteochondritis or epiphyseal separation
  • Wimberger sign, bilateral destruction of the proximal medial tibial metaphyses
  • Symmetrical periostitis of long bones
  • Sabre tibia, anterior bowing from dense endosteal and periosteal new bone
  • Clutton joints, painless bilateral knee effusions in late childhood
  • Hutchinson triad of notched incisors, interstitial keratitis and deafness
  • Frontal bossing and saddle nose

Acquired

  • Secondary syphilis may cause polyarthralgia and periostitis, often of the tibia
  • Tertiary gummatous osteitis of the skull, tibia and clavicle
  • Tabes dorsalis causes Charcot neuropathic arthropathy, most often of the knee

Investigations

  • Non treponemal tests such as RPR to screen and monitor treatment
  • Treponemal tests such as TPPA to confirm
  • X-ray shows periostitis, sclerosis and lytic gummatous lesions

Differential Diagnosis

Management

  • Benzathine penicillin G, regimen depending on stage
  • IV penicillin for congenital and neurosyphilis
  • Notify and trace contacts
  • Bracing and protected weight bearing for Charcot joints
  • Arthroplasty in Charcot knees carries high instability and failure rates

Reviewed by Professor Phong Tran, Head of Orthopaedic Surgery, Western Health. Last updated 10 October 2026.