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PubMed Search: Syphilis

Alcides Chaux, M.D.
Antonio L. Cubilla, M.D.
Page views in 2023: 2,846
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Cite this page: Chaux A, Cubilla AL. Syphilis. website. Accessed April 14th, 2024.
Definition / general
  • Historically called lues
  • U.S. incidence dropped through 2000 but has risen since with more cases in men having sex with men
  • Caused by Treponema pallidum, subspecies pallidum, a microaerophilic spirochete that is pathogenic only to humans
Clinical features
  • Called "the great imitator" because it may mimic other disorders if presentation is unusual
  • 30% transmission rate from sexual intercourse

Primary syphilis:
  • Painless hard chancre (ulcer with indurated and punched out base) at site of inoculation, often in glans
  • Most common affected sites are inner foreskin, coronal sulcus, penile shaft and penile base
  • Chancres are usually solitary

Secondary syphilis:
  • Bacteremic stage with greatest number of organisms in the body
  • Classically has widespread rash (small red macular lesions), including on palms and soles and mucous membranes
  • Condyloma lata, formed by soft, flat topped, moist, red / rose / gray to pale maculopapules, nodules or plaques, is the characteristic anogenital lesion and may become confluent; are common in scrotum
  • May have varied clinical presentation

Tertiary syphilis:
  • Gummatous form is characteristic: granulomas with epithelioid and giant cells, obliterative endarteritis and necrosis
  • Also cardiovascular form and neurosyphilis
  • Accelerated time course occurs with HIV infection (1 year to neurosyphilis)
Case reports
  • Penicillin G
Clinical images

AFIP images
Sharply delineated lesion

Sharply delineated lesion

Two well circumscribed, minimally elevated lesions

Images hosted on other servers:

Primary chancre

Atrophic scar with condylomata lata

Secondary rash / lesions:

Palm, limbs and hands


Face, teeth

"Kissing" lesions

Various images

Microscopic (histologic) description
  • Presence of obliterative endarteritis surrounded by a predominantly plasmocytic infiltrate is characteristic of all stages
  • Spirochetes can be identified in primary and secondary lesions but are difficult to demonstrate in gummas
  • Primary syphilis: ulceration, granulation tissue and obliterative endarteritis at ulcer base; plasma cells and lymphocytes underlying ulcer, endothelial cell proliferation and capillaritis
  • Secondary syphilis: psoriasiform epidermal hyperplasia or spongiform pustular lesions with superficial or deep obliterative endarteritis and lymphoplasmacytic infiltrate at the dermal epidermal junction; perivascular infiltrate and possible granulomas; also nodal involvement with florid follicular hyperplasia, unusually shaped follicles, endothelial swelling and perivascular cuffs of plasma cells and lymphocytes
  • Tertiary syphilis: gummas formed by granulomas with epithelioid and multinucleated giant cells, obliterative endarteritis and necrotic foci
Microscopic (histologic) images

AFIP images

Lesion characterized by acanthosis

Images hosted on other servers:

Perivascular dermal infiltrate

Chorioretinitis of congenital syphilis

Darkfield microscopy

Patchy infiltrate

Epithelioid cells surrounded by lymphomono-nuclear cells

Various images

Positive stains
Electron microscopy images

Images hosted on other servers:

Spirochete in culture

Differential diagnosis
  • Lymphoma: monoclonal lymphoplasmacytic infiltrate; no clinical or laboratory evidence of syphilis
  • Plasma cell myeloma: monoclonal plasma cells, often binucleated; monoclonal gammopathy; no clinical or laboratory evidence of syphilis
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