SYPHILIS
Syphilis (lues) is a sexually transmitted disease of mankind caused
by the spirochette Treponema pallidum.
Stages of syphilis:
1. Primary (the chancre).
2. Secondary (disseminated).
3. Tertiary (with lesions of deep
organs following a latent period of 2 to 20 years or more).
The chancre develops at the site of
inoculation in 10 to 90 days (average 21 days) and has a characteristic “luetic
vasculitis”, in which endothelial cells proliferate and swell, and the walls of
the vessels become thickened by lymphocytes and fibrous tissue.
Morphology
In primary Syphilis, the chancre is a slightly elevated, firm, reddened papule,
up to several centimeters in diameter that erodes to create a clean-based,
shallow ulcer. Histologically,
the chancre contains an intense infiltrate of plasma cells, with scattered
macrophages and lymphocytes and an obliterative endarteritis. The
regional nodes are usually enlarged and may show nonspecific acute or chronic
lymphadenitis, plasma cell-rich infiltrates, or focal epithelioid granulomas.
The combination of chancre, lymphangitis, and lymphadenitis is called primary syphilitic complex.
Secondary Syphilis. It presents as a
widespread skin rash (pox)
of varying appearance, ulceration of mucous membranes, generalized lymphadenopathy,
damage to various individual organs and tissues. There are constitutional
effects – particularly fiver and anemia.
The essential pathology is the
presence of very numerous spirochaetes accompanied by focal infiltration of
lymphocytes, plasma cells and macrophages with mild arteritis. Infectivity is
very high. Tissue destruction is minimal and healing occurs without scarring. A
latent stage of long duration is followed in 35% of cases by tertiary syphilis.
Tertiary (Late)
Syphilis.
The lesions, which may occur at any time for many years after healing of the
secondary phase, offer striking contrasts. This stage is characterized mainly
by local destructive lesions, the result of cell-mediated immune reactions
(T-cells) causing necrosis of tissue. It occurs
years after the initial infection and most frequently involves the aorta, the
central nervous system, and the liver, bones and testes (gummas).
The main forms are:
1. Gumma.
·
This is a localized area of necrosis, which may affect large parts
of any organ or tissue but particularly bones, testis and liver and looks like white-gray and rubbery formation.
·
In the liver, gumma may produce the
coarsely nodular pattern of cirrhosis, termed hepar lobatum because of the
simulation by the deep scars of multiple lobes.
·
Bone and joint gummas lead to areas
of cortical and articular destruction. Pathologic features and
joint immobilization may result.
·
Testicular gummas often cause
painless enlargement of the affected testis, thus simulating a tumor
·
Histologically, the gummas contain a
center of coagulated, necrotic material and margins composed of plump or
palisaded macrophages and fibroblasts surrounded by large numbers of
mononuclear leukocytes, chiefly plasma cells.
2. Syphilitic
aortitis. The aorta is affected by an
infiltration of lymphocytes and plasma cells beginning around the vasa vasorum
and extending into the media, causing weakening due to focal destruction
(windowing) of the specialized elastic tissues. There is compensatory irregular
thickening of the intima (tree-bark
appearance), but the important effect is expanding aneurysm
formation.
3. Neurological
Syphilis. Neurosyphilis
takes one of several forms, designated meningovascular Syphilis, tabes dorsalis,
and general paresis.
·
Meningovascular – mainly affects the
meningeal blood vessels and causes neurological impairment secondary
·
Parenchymatous:
a) General paralysis of the insane – severe
destruction of cerebral tissue, atrophy of convolutions, enlargement of
ventricales;
b) Tabes dorsales – the damage
specifically affected the posterior roots and columns of spinal cord – is
associated with characteristic clinical symptoms due to lose of proprioceptive
sensation in the legs.
Congential syphilis is most severe when the mother’s infection is recent.
In perinatal and infantile Syphilis, a diffuse rash develops. Syphilitic
osteochondritis and periostitis affect all bones. Destruction of the vomer
causes collapse of the bridge of the nose and, later on, the characteristic
saddle nose deformity. Periostitis of the tibia leads to excessive new bone
growth on the anterior surfaces and anterior bowing, or saber shin. The liver
is often affected severely in congenital syphilis. Diffuse fibrosis permeates lobules
to isolate hepatic cells into small nests. Gummas are occasionally found in the
liver, even in early cases. The lungs may be affected by a diffuse interstitial
fibrosis.
The late-occurring
form of congenital syphilis is distinctive for the triad of interstitial
keratitis, Hutchinson's teeth, and eight-nerve deafness.
