Page 691 - Robbins Basic Pathology by Vinay Kumar, Abul K. Abbas, Jon C. Aster

Chancroid (Soft Chancre)
Chancroid, sometimes called the “third” venereal disease
(after syphilis and gonorrhea), is an acute, ulcerative infec-
tion caused by Haemophilus ducreyi, a small, gram-negative
coccobacillus. The disease is most common in tropical and
subtropical areas and is more prevalent in lower socioeco-
nomic groups, particularly among men who have regular
contact with prostitutes. Chancroid is one of the most common
causes of genital ulcers in Africa and Southeast Asia, where it
serves as an important cofactor in the transmission of HIV
infection. Chancroid probably is underdiagnosed in the
United States, because most STD clinics do not have facili-
ties for isolating H. ducreyi and PCR-based tests are not
widely available.
MORPHOLOGY
At 4 to 7 days after inoculation, a tender, erythematous
papule develops on the external genitalia. In male patients,
the primary lesion is usually on the penis; in female patients,
most lesions occur in the vagina or periurethral area. Over
the course of several days the surface of the primary lesion
erodes to produce an irregular ulcer, which is more likely
to be painful in males than in females. In contrast with the
primary chancre of syphilis, the ulcer of chancroid is not
indurated, and multiple lesions may be present. The base of
the ulcer is covered by shaggy, yellow-gray exudate. The
regional lymph nodes, particularly in the inguinal region,
become enlarged and tender in about 50% of cases within 1
to 2 weeks of the primary inoculation. In untreated cases,
the inflamed and enlarged nodes (buboes) may erode the
overlying skin to produce chronic, draining ulcers.
On microscopic examination, the ulcer of chancroid con-
tains a superficial zone of neutrophilic debris and fibrin, with
an underlying zone of granulation tissue containing areas of
necrosis and thrombosed vessels. A dense, lymphoplasma-
cytic inflammatory infiltrate is present beneath the layer of
granulation tissue. Coccobacillary organisms sometimes are
demonstrable in Gram- or silver-stained preparations, but
they often are obscured by the mixed bacterial growth fre-
quently present at the ulcer base. A definitive diagnosis of
chancroid requires the identification of H. ducreyi on special
culture media that are not widely available from commercial
sources; even when such media are used, sensitivity is less
than 80%. Therefore, the diagnosis often is based on clinical
grounds alone.
Granuloma Inguinale
Granuloma inguinale is a chronic inflammatory disease
caused by Calymmatobacterium granulomatis, a minute,
encapsulated coccobacillus related to the Klebsiella genus.
This disease is uncommon in the United States and western
Europe but is endemic in rural areas in certain tropical and
subtropical regions. When it occurs in urban settings, trans-
mission of C. granulomatis typically is associated with a
history of multiple sexual partners. Untreated cases are
characterized by extensive scarring, often associated with
lymphatic obstruction and lymphedema (elephantiasis) of
Sexually Transmitted Diseases 677
the external genitalia. Culture of the organism is difficult,
and PCR-based assays are not widely available.
MORPHOLOGY
Granuloma inguinale begins as a raised, papular lesion involv-
ing the moist, stratified squamous epithelium of the genitalia.
The lesion eventually undergoes ulceration, accompanied by
the development of abundant granulation tissue, which takes
the form of a protuberant, soft, painless mass. As the lesion
enlarges, its borders become raised and indurated. Disfigur-
ing scars may develop in untreated cases, sometimes associ-
ated with formation of urethral, vulvar, or anal strictures.
Regional lymph nodes typically are spared or show only non-
specific reactive changes, in contrast with chancroid.
Microscopic examination of active lesions reveals marked
epithelial hyperplasia at the borders of the ulcer, sometimes
mimicking carcinoma (pseudoepitheliomatous hyper-
plasia). A mixture of neutrophils and mononuclear inflam-
matory cells is present at the base of the ulcer and beneath
the surrounding epithelium. The organisms are demonstrable
in Giemsa-stained smears of the exudate as minute coccoba-
cilli within vacuoles in macrophages (Donovan bodies). Silver
stains (e.g., the Warthin-Starry stain) also may be used to
demonstrate the organism.
S U M M A RY
Lymphogranuloma Venereum, Chancroid,
and Granuloma Inguinale
• LGV is caused by C. trachomatis serotypes that are distinct
from those that cause NGU. LGV is associated with
urethritis, ulcerative genital lesions, lymphadenopathy,
and involvement of the rectum. The lesions show both
acute and chronic inflammation; they progress to fibrosis,
with consequent lymphedema and formation of rectal
strictures.
• H. ducreyi infection causes an acute painful ulcerative
genital infection called chancroid. Inguinal node involve-
ment occurs in many cases and leads to their enlargement
and ulceration. Ulcers show a superficial area of acute
inflammation and necrosis, with an underlying zone of
granulation tissue and mononuclear infiltrate. Diagnosis is
possible by culture of the organism.
• Granuloma inguinale is a chronic fibrosing STD caused by
C. granulomatis. The initial papular lesion on the genitalia
expands and ulcerates, with formation of urethral, vulvar,
or anal strictures in some cases. Microscopic examination
reveals granulation tissue and intense epithelial hyperpla-
sia that can mimic the histologic pattern in squamous cell
carcinoma. Organisms are visible as small intracellular
coccobacilli within vacuolated macrophages (Donovan
bodies).
Trichomoniasis
T. vaginalis is a sexually transmitted protozoan that is a
frequent cause of vaginitis. The trophozoite form adheres
to the mucosa, where it causes superficial lesions. In
females, T. vaginalis infection often is associated with loss