squamous cell carcinoma evolves through a series of preinvasive lesions,
known as dysplasias or intraepithelial neoplasias.
Esophagus has its own
unique types which may differ from those occurring in other squamous sites,
such as cervix and skin.
According to some
studies these precursor lesions were more common in high cancer-risk areas
than in the low-risk areas.
There is an increased proliferation of cells in
the upper layers of the esophageal squamous epithelium in people who live in
grades of dysplasia are usually described as partial-thickness
abnormalities, involving less than half of the epithelial thickness and
higher grades as involving more than half, separating grades of dysplasia on
the basis of level of involvement is not always reliable.
one grade of dysplasia from another is frequently difficult, since there are
no clear lines of demarcation.
As a result, even with a two-grade system
that includes low and high grades, there are occasional dysplasias that seem
to be borderline or intermediate between the two grades.
In the future, all
intraepithelial proliferations might be grouped into a spectrum that could
be designated esophageal intraepithelial neoplasia (EIN), comparable to the
terms in use for the uterine cervix, the vagina, and the vulva, or into a
two-grade dysplasia system comparable to that used in ulcerative colitis.
The lesion is visible endoscopically and is
Microscopic features :
The preinvasive lesions, or dysplasias, contain abnormal epithelia which
vary from that closely resembling the normal squamous mucosa to epithelium
so disorganized that its malignant cytologic and architectural features are
There are atypical squamous cells with disorganized architecture and abnormal
differentiation within the epithelium.
These features are obvious in high
The nuclei are larger and more hyperchromatic than normal,and there is increased mitotic activity.
The lower grades of dysplasia have a larger component of mature-appearing squamous cells, some
of which may be keratinized, and the abnormal cells are often limited to the
lower half of the epithelium .
The highest grade of dysplasia is squamous cell carcinoma in situ or
The histological variants:
1.Basal squamous dysplasia 2.Pagetoid
The lesion may present as a single lesion in
the absence of invasive tumour or as a peripheral component in the backround
squamous mucosa , with invasive squamous carcinoma.