A study of the incidence and histogenesis of endocervical metaplasia and intraepithelial carcinoma. Observations on 400 uteri removed for noncervical disease

Thin HSIL of the Cervix: Detecting a Variant of High-grade Squamous Intraepithelial Lesions With a p16INK4a Antibody

The WHO defines thin high-grade squamous intraepithelial lesions (HSIL) as a high-grade intraepithelial lesion of the cervix that is usually ≤9 cells thick. These lesions usually develop in early metaplastic squamous epithelium without anteceding low-grade squamous intraepithelial lesions (LSIL). The prevalence of thin HSIL is not well documented. We evaluated different characteristics of thin HSIL at time of treatment. We studied 25 formalin-fixed and paraffin-embedded conization specimens processed as step-serial sections. HSIL≤9 cells thick were classified as thin HSIL. HSIL≥10 cells thick were classified as classic HSIL. Immunohistochemical p16 staining was used to confirm lesions of thin HSIL. Overall, 19 (76%) specimens contained both thin HSIL and classic HSIL, 4 (16%) contained thin HSIL only, 1 (4%) contained classic-type HSIL only, and 1 (4%) contained thin HSIL and LSIL. Thin HSILs developed in both the columnar surface epithelium and deep cervical glandular epithelium. Most thin HSILs were 5 cells thick. All HSILs (thin and classic) were located inside the transformation zone and had a median horizontal extension of 8 mm (range, 0.3 to 21 mm). Our findings suggest that thin HSILs are frequent findings, that they coexist with classic HSIL, and preferably arise in the exposed parts of the transformation zone including the glandular crypts.

Origin and immunoescape of uterine cervical cancer

Human papillomavirus associated uterine cervical cancer is an important public health problem since it is classified as the fourth most common cancer in women worldwide with more than 500,000 recorded cases. This review is focused on where and why HPV infection induces cervical cancers and how this virus avoids the host immune response. Immunological therapeutic approaches are also addressed.

Early physiologic squamous metaplasia of the cervix: light and electron microscopic observations

A light and electron microscopic study was undertaken of the early phases of cervical squamous metaplasia. A study of areas of columnar epithelium with one row of subcolumnar cells revealed a spectrum of squamous differentiation ranging from cytologically undifferentiation to more characteristically basal type squamous cells. With increasing differentiation, squamous characteristics, such as tonofibrils and desmosomes, became qualitatively and quantitatively more evident in the cells. Ultrastructural examination also revealed cells in the subepithelial stroma with prominent basal lamina and hemidesmosome-like structures along the periphery. From a light and electron microscopic viewpoint, the most likely origin for the subcolumnar progenitor cells appears to be the subepithelial stromal cells. The resemblance of these subepithelial stromal cells to the subcolumnar cells in very early stages of metaplasia is often striking.

Noninvasive precursor lesions of adenocarcinoma and mixed adenosquamous carcinoma of the cervix uteri

It is postulated that squamous cell carcinoma, adenocarcinoma, and mixed adenosquamous cell carcinoma of the uterine cervix all have a common cell or origin, the subcolumnar reserve cell. The relative frequency with which the various types of carcinoma in situ are seen is in part explained by the ubiquitous nature of squamous metaplasia in the region of the transformation zone in women of reproductive age. It is suggested that squamous metaplasia is the soil on which most squamous carcinomas of the cervix evolve. The relatively low frequency with which adenocarcinoma and adenosquamous carcinoma in situ are encountered may also be dependent on their less accessible location in the endocervix.

[Electron microscopical investigations on the so-called reserve cells in the cylindrical epithelium of the human cervix uteri (author's transl)]

By electron microscopical investigations on the cylindrical epithelium of the human cervix uteri there can be shown that the regeneration of the endocervical epithelium takes place from bipotent reserve cells, which are of fetal origin, lying in the basal layer of the epithelium. These cells are able for mitosis even in postnatal life. The reserve cells differentiate if necessary to squamous cells or secretory cells by forming typical cell organelles. There is a discussion about the question whether the reserve cells are persisting elements from fetal life or whether the numeral balance of the endocervical epithelium is kept by permanent mitosis.

[The so-called "reserve cells" of the human cervical (author's transl)]

I. Basal cells occurring focally beneath the columnar epithelium of the endocervix are generally regarded as "reserve cells". Single "reserve cells" cannot be identified among the columnar epithelial cells. II. Single "reserve cells" would not be needed for the regeneration of the cervical mucosa, since the normal columnar, cells themselves are capable of undergoing mitotic division. During such mitoses the mitotic spindle is located above the regular row of nuclei, the axis of the spindle running parallel to the basement membrane and surface of the cell, so that the daughter cells separate in a horizontal direction. Consequently, the term "reserve cell" with its functional implication is misleading and should be replaced by a more descriptive term such as the "subcylindrical"cell. III. It seems that for development of focal groups of subcylindrical cells according to I the columnar cells must proliferate locally. That proliferation could occur with the axis of the mitotic spindle rotated 90 degrees to be perpendicular to the basement membrane. More likely, however, the columnar cells seem to undergo mitoses with their spindles parallel to the basement membrane and accumulate locally to form two layers. On further proliferation of the basal layer, with the mitotic spindles rotated 90 degrees to be perpendicular to the basement membrane and with desquamation of the overlying columnar cells, the than multilayered epithelium may differentiate by indirect metaplasia into squamous epithelium.