Adenocarcinoma in situ of the cervix originates from reserve cells underlying columnar epithelium. Over 60% of these lesions are associated with a squamous epithelial lesion of the cervix, ranging anywhere from a condyloma to a more advanced lesion such as an invasive squamous cell carcinoma. It comprises 5 to 8% of all cervical cancers.

Given that the cells are not always successfully collected by a retrieval instrument, the lesion is often difficult to diagnose. The lesion arises from endocervical epithelium, at the squamous columnar junction and at the times from a hidden gland whose entry has been replaced by squamous metaplasia. Furthermore, the cells are not recognized as atypical for a variety of reasons. For example, this lesion can be confined in an endocervical polyp and thus not accessible. In histological section, the delineation between normal epithelium and adenocarcinoma is not a gradual one but is abrupt. The diagnosis of adenocarcinoma in situ is based primarily on nuclear and architectural criteria.

Architectural Criteria:

The typical honeycomb arrangements of these aggregates of cells, lose their common aspect and become disorganized. The cells tend to overlap and become crowded. In the periphery of the sheet, one can observe pseudostratification of the nuclei. There are other criteria which are considered typical of a cervical adenocarcinoma in situ. For example, " feathering " in which the glandular cells are very elongated, with scant and frayed cytoplasm and the nuclei give the impression of projecting out of the aggregate, resembling the outstretched wings of a bird.

The other typical arrangement is the rosette formation. These rosettes consist of approximately ten cells or so, cohesive at the base area of the cytoplasm, the nuclei eccentrically located, with the typical pseudostratification of the nuclei.

Nuclear Criteria:

The criteria consist of slight nuclear pleomorphism, somewhat granular chromatin and occasional abnormal mitosis. The nuclear borders may be slightly irregular and thick but not in a way too remarkable. The nucleoli are usually small in contrast to a poorly differentiated adenocarcinoma where they can appear as macronucleoli. Mucin secretion tends to be absent. Frequently, the nuclear atypia of cervical adenocarcinoma in situ are not as impressive as those found in cytological atypias of the squamous epithelial type.

In invasive adenocarcinoma, there is marked variation of the size and shape of the nucleus. The chromatin is more irregularly distributed. The cytoplasm is more abundant. There are macronucleoli. There is a necrotic and bloody background. The progression from adenocarcinoma in situ to invasive adenocarcinoma , takes several years. There are risks of errors in the diagnostic features of adenocarcinoma in situ of the cervix, the most common of which are it's subtle atypias, the overlapping features of this lesion with those ciliated benign glandular cells, originating from a superior segment of the cervix or those cells from the inferior segment of the endometrium. Adenocarcinoma in situ cells can also be mistaken for an abnormal high grade squamous epithelial lesion. It can also be difficult to differentiate between reactive glandular cells due to an inflammatory, reparative or degenerative process, with the features of those from adenocarcinoma in situ. Futhermore cellular detail can be obscured by blood or leukocytes. At times, atypical cells may appear pale due to technical error in the staining or preparation of the specimen. It is thus of great importance to carefully analyse the cellular details at high magnification. The diagnosis must be based on a number of criteria rather than any one, single criteria.

Notwithstanding all our efforts, it occurs, unfortunately, that the more common squamous differentiation captures our attention, resulting in the oversight of an obvious glandular differentiation. One must keep in mind the possibility of the presence of two differentiations.

-38 year-old woman.

Pour en savoir plus:

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