Generality
Squamous metaplasia is the conversion of a monolayer mucosal and / or glandular epithelium into a multilayered squamous epithelium.
In humans, the main examples of squamous metaplasia involve the bladder and cervix.
Associated with various factors, including cigarette smoking, hormonal changes and irritative phenomena, squamous metaplasia is a completely asymptomatic phenomenon, the identification of which requires specific tests such as endoscopy, cytological examinations and tissue biopsy.
Review of the medical-histological concept of metaplasia
In medical-histological language, " metaplasia " indicates the conversion of a healthy adult cell from a certain cellular typology to another cellular typology, all without undergoing any transformation in a neoplastic sense.
Extending this definition to epithelia, metaplasia is when a certain healthy epithelium changes its appearance and turns into another epithelium of completely different appearance, while remaining a healthy entity.
Under certain conditions, metaplasia is potentially reversible ; in other words, if certain circumstances are met, the cells subject to metaplasia can return to be those that were originally.
What is squamous metaplasia
Squamous metaplasia is the conversion of a monolayer mucosal and / or glandular epithelium into a multilayered squamous epithelium .
To understand:
- A monostratified mucous and / or glandular epithelium is an epithelium with secretory properties, consisting of a single layer of cells; "Mucous" and "glandular" refer to the secretory properties, while "monostratified" to the arrangement in a single layer of the cells constituting the epithelium.
- A multi-layered squamous epithelium, on the other hand, is an epithelium composed of several overlapping layers of flat cells; "Scaly" refers to flat cells, while "multi-layered" refers to the arrangement of cells forming the epithelium in several overlapping layers.
In light of what has been said so far, therefore, squamous metaplasia is the process that leads to an epithelium formed by a single layer of cells with secretory properties to assume the characteristics of an epithelium consisting of several overlapping layers of flat cells.
Is squamous metaplasia dangerous?
Although the term "meta" refers to metastases (ie the cells that a malignant tumor disseminates to the body) and the word "plasia" suggests a neoplasm, squamous metaplasia can not be identified with a tumor, nor benign nor much less malignant.
Once this important aspect has been clarified, another must be specified: if it is true that squamous metaplasia is not a neoplasm, it is equally true that squamous metaplasia can represent, in some rare circumstances, the very first step of a future tumor process (in other words, it is as if squamous metaplasia represented a sort of factor favoring the formation of a neoplasm).
When squamous metaplasia is at the origin of a tumor process, it is in effect a precancerous condition .
Important
Squamous metaplasia is a histological change that is almost always harmless and often reversible.
Only in very rare cases can it develop into a serious pathology and, when this happens, it is somewhat slow in its transformation work, which facilitates the early diagnosis of ongoing changes.
Where does squamous metaplasia usually occur?
Although theoretically a mucous and / or monostratified glandular epithelium can take place in any organ, squamous metaplasia is limited to the bladder and, in women only, the uterine cervix .
Of these two potential sites of squamous metaplasia, the most important, as far as the attention that is aroused in the general population, is without a doubt the uterine cervix, which is why from now on in this article they will always find a small information space related to squamous metaplasia of the cervix (or cervical squamous metaplasia ).
Causes
Currently, the causes of squamous metaplasia are a mystery; however, doctors have observed that factors such as:
- Cigarette smoke ;
- Stress ;
- Irritative phenomena or inflammatory processes . Statistics show that many cases of squamous metaplasia are associated with the presence of irritation or inflammation in the affected epithelium;
- The hormonal changes that, in women, characterize puberty, pregnancy and the post-partum phase. For quite obvious reasons, this favoring factor refers exclusively to the squamous metaplasia of the uterine cervix;
- Vitamin D deficiency or vitamin D overdose .
When is squamous metaplasia of the cervix more frequent?
In women, the phenomenon of cervical squamous metaplasia is more frequent during puberty, during a pregnancy and in the period immediately following birth.
This particular association confirms what was said previously about the favoring action that hormonal changes would have against the phenomena of squamous metaplasia of the uterine cervix (puberty, pregnancy and postpartum period are in fact phases of a woman's life characterized by substantial changes in hormone levels).
Epidemiology of cervical squamous metaplasia
According to reliable statistical studies, cervical squamous metaplasia
- Significantly affects both young women (girls) and adult women;
- It could be present in more than 50% of adult women (the conditional is a must, because it is a presumed datum, devoid of diagnostic findings);
- It has no preference for a particular ethnic or racial group.
Symptoms and complications
Squamous metaplasia is a completely asymptomatic phenomenon, so those who are subject to it do not manifest any symptom or sign connected.
It is due to the lack of symptoms, on the part of squamous metaplasia, that the identification of the latter, in a person, occurs very often by chance, during diagnostic examinations performed for other reasons.
Complications
The most relevant complication of squamous metaplasia is the formation - starting from a cell of the epithelium victim of the conversion process to a completely different epithelium - of a malignant tumor (or malign neoplasm).
As stated, the possibility of a malignant evolution of squamous metaplasia is, fortunately (given the not inconsiderable frequency with which squamous metaplasia takes place), a very rare event.
The malignant evolution of an episode of squamous metaplasia is often associated with the appearance of symptoms and signs, which clearly depend on the organ concerned.
COMPLICATIONS OF CERAMIC SQUAMOSA METAPLASIA
In the specific case of cervical squamous metaplasia, the possible complications of this medical condition are:
- A major vulnerability, by the affected epithelium, to Human Papilloma Virus (or HPV ) infections. HPV is the infectious agent infamous for being one of the main risk factors for cervical cancer (or cervical cancer );
- The malignant evolution of a cell of the epithelium subject to squamous metaplasia, with the consequent formation of a tumor on the cervix.
Diagnosis
The diagnosis of squamous metaplasia may require: a detailed medical history, a thorough physical examination, endoscopic instrumental tests, cytological tests of various kinds and a tissue biopsy .
Diagnosis of cervical squamous metaplasia: what tests does it require?
An accurate diagnosis of episodes of cervical squamous metaplasia could be based on:
- Information from the history and physical examination;
- The cytological findings of the Pap test;
- Colposcopy;
- Cervical biopsy.
Table. Microscopic classification (ie based on microscopic investigations) of cervical squamous metaplasia. According to this classification, there are three types of squamous metaplasia of the uterine cervix: mature squamous metaplasia, immature squamous metaplasia and atypical squamous metaplasia.
The box below shows the characteristics of these three types of cervical squamous metaplasia just mentioned.
| Type of cervical squamous metaplasia | Features |
Mature squamous metaplasia | The "new" squamous epithelium is well formed and mature. Normally it characterizes the conclusion of the epithelial conversion process ("mature" refers to this). |
Immature squamous metaplasia | It represents the moment in which the epithelial conversion process is in progress ("immature" refers precisely to this). The cytological tests performed during this phase of the conversion show that the epithelium is, in part, still in the possession of glands and, in part, made up of squamous cells. |
Atypical squamous metaplasia | At cytological examinations, the squamous epithelium has cells with abnormal nuclei and with unusual mitotic activity. These abnormal behaviors could be the result of an HPV infection or an onset tumor transformation process. For obvious reasons, it is the most worrying type of cervical squamous metaplasia and the one to keep under control with periodic diagnostic tests. |
What to do in the presence of cervical squamous metaplasia?
The diagnostic finding of a cervical squamous metaplasia deserves the right consideration: it must not arouse excessive worries, but at the same time it must not even be overlooked.
In such circumstances, therefore, the best thing to do is to undergo the periodic checks foreseen, rely on a doctor specialized in the genital apparatus of women ( gynecologist ) and follow its instructions and advice.
Therapy
In general, squamous metaplasia does not require any special treatment or medical intervention, unless the diagnostic tests carried out reveal, by the mutated epithelium, some disturbing characteristic (eg, behavior similar to that of cancer cells) or the condition in question there are no particular symptoms and / or signs (these, in fact, could be the consequence of a malign evolution of squamous metaplasia).
Prevention
Preventing squamous metaplasia is impossible and, given the reduced danger of the aforementioned condition, the search for an effective prevention method is not among the main objectives of the doctors.
Cervical squamous metaplasia and prevention of HPV infections
For women susceptible to HPV and with cervical squamous metaplasia, experts recommend the implementation of all those precautions that reduce the risk of contracting the aforementioned viral agent.
Prognosis
Except in rare circumstances, the prognosis in the case of squamous metaplasia is excellent.
Prognosis of cervical squamous metaplasia
The only cases of cervical squamous metaplasia that could have a negative prognosis are those included in the typology known as atypical squamous metaplasia.
