Squamous (squamous) metaplasia is a non-cancerous change in the epithelium of the internal organs, which is a protective reaction of the body to the influence of unfavorable factors. Metaplasia is a pathological process in which a single-layered cylindrical, prismatic or cubic epithelium is replaced by more hardy cells of multilayered planar epithelium, with or without keratinization. Most often squamous cell metaplasia affects the lung epithelium (especially in smokers) and the cervix, but can also affect the mucosa of the bladder, intestines, internal glands.
The mechanism of squamous cell metaplasia
The development of metaplasia, we consider the example of the mucous cervix, where the replacement of the cylindrical epithelium is flat. The metaplastic flat epithelium develops not from the basic mature cells, but from the underlying, the so-called reserve cells. That is, under the layer of the cylindrical epithelium, a layer of reserve cells is formed, which gradually grows. Gradually, the upper layer of the cylindrical epithelium is peeled off and its replacement occurs. Next comes the stage of immature squamous cell metaplasia, in which histological studies clearly show the boundaries of groups of reserve cells and form several layers of cells that are similar to the ordinary flat non-coronary epithelium.
At the stage of maturing squamous cell metaplasia, cells become more and more similar to the intermediate cells of the flat epithelium, and at the stage of mature metaplasia, the epithelium is indistinguishable from the natural surface layer of the flat epithelium.
Is squamous metaplasia dangerous?
Metaplasia is not a disease, but a variant of the organism's adaptation to physiological or pathological stress factors. In connection with this specific feature, squamous cell metaplasia does not and is diagnosed only in laboratory studies, due to the detection of cells of the flat epithelium in smears, sputum, other research material or histological examination of tissues.
Most often, metaplasia is formed against the background of chronic inflammatory processes, as well as with adverse external effects (smoking, working in an unfavorable environment, etc.). Although in itself it is a benign, reversible process, but long-term persistence of adverse factors or the absence of treatment for a disease that provoked changes, may further lead to dysplasia and a precancerous condition.
The causes and treatment of squamous metaplasia
The most common is squamous metaplasia of the cervix. It can be a reaction to:
- chronic inflammatory process;
- erosion of the cervix ;
- hormonal disorders;
- infectious diseases.
Squamous cell lung metaplasia is most often caused by smoking, but can also be triggered by chronic diseases (bronchitis, asthma , etc.). Metaplasia of the bladder is caused by inflammatory processes, and in the first place among the causes is cystitis.
Since squamous cell metaplasia is a variant of the adaptive reaction of the body, it does not require specific treatment. After curing the underlying disease or cessation of the impact on the body of the stress factor, after a while the epithelium itself returns to normal. For example, to treat squamous cell metaplasia of bronchial epithelium, provoked by smoking, it is enough to abandon this habit, and the rest of the treatment will be symptomatic.