Dysplasia

The role of dysplasia in the pathological process

In pathological anatomy, the development of dysplastic changes is often considered an outcome of prolonged tissue damage. Classical morphogenesis can be traced using the development of chronic obstructive pulmonary disease (COPD) as an example. The pathological chain includes the following stages:

1. Damage and desquamation of the normal ciliated epithelium.
2. Hyperplasia of cellular elements.
3. Metaplasia (transition to mucous or squamous form).
4. Development of dysplasia against the background of altered epithelium.

Similar foci of dysplasia and squamous metaplasia are also found in the lung tissue in late stages of idiopathic fibrosing alveolitis (in usual interstitial pneumonia). In gynecological practice, the detection of cervical dysplasia is critically important, as this process is closely associated with the development of preinvasive cancer.

Metaplasia as a preceding process

Dysplasia is often preceded by metaplasia—the replacement of one type of specialized tissue by another. Several epithelial variants of this process are distinguished:

• Squamous metaplasia: replacement of columnar, ciliated, or transitional epithelium with stratified squamous epithelium (sometimes with keratinization). It occurs in the urinary bladder in chronic cystitis, in the bronchi in bronchitis and COPD, and in the cervical canal in gonococcal infection.
• Glandular (columnar) metaplasia: the appearance of glandular epithelium, for example, in the urinary bladder (mentioned in the grading of transitional cell carcinoma).
• Gastric metaplasia: the formation of gastric-type foveolar epithelium in the duodenum against the background of chronic duodenitis.
• Intestinal metaplasia: the appearance of enterocytes with a brush border, goblet cells, and Paneth cells in atypical locations. It is observed in the stomach in atrophic gastritis and in the esophagus in Barrett's esophagus (replacement of stratified epithelium above the Z-line). It can be complete (type I) and incomplete (type II, predominantly mucin-producing).

There is also mesenchymal metaplasia, in which connective tissue transforms into bone tissue (e.g., osteogenesis in atherosclerotic plaques or tendons).

Types of biopsy for the diagnosis of tissue alterations

Various methods of material collection are used to detect dysplasia, metaplasia, and tumor growth:

• Excisional biopsy — complete removal of a lesion or tissue area within healthy margins.
• Incisional biopsy — taking only a part of the altered tissue.
• Targeted biopsy — collection of material from a specific pathological focus under visual (hysteroscopy, colposcopy, laparoscopy) or radiological (ultrasound, CT) guidance.
• Puncture and fine-needle (aspiration) biopsy — obtaining cells using a needle. It is used, among other things, in a "blind" manner (e.g., in liver biopsy).
• Core needle biopsy — extraction of a tissue core using a special needle (bone marrow, breast, and prostate glands).
• Step-section biopsy — repeated tissue sampling when there is a high risk of missing an occult process (e.g., with infiltrative growth in the esophagus).

Marginal biopsy is sometimes considered uninformative due to the inability to assess the overall tissue angioarchitecture/framework, whereas for skin examination, a full-thickness biopsy is preferred, as simple scrapings often yield false results.

Features of biopsy in various organs

The technique of tissue collection is adapted to the specific organ and clinical task:

1. Gynecology: targeted and excisional biopsy of the cervix are critically important for the histological confirmation of dysplasia and the exclusion of malignant tumors.
2. Liver: ultrasound-guided, laparoscopic, or blind needle biopsy is used to differentiate hepatitis and cirrhosis, search for viral markers, and signs of portal hypertension.
3. Myocardium: the procedure is performed strictly in the presence of a justified diagnostic hypothesis (e.g., in suspected dilated or inflammatory cardiomyopathy), often using electron microscopy.
4. Kidneys: biopsy combined with imaging helps confirm the diagnosis (e.g., IgA nephropathy) and assess the scale of parenchymal damage.

Class and exam questions

What else to study on this topic

• Histological grading of transitional cell carcinoma of the urinary bladder
• Morphogenesis of chronic obstructive pulmonary disease (COPD)
• Morphological types of liver cirrhosis (micronodular, macronodular)
• Pathological anatomy of Barrett's esophagus
• Diagnostic criteria for IgA nephropathy

Other topics in the "Additional Topics" section

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.