Metaplasia & Dysplasia

Metaplasia & Dysplasia
- Some examples of metaplasia and dysplasia

1. Yuzbasheva Nihal Metaplasia & Dysplasia

2. Metaplasia :  the exchange of normal epithelium for another type of epithelium. Metaplasia is reversible when the stimulus for it is taken away .

3. Metaplasia is thought to arise by reprogramming of stem cells to differentiate along a new pathway rather than a phenotypic change ( transdifferentiation ) of already differentiated cells.

4. Epithelial metaplasia – squamous change that occurs in the respiratory epithelium of habitual cigarette smokers. The normal ciliated columnar epithelial cells of the trachea and bronchi are focally or widely replaced by stratified squamous epithelial cells. The rugged stratified squamous epithelium may be able to survive the noxious chemicals in cigarette smoke that the more fragile specialized epithelium would not tolerate .

5. Although the metaplastic squamous epithelium has survival advantages, important protective mechanisms are lost, such as mucus secretion and ciliary clearance of particulate matter. Squamous metaplasia of the respiratory epithelium often coexists with lung cancers composed of malignant squamous cells. It is thought that cigarette smoking initially causes squamous metaplasia , and cancers arise later in some of these altered foci. Since vitamin A is essential for normal epithelial differentiation, its deficiency may also induce squamous metaplasia in the respiratory  epithelium. 

6. Intestinal Metaplasia - progesive replacement of gastric mucosa by epithelium having the light and electronic microscopic features of intestinal epithelium of either small or large bowel type, including goblet cells, absorptive cells, paneth cells and variety of endocrine cells

7. In cases where tumor produces acidic mucins it is possible that the tumor arose from the areas of intestinal metaplasia

8. A family history of a first-degree relative with gastric cancer was associated with a significantly increased risk of having gastric intestinal ietaplasia on univariate (P<0.01) and multivariate analysis (OR 8.51, 95% CI: 1.52-40.22, P=0.018). Neither tobacco use nor alcohol use were associated with gastric intestinal metaplasia on univariate analysis. Furthermore, neither proton-pump inhibitors nor H2-blockers were associated with finding gastric intestinal metaplasia on gastric biopsies on univariate analysis 

9. This biopsy of the lower esophagus in a patient with chronic gastroesophageal reflux disease (GERD) shows  columnar metaplasia  (Barrett's esophagus), and the goblet cells are typical of an intestinal type of epithelium.  Squamous epithelium   typical of the normal esophagus appears at the right.

10. Urothelial Squamous Metaplasia - The urothelium lining the urinary bladder can undergo squamous metaplasia due to chronic injury from urinary stones and from granulomatous chronic inflammation associated with an infection due the worm Schistosoma hematobium . With time these can progress to squamous cell carcinoma.

11. PERIDUCTAL MASTITIS ( Squamous metaplasia of lactiferous duct) - Women , and sometimes men, present with a painful erythematous subareolar mass that clinically appears to be an infectious process. More than 90% of the afflicted are smokers. This condition is not associated with lactation, a specific reproductive history, or age. In recurrent cases, a fistula tract often tunnels under the smooth muscle of the nipple and opens onto the skin at the edge of the areola. Many women with this condition have an inverted nipple, most likely as a secondary effect of the underlying inflammation. The strong association with cigarette smoking is intriguing. It has been suggested that the vitamin A deficiency associated with smoking or toxic substances in tobacco smoke alter the differentiation of the ductal epithelium.

12. The key histologic feature is keratinizing squamous metaplasia of the nipple ducts. Keratin shed from these cells plugs the ductal system, causing dilation and eventually rupture of the duct. An intense chronic and granulomatous inflammatory response develops once keratin spills into the surrounding periductal tissue . Sometimes a secondary bacterial infection supervenes and causes acute inflammation.  

13. Dysplasia is a condition marked by abnormal cells that can lead to enlarged tissue or pre-cancerous cells.

14. <- Normal Abnormal -> Developmental dysplasia - Dysplasia in children is usually developmental, and can be present as early as a child's fetal stages : Hip dysplasia – (developmental dysplasia of the hip (DDH)) Hip dysplasia either means that the hip joint is in the wrong shape or that the hip socket is not in the correct place to cover and support the leg bone. This causes more wear and tear on every part of the hip joint.

15. 2. Skeletal dysplasia - Skeletal dysplasia is responsible for the disorders known as dwarfism, brittle-bone disease, and cherubism . There are over 350 disorders of the skeleton which are classed as dysplasia. They are caused by a genetic mutation, and can generally be diagnosed in a fetus or infant. 3. Ectodermal dysplasia - there are more than 150 types of ectodermal dysplasia. Certain types of dysplasia may be seen at birth, while others may take years to be diagnosed correctly. These dysplasias affect the skin, hair, nails, and sweat glands. Ectodermal dysplasias are genetic, meaning they can be passed on to children. They are caused by genetic mutations.

16. Dysplasia as abnormal growth - When found in adults, dysplasia usually refers to the abnormal growth of cells or tissues. When these cells continue to grow, they can create tumors. Dysplasia can occur on any number of tissues in the body, but is most commonly found in adults in a few different forms: Hip dysplasia in adults - Adults who have been diagnosed with hip dysplasia have likely had undiagnosed dysplasia since childhood. The International Hip Dysplasia Institute estimate 35,000 hip replacements each year are due to hip dysplasia. Bilateral hip dysplasia in a 29 year old female.

17. 2. Cervical dysplasia - Cervical dysplasia gets its name from abnormal cells on the surface of the cervix. Cervical dysplasia is divided into two categories: - Low-grade cervical dysplasia - progresses slowly and often gets better on its own - High-grade cervical dysplasia -  can lead to cervical cancer.

18. 3. Myelodysplastic syndromes (MDS) - type of dysplasia in the marrow of the bones. This abnormal growth can mean that the bone marrow does not produce enough healthy blood cells for normal bodily functions. According to the MDS Foundation, MDS usually occurs in older adults. While some people affected with MDS may be young, most cases involve people older than 65.

19. Refractory cytopenia with multilineage dysplasia (RCMD). Bone marrow biopsy (H & E stain). The biopsy demonstrates erythroid hyperplasia. Immature erythroid precursors (arrows) have round to oval vesicular nuclei, a prominent, comma-shaped nucleolus that often is close to the nuclear membrane, and a rim of amphophilic cytoplasm. Erythroid precursors that are more mature (double arrows) have homogenous, darkly-stained nuclei.

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