This document discusses several types of metaplasia and dysplasia: - Metaplasia is the replacement of one type of epithelium with another, such as squamous metaplasia in the lungs of smokers. Dysplasia refers to abnormal cell growth. - Examples of metaplasia include intestinal metaplasia of the stomach and Barrett's esophagus. Squamous metaplasia can occur in the lungs, bladder, and breasts. - Dysplasia can be developmental, like hip dysplasia, or involve abnormal cell growth, such as cervical or myelodysplastic dysplasias which can progress to cancer. Both conditions represent changes to normal cell growth in response to injury

1. Yuzbasheva Nihal

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

9. • 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

10. 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.

13. • 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.

14. • 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.

15. • 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.

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

18. <- Normal
Abnormal ->
• Developmental dysplasia - Dysplasia in children is usually
developmental, and can be present as early as a child's fetal
stages:
1. 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.

19. 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.

20. • 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:
1. 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.

21. 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.

23. 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.

24. 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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