Slide 2 Slide 3 Slide 4 Periapical Granuloma Chronic
inflammatory reaction in response to a pulpal infection with
bacteria. All we can see here are tiny blue dots sprinkled across
the entire tissue section. As we shall see next, These are blood
leukocytes that have migrated out of vessels into tissue to form
what is known as an inflammatory cell infiltrate. -Granulation
tissue (fibrovascular) -Mononuclear inflammatory cell infiltrate
-chronic inflammation Slide 5 Periapical Granuloma Here we can see
some small vessels (arrow) and only faint, immature collagen in the
background (pink). The dots sprinkled all around are leukocytes; at
this magnification, we cant definitively identify what types of
whites cells they are. -Granulation tissue (fibrovascular)
-Mononuclear inflammatory cell infiltrate -chronic inflammation
Slide 6 Periapical Granuloma -Granulation tissue (fibrovascular)
-Mononuclear inflammatory cell infiltrate -chronic inflammation The
red arrows point to small round blue nuclei and represent
lymphocytes. The blue arrows designate plasma cells; you can see an
eccentric nucleous with a purple cytoplasm. Elsewhere in this view,
capillaries are present, eosinophilic (pink) collagen is in the
background and some of the more spindle shaped cells are
fibroblasts. Slide 7 Slide 8 PA Gran, Subacute Inflammation Notice
that the inflammatory cell infiltrate is somewhat different. The
background granulation tissue (fibrovascular element) remains
unchanged. In this photomicrograph one can identify: macrophages
(yellow arrow) plasma cells (blue) neutrophils or PMNs (green) This
combination is referred to as subacute inflammation (mononuclear
cells and granulocytes). What controls this response? The type of
micro-organism does. Certain microbes stimulate an acute response,
others a chronic one and yet others, a subacute inflammatory
response. Slide 9 Slide 10 Slide 11 Slide 12 Parulis, acute
inflammation This is a biopsy from a draining fistula or parulis
associated with an abscessed tooth. At this relatively low
magnification one can see a virtural sea of leukocytes and numerous
capillaries (red arrows). The granulation tissue here shows no
collagen fibers..only vessels. Slide 13 Abscess/Parulis This higher
magnification discloses a few vessels, some mononuclear cells (very
few) and mostly sheets of neutrophiles or PMNs. This is what is
termed acute inflammation and when localized under the gingiva it
is a submucosal abscess or parulis. In such an instance, the
pyogenic bacteria coming out of the necrotic pulp have invaded
through bone and out the cortex. Slide 14 Slide 15 Apical
Periodontal Cyst, low In some endodontic infections, not only is
there an inflammatory response, but the Rests of Malassez in the
apical PDL are stimulated by inflammatory cytokines and growth
factors secreted by leukocytes to proliforate. As these epithelial
cells increase in size, they become necrotic in the center to
create a stratified squamous epithelial lined cavity or cyst. In
this low power photomicrograph, the root tips are evident at the
top of the view and below is a collapsed cavity. At this power one
cannot see the epithelial lining Slide 16 Slide 17 Periapical Cyst,
Medium In this view, one sees the root surface on the right (we
cannot actually see the necrotic root canal in this section) To the
left is an epithelial lining that still shows proliferation with
cords and strands of anastomosing cells. Interposed between the
cyst and the root is fibrous connective tissue, a tissue that
matured from preexisting granulation tissue. Adjacent to the cyst
lining are numerous leukocytes. Slide 18 Slide 19 APC, Thin Wall
This photomicrograph is a low power view of a large apical cyst
where one can observe the distended cyst wall, epithelial lining
and a lumen filled with amorphous eosinophilic (pink) material that
represents the cyst contents of proteinaceous coagulated fluid.
Slide 20 Slide 21 Inflammation in Wall This is a higher
magnification of the previous image showing the stratified squamous
lining on the left, fibrous connective tissue wall in the center,
and on the outer edge is an inflammatory cell infiltrate
represented by mononuclear leukocytes, mostly lymphocytes (Chronic
inflammation). Slide 22 Slide 23 Cholesterol Cleft, Multinucleated
Giant Cells In some apical inflammatory lesions, and for reasons
not understood, cholesterol accumulates in the fibrous and
granulations tissues. The cholesterol crystallizes into surf-board
shaped clear cavities. They are clear because the processing of the
tissues for histology uses lipid solvents so all we see are ghosts
of the material. Cholesterol out in the tissues acts as a foreign
body and one then sees fused macrophages or multinucleated foreign
body type giant cells stretched around the clefts in the process of
attempted (in vain we think) phagocytosis. Slide 24 Slide 25
Pyogenic Granuloma, low mag Now we will take a look at inflammation
out in the soft tissues of the gingiva and periodontium. When food
particles, popcorn kernals or perhaps even calculus become
entrapped in the gingival sulcus, they act as an irritant and
stimulate an overzealous proliferation of granulation tissue
accompanied by inflammation. This low power photomicrograph was
obtained from a gingival mass arising in the interdental papilla.
There is an epithelial layer over the top and the mass is composed
of granulation tissue. Slide 26 Slide 27 Pyogenic Granuloma, medium
In this medium power view, we can see an epithelial layer on the
left and on the right, the mucosal epithelium is lost. This is
referred to as ulceration and the surface is represented by a
fibrin clot with entrapped neutrophils. The mass is represented by
numerous proliferating blood vessels with intervening loose fibrous
tissue - an excellent example of very vascular granulation tissue.
Leukocytes are distributed throughout. Slide 28 Slide 29 Pyogenic
Granuloma, high This high magnification shows the dilated vascular
channels lined by endothelial cells and interposed loose fibrous
tissue infiltrated with neutrophils. The term pyogenic implies an
infectious etiology. It is not. The pyogenic granuloma is a
reactive proliferation; reacting to irritation, not infection. This
then is an example of the host inflammatory response forming in
response to injury. Slide 30 Slide 31 Mucous Retention Phenomenon
Lower Lip Slide 32 Slide 33 Mucous Escape Reaction This low power
view of a mucocele shows a layer of surface epithelium and an
underlying cystic mass filled with purple fluid (mucin). Minor
salivary gland lobules are evident on the lateroinferior margin.
The mucocele forms as a consequence of ductal severage with escape
of secreted mucins into the surrounding connective tissues. Slide
34 Slide 35 Mucocele Wall When the mucous escapes, it pools and is
walled off by granulation tissue. In this medium power view, one
can observe the mucin on the top, granulation tissue with
underlying dense collagenous tissue in the center and minor
salivary glands along the bottom. Slide 36 Slide 37 Phagocytosis of
Mucin At the interface between the granulation tissue wall and the
pooled mucin, macrophages can be seen, attempting to phagocytize
the mucin. Their nuclei are round and they have a significant
amount of pink cytoplasm that has a bubbly or foamy appearance
owing to the mucins that have been ingested by these cells Slide 38
Slide 39 Inflammatory Fibrous Hyperplasia Denture Associated This
low magnification specimen shows a lobulated mass represented by a
partial covering with epithelium and a massive proliferation of
fibrous tissue below. Collections of minor salivary tissue were
included in the biopsy. Slide 40 Slide 41 Inflammatory Fibrous
Hyperplasia This low magnification specimen shows a lobulated mass
represented by a partial covering with epithelium and a massive
proliferation of fibrous tissue below. Collections of minor
salivary tissue were included in the biopsy. Slide 42 Slide 43
Epithelial and Fibrous Hyperplasia At medium power, it can be seen
that the surface epithelium is thickened or hyperplastic, a
response to trauma from the denture flange. Below is dense mature
collagenous connective tissue. This connective tissue appears
relatively normal and is traversed by capillaries. Under the
epithelium are a few scattered inflammatory cells. Slide 44 Slide
45 Chronic Sclerosing Sialadenitis The salivary tissues deep in the
specimen have also been traumatized and their secretions have been
blocked leading to degeneration of the acini. As the acini
disappear from apoptosis and necrosis (forms of cell death),
inflammatory cells infiltrate and phagocytize the necrotic cells.
This is inflammation in response to injury. Slide 46 Slide 47
Chronic Sclerosing Sialadenitis In this higher magnification, one
can see very few remaining acini, although the ducts are more
resistant to the trauma and the effects of obstruction. Ductal
structures remain in the absence of acini. The normal tissues are
then replaced by mononuclear inflammatory cells and the granulation
tissue matures into dense fibrous scar-like tissue. Sclerosis means
fibrosis or scar formation. Slide 48 Slide 49 Tuberculosis Ulcer
Tongue Slide 50 Slide 51 Granulomatous Inflammation Specific
granulomatous inflammation is a special form of chronic
inflammation that is induced be certain microorganisms,
Mycobacterium tuberculosum being the classic example, although
invasive fungal organisms also cause this type of inflammation. By
definition, chronic granulomatous inflammation is a chronic
inflammatory reaction in which one sees collections of granulation
tissue (granulomas), mononuclear inflammatory cells (lymphocytes,
plasma cells, macrophages) and most importantly, multinucleated
giant cells as seen here. Slide 52 Slide 53 Tuberculous Granuloma
In this section of chronic granulomatous inflammation, a collection
of multinucleated giant cells can be seen in the background of
granulation tissue and other leukocytes. These giant cells form by
fusion of macrophages to create monster phagocytic cells. Certain
glycoproteins on the cell wall of specific microorganisms play a
role in this cell fusion process. Slide 54 Slide 55 Langhans Giant
Cell In TB, the giant cells have a distinctive appearance. The
nuclei are arranged around the periphery, a wreath-like
configuration, and a smooth pink cytoplasm lies in the center of
the cell. These are Langhans Giant cells. The red arrows point to
individual macrophages from which the giant cells form. Blue arrows
point to lymphocytes out in the granulation tissue. In order to
actually see the mycobacteria within the giant cell, we would have
to apply an acid-fast stain. Slide 56 Slide 57 Foreign Body Giant
Cells Here are photomics showing suture material and multinucleated
giant cells as well as surrounding individual macrophages. Note
that the nuclei are dispersed throughout the cytoplasm unlike the
Langhans cells of TB. This entire focus is called a foreign body
granuloma. Slide 58 Slide 59 Foreign Body Reaction Gut and nylon
suture are resorbable. In this section of mouse liver, gut sutures
were placed and after three days, we can see the yellow filaments
of the suture material and surrounding inflammatory cells. Even at
this magnification, it is easy to see the giant cell reaction in
the upper left.
