A quick and easy overview on blood pathology. Hope you find it helpful. #reference: Shafer's book of oral pathology, Davidson's, A.k jain #intro: preksha singh, BDS student #E-mail: preksha.srajput@gmail.com

1. DISEASES INVOLVING
BLOOD PLATELETS
Preksha singh
3rd yr
BDS

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Table of
Contents
2
1 Introduction
3 Thrombocythaemia
2 Thrombocytopenia
CONTENTS

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• These are small, colorless, non nucleated, spherical blood cells developing from
megakaryocyte.
• Has various receptors and cytoplasmic granules (dense and alpha granules) .
• Function : haemostasis, blood coagulation, phagocytic function, clot retraction.
• Normal count : 50,000 to 450,000 platelets per microliter of blood.
• Destruction : in spleen.
INTRODUCTION:
PLATELETS
Clotting factors PDGF
Stimulates wound healing repairs damaged blood vessels

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PLATELET DISORDERS:
01
Thrombocythaemia: increased platelet counts
Thrombocytopenia: decreased platelet counts
Thrombocytopathy: platelet dysfunction

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• Decreased peripheral blood platelet counts i.e. <150,000 cells/mm3.
Causes
Thrombocytopenia:
reduced production
increased destruction
increased sequestration in
spleen

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Thrombocytopenia:
1. Reduced production: infections, drugs, radiotherapy, vit. Deficiency, marrow failure.
2. Increased destruction : ITP, thrombotic microangiopathies, post transfusion purpura, HIT, DIC
3. Sequestration due to hypersplenism: cirrhosis, hepatic failure, malignancy, infectious
disease, sarcoidosis, etc.
Bleeding risk based on platelet count:
Platelet counts bleeding
50,000-150,000 Unexpected(unless platelets are
dysfunctional)
10,000-50,000 May follow trauma, surgery
<10,000 Spontaneous bleeding

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Purpura: A purplish discolouration of skin and mucous membrane due to the spontaneous
extravasation of blood.
Clinical features: purpuric haemorrhagic skin lesions.
1. spontaneous and profuse gingival bleeding.
2. prolonged bleeding after dental extractions.
3. petechae on oral mucosa.
Laboratory findings:
1. reduced platelet count
2. prolonged bleeding time.
THROMBOCYTOPENIA:

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1.
2.

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Purpura:
A purplish discolouration of skin and mucous membrane due to the spontaneous extravassation
of blood.
It is a symptom or sign rather than a disease
.
• As blood platelets play an important role in clotting, purpura occurs when platelets are defective
or deficient.
• Purpura also occurs when there is an increased fragility of the capillary walls.

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• Thrombocytopenic purpura due to decrease in number of platelets.
• Non-thrombocytopenic purpura where the number of platelets is normal,but the walls of the
capillaries are fragile, leading to extravasations of blood into the tissues
Types of purpura

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• Primary or essential: unknown etiology
• Secondary or symptomatic: known predisposing factor
Thrombocytopenic purpura

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• Maybe an autoimmune disease in which antibodies are produced against one’s own platelets.
• An acute form of the disease may occur in children after viral infections.
• Chronic type may occur in adults.
Secondary thrombocytopenic purpura
• Bone marrow depression.
• Leukemic infilteration of bone marrow.
• Infections like dengue,chicken pox , mumps, influenza, TB.
• Drug reactions to sedatives, antipyretics, anti histaminics
• Sepsis like DIC.
• Auto immune disease like SLE.
Primary thrombocytopenic purpura

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• Spontaneous appearance of purpuric hemorrhagic lesions of skin.
• Lesions vary from tiny red pinpoint petichiae to large purplish echymoses and
hematomas.
• Epistaxis, hematuria, hematemesis and malena.
• Possiblity of intracranial hemorrhage.
Clinical features

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Increase in number of circulating blood platelets.
Primary thrombocythaemia:1. myeloproliferative condition of unknown etiology.
2. sustained elevated platelet count.
>1million/mm3 because of clonal abnormality of multipotent
stem cell.
3. acquired somatic mutation of Janus kinase 2 gene.
4. increased risk of clot formation, increased risk of bleeding.
Secondary thrombocythaemia: 1. 450,000-1,000,000
2. secondary to some disease (iron deficiency anemia,
splenectomy, IBD, infections, tumors, drugs)
3. remains asymptomatic because of functional platelets.
THROMBOCYTHAEMIA/ THROMBOCYTOSIS

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Clinical features:
1. rare, 24/100,000
2. bimodal peak
3. female predilection.
4. clot development in brain, hands and feet.
5. increased risk of bleeding.
Oral manifestations:
1. spontaneous and profuse gingival bleeding.
2. prolonged bleeding after dental extractions.
3. petechae on oral mucosa
THROMBOCYTHAEMIA/ THROMBOCYTOSIS

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Laboratory findings:
1. counts: >450,000 cells/mm3
2. diagnosis of primary and secondary thrombocytosis.
Treatment:
1. secondary- treat underlying cause.
2. primary- daily dose of aspirin.
3. older people (>60 yrs) – increased risk of cardiovascular disease.
- lifelong administration of platelet lowering drugs
(hydroxyurea)
THROMBOCYTHAEMIA/ THROMBOCYTOSIS

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• Is the term used to describe a variety of diseases characterized by a qualitative defect in blood
platelets.
• The number of platelets is normal, but they show defective function.
Thrombasthaenia / Thrombocytopathy / Thrombocytasthenia

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