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Purpura

Specialties > Haematology

Differential Diagnosis Schema 🧠

Non-Thrombocytopenic Purpura

  • Vasculitis: Inflammation of blood vessels, e.g., Henoch-Schönlein purpura (HSP), typically presents with palpable purpura and systemic symptoms.
  • Senile purpura: Occurs in elderly patients due to fragile blood vessels, typically on the forearms and hands.
  • Steroid-induced purpura: Long-term corticosteroid use can cause skin thinning and purpura.
  • Infectious causes: Meningococcemia, infective endocarditis, and other severe infections can cause purpura due to disseminated intravascular coagulation (DIC).
  • Amyloidosis: Deposits of amyloid in the vessel walls can lead to purpura.
  • Scurvy (Vitamin C deficiency): Causes defective collagen synthesis, leading to fragile blood vessels and purpura.
  • Waldenström’s macroglobulinemia: A lymphoplasmacytic lymphoma that can cause hyperviscosity syndrome and purpura.
  • Cryoglobulinemia: Immune complex deposition that can lead to vasculitis and purpura, often associated with hepatitis C.
  • Connective tissue disorders: Such as systemic lupus erythematosus (SLE), which can cause vasculitis and purpura.
  • Chronic liver disease: Associated with coagulopathy and vascular fragility leading to purpura.
  • Ehlers-Danlos syndrome: A connective tissue disorder that can cause fragile blood vessels and purpura.

Thrombocytopenic Purpura

  • Immune thrombocytopenic purpura (ITP): Autoimmune condition leading to isolated thrombocytopenia and purpura, often without systemic symptoms.
  • Thrombotic thrombocytopenic purpura (TTP): Characterized by thrombocytopenia, microangiopathic hemolytic anemia, neurological symptoms, renal impairment, and fever.
  • Disseminated intravascular coagulation (DIC): Caused by widespread activation of the coagulation cascade, leading to thrombocytopenia and purpura, often in the context of severe infection or malignancy.
  • Heparin-induced thrombocytopenia (HIT): An immune-mediated adverse effect of heparin leading to thrombocytopenia and thrombosis.
  • Leukemia: Hematologic malignancies can lead to bone marrow failure and thrombocytopenia, presenting with purpura.
  • Aplastic anemia: Bone marrow failure leading to pancytopenia, including thrombocytopenia and purpura.
  • Viral infections: Viral infections such as HIV, Epstein-Barr virus (EBV), and cytomegalovirus (CMV) can cause thrombocytopenia and purpura.
  • Hemolytic uremic syndrome (HUS): Similar to TTP, associated with renal failure, often following a diarrheal illness in children.
  • Myelodysplastic syndromes: Clonal hematopoietic disorders that can lead to thrombocytopenia and purpura.
  • Chemotherapy-induced thrombocytopenia: Bone marrow suppression following chemotherapy leading to thrombocytopenia and purpura.
  • Drug-induced thrombocytopenia: Various drugs, including antibiotics, anticonvulsants, and others, can cause immune-mediated thrombocytopenia.

Key Points in History 🥼

History of Presenting Complaint

  • Onset: Sudden onset suggests an acute cause like infection, drug reaction, or DIC; chronic onset suggests a more insidious condition like leukemia or connective tissue disease.
  • Location: Widespread purpura may indicate a systemic cause; localized purpura may suggest trauma or a localized infection.
  • Associated symptoms: Fever, weight loss, night sweats may suggest malignancy or infection; arthralgia and myalgia may indicate vasculitis or connective tissue disease.
  • Medication history: Important to identify potential drug-induced thrombocytopenia or drug reactions.
  • Bleeding tendency: Epistaxis, gum bleeding, or menorrhagia suggests a platelet or coagulation disorder.
  • Recent infections: Viral infections can precipitate conditions like ITP or HUS.
  • Recent vaccinations: Consider ITP following vaccination, particularly in children.
  • Trauma history: Consider traumatic causes of purpura, particularly in localized cases.
  • Occupational and environmental exposures: Consider chemical or toxin exposure, particularly in occupational settings.
  • Family history: Assess for inherited conditions such as hemophilia or von Willebrand disease.
  • Dietary history: Consider vitamin deficiencies, particularly vitamin C deficiency (scurvy).
  • Recent travel: Consider travel-associated infections or exposure to pathogens associated with purpura.
  • Vaccination history: Particularly relevant in children or those with immune-mediated thrombocytopenia.
  • Alcohol consumption: Chronic alcohol use may contribute to liver disease and coagulopathy.
  • Stress or recent surgery: Consider stress-related triggers for conditions like TTP.
  • Social history: Occupational or recreational exposures that may increase risk.
  • Pregnancy: Consider gestational thrombocytopenia, HELLP syndrome, or other pregnancy-related causes of purpura.

Background

  • Medical history: Chronic diseases such as liver disease, kidney disease, or autoimmune conditions may predispose to purpura.
  • Surgical history: Recent surgeries may increase the risk of DIC or HIT.
  • Family history: Consider genetic conditions like von Willebrand disease, hemophilia, or inherited platelet disorders.
  • Medication history: Review for drugs that can cause thrombocytopenia or affect coagulation.
  • Social history: Occupational and lifestyle factors that may contribute to risk, such as alcohol use or exposure to toxins.
  • Psychosocial factors: Consider stress, recent life events, or other psychosocial factors that may contribute to immune-mediated conditions.
  • Environmental exposures: Consider recent exposure to infectious agents, particularly in travel history.
  • Nutritional status: Poor nutrition, particularly in elderly or malnourished patients, may predispose to purpura.
  • Immunization status: Relevant in patients with a history of ITP or other immune-mediated conditions.
  • Substance use: Including illicit drugs that may contribute to thrombocytopenia or vasculitis.
  • Recent blood transfusions: Consider alloimmunization or transfusion reactions as potential causes.
  • Endocrine disorders: Conditions like diabetes may increase the risk of vascular fragility.
  • Previous hematological investigations: Review previous blood counts or coagulation studies for trends.
  • Systemic symptoms: Consider weight loss, fever, or night sweats as red flags for underlying malignancy or systemic disease.

Possible Investigations 🌡️

Laboratory Tests

  • Full blood count (FBC): To assess platelet count, white cell count, and hemoglobin level, which can help differentiate between different causes of purpura.
  • Coagulation profile (PT, APTT, INR): To evaluate for coagulopathy, as seen in DIC, liver disease, or anticoagulant use.
  • Blood film: To assess for platelet morphology, presence of schistocytes in TTP or DIC, or abnormal cells in leukemia.
  • Renal function tests: To assess for renal impairment, particularly in HUS or TTP.
  • Liver function tests (LFTs): To assess for liver disease, which may cause coagulopathy and purpura.
  • Bone marrow biopsy: Indicated if leukemia, aplastic anemia, or myelodysplastic syndrome is suspected.
  • Viral serology: To test for HIV, hepatitis C, EBV, or CMV in cases of suspected viral-induced thrombocytopenia.
  • Antinuclear antibody (ANA) and other autoimmune screens: To assess for autoimmune conditions such as SLE.
  • D-dimer: Elevated in DIC, thromboembolism, or severe infection.
  • ADAMTS13 activity: To assess for TTP, which is characterized by severe deficiency of this enzyme.
  • Haptoglobin and lactate dehydrogenase (LDH): Elevated LDH and low haptoglobin suggest hemolysis, as seen in TTP or HUS.
  • Urinalysis: To check for hematuria or proteinuria, which may indicate renal involvement as in HUS or vasculitis.
  • Immunoglobulin levels: To assess for conditions such as multiple myeloma or Waldenström’s macroglobulinemia.
  • Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP): Elevated in vasculitis, infection, or malignancy.
  • Anti-platelet antibody tests: To assess for immune-mediated thrombocytopenia, such as ITP.
  • Genetic testing: May be indicated in hereditary thrombocytopenic conditions or connective tissue disorders.
  • Thrombin time (TT) and fibrinogen levels: Useful in assessing coagulation status, particularly in DIC.
  • Serum protein electrophoresis: To assess for paraproteins in conditions like multiple myeloma.
  • Vitamin C levels: To check for deficiency in suspected cases of scurvy.
  • Blood cultures: If sepsis or infective endocarditis is suspected.
  • Flow cytometry: May be used in the assessment of hematologic malignancies.
  • Tryptase levels: Elevated in anaphylaxis or mast cell disorders, which may cause purpura.
  • Anti-glomerular basement membrane (anti-GBM) antibodies: If Goodpasture’s syndrome is suspected.
  • Cerebrospinal fluid (CSF) analysis: If meningococcemia or CNS vasculitis is suspected.
  • Bilirubin levels: To assess for hemolysis in conditions like TTP.

Imaging and Other Tests

  • Chest X-ray: To assess for signs of infection, malignancy, or other underlying conditions.
  • Abdominal ultrasound: To assess for splenomegaly or other abdominal pathologies that may contribute to purpura.
  • CT scan: Useful in assessing for underlying malignancies, particularly in the chest, abdomen, or pelvis.
  • Echocardiogram: To assess for infective endocarditis if cardiac involvement is suspected.
  • MRI brain: Indicated if CNS involvement is suspected, particularly in cases of TTP or vasculitis.
  • Duplex ultrasound: To assess for deep vein thrombosis if there is suspicion of thrombotic events in TTP.
  • Endoscopy: May be indicated if gastrointestinal bleeding is suspected in the context of thrombocytopenia or coagulopathy.
  • Bone density scan (DEXA): To assess bone health in patients with long-term steroid use or chronic illness.
  • PET scan: Useful in the staging of lymphomas or other malignancies associated with purpura.
  • Venography: To assess for venous thrombosis in cases of suspected thrombotic complications.
  • Capsule endoscopy: To evaluate for small bowel bleeding in cases of unexplained anemia or GI bleeding associated with purpura.
  • Dermatological consultation: To assess skin biopsy if vasculitis or other dermatologic causes of purpura are suspected.
  • Electrocardiogram (ECG): To assess for arrhythmias or other cardiac involvement, particularly in systemic diseases like SLE.
  • Holter monitoring: If there are transient arrhythmias suspected in systemic diseases presenting with purpura.
  • Electromyography (EMG): To assess for neuromuscular involvement in systemic vasculitis or other conditions.
  • Colonoscopy: To assess for colonic involvement in conditions like HUS or vasculitis-associated gastrointestinal disease.

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Haematology