• Platelet disorders (quantitative): Bleeding, bruising, petechia, or purpura Consider idiopathic thrombocytopenic purpura, thrombotic thrombocytopenic purpura, malignancy, viral disease
• Platelet disorders (functional): Consider in a patient with a lifelong history of bleeding despite negative laboratory work-up. Consider glycoprotein disorders (Bernard-Soulier syndrome, Glanzmann thrombasthenia), storage pool disease, von Willebrand's disease If platelets are abnormally shaped, consider May-Hegglin anomaly, Wiskott-Aldrich syndrome
• Haemophilia type A or B (factor VIII or IX deficiency) or other factor deficiencies: Classically presents with joint or soft-tissue bleeding; family history of bleeding in men (skipped generations)
• Factor inhibitors: Presentation similar to haemophilia, but onset is typically sudden with no patient or family history of bleeding
• Hereditary haemorrhagic telangiectasia: Telangiectasias over lips, tongue, nasal cavity, and skin; epistaxis
• Vasculitis or cryoglobulinemia: Neuropathy; pulmonary-renal involvement; purpura
• Leukemia: Abnormal complete blood count or peripheral blood smear
• Disseminated intravascular coagulation(DIC): Bleeding from multiple sites; prolonged prothrombin time and partial thromboplastin time
• Vitamin K deficiency: More common causes include malabsorption (bacterial overgrowth, celiac disease, chronic pancreatitis, inflammatory bowel disease, short-gut syndrome), poor diet (alcoholism, total parenteral nutrition) or drugs that bind vitamin K (cholestyramine [Questran]).

palpable purura if vasculitis or emboli

all purpura are non blanchable

petechia causes