A 36-year-old woman presents to her general practitioner (GP) complaining of spontaneous bruising mainly on her legs. The bruising has been noticeable over the last 4–6 weeks. She cannot remember any episodes of trauma. In addition her last two menstrual periods have been abnormally heavy, and she has suffered a major nosebleed. She otherwise feels well, and is working full time as a secretary. There is no significant past medical history. She is married with one daughter aged 11 years. There is no family history of a bleeding disorder. She is a non-smoker and drinks a small amount of alcohol socially.
Examination On examination there are multiple areas of purpura on her legs and to a lesser extent on her abdomen and arms. The purpuric lesions vary in colour from black–purple to yellow. There are no signs of anaemia, but there are two bullae in the mouth and there is spontaneous bleeding from the gums. There are no retinal haemorrhages on funduscopy. Blood pressure is 118/72mmHg. Examination of the cardiovascular, respiratory and abdominal systems is unremarkable.
Normal Haemoglobin 10.9g/dL 11.7–15.7g/dL Mean corpuscular volume (MCV) 83fL 80–99fL White cell count 4.3 109/L 3.5–11.0 109/L Platelets 4 109/L 150–440 109/L Sodium 139mmol/L 135–145mmol/L Potassium 4.3mmol/L 3.5–5.0mmol/L Urea 5.4mmol/L 2.5–6.7mmol/L Creatinine 76amol/L 70–120amol/L Glucose 4.3mmol/L 4.0–6.0mmol/L
Clotting screen: normal Blood film: decreased platelets
INVESTIGATIONS
Questions • What is the likely diagnosis? • How would you further investigate and manage this patient?
ANSWER
This woman has spontaneous bruising due to idiopathic thrombocytopenic purpura (ITP). She has profound thrombocytopenia with a platelet count of 4 109/L. An increased tendency to bleed or bruise can be due either to platelet, coagulation or blood vessel abnormalities. Platelet/vessel wall defects cause spontaneous purpura in the skin and mucous membranes or immediately after trauma. Coagulation defects cause haematomas and haemarthroses usually with a time delay after trauma. A positive family history or early onset of bleeding suggests haemophilia. The distribution of bruising may suggest the diagnosis. Thrombocytopenic purpura is most evident over the ankles and pressure areas. Retinal haemorrhages tend to occur if there is a combination of severe thrombocytopenia and anaemia. Senile purpura and steroid-induced bruising occur mainly on the forearms and backs of the hands. Henoch–Schönlein purpura typically occurs over the extensor aspects of the limbs and buttocks. Scurvy causes bleeding from the gums and around the hair follicles. Non-accidental injury in children can present with bruising. ITP usually occurs in young and middle-aged women. In addition to the purpuric lesions in the skin there may be menorrhagia, epistaxes or occult or overt gastrointestinal haemorrhage. In this woman’s case there is a mild normochromic normocytic anaemia due to recent blood loss. Splenomegaly is usually absent. The causes of thrombocytopenia can be divided into disorders of reduced production of platelets or decreased survival of platelets. Decreased production of platelets can be due to marrow infiltration, for example by leukaemia or malignancy, or as a result of toxins, for example alcohol, drugs (e.g. chemotherapy), radiation or viruses (e.g. cytomegalovirus [CMV]). Platelet survival is reduced in ITP due to antibodies directed against the platelets. Secondary causes of ITP include systemic lupus erythematosus (SLE), lymphoma, drugs such as quinine, heparin and alpha-methyldopa and hypersplenism. Platelet consumption is increased in disseminated intravascular coagulation and thrombotic thrombocytopenic purpura (TTP). The patient should be immediately referred to a haematology unit. Platelet transfusion is usually given if there is significant bleeding or the platelet count is less than 15 109/L to prevent a major spontaneous bleed. Investigations include assaying for platelet-associated immunoglobulin G (IgG), excluding other causes of thrombocytopenia such as SLE and performing a bone marrow aspirate. In this case it will show increased numbers of megakaryocytes consistent with increased platelet turnover. The platelet count in ITP normally will rise rapidly after commencement of either corticosteroids or intravenous immunoglobulin. The disease often runs a remitting and relapsing course. Splenectomy may be necessary.