Thrombocytopenia and immune thrombocytopenia: Case

This girl has the classic presentation of newly diagnosed immune thrombocytopenia, ITP. She is a well preschool child, two weeks after a viral illness, with the sudden bruising and the petechiae, the isolated thrombocytopenia at 8 times ten to the nine per litre, the normal haemoglobin and white cell count, the large platelets and the absence of blasts on the film, and the absence of the organomegaly. The small nosebleed that stopped with pressure is the mild mucosal bleeding, and it places her at the boundary of the mild and the moderate bleeding grade. [1][4]

Interpretation of the findings

The key findings are the isolated thrombocytopenia, the normal blood film, and the well child. The platelet count of 8 times ten to the nine per litre is well under the threshold of 100 times ten to the nine per litre, and it is the only abnormality on the full blood count. The blood film shows the large platelets, which is the expected finding in ITP because the young platelets are larger, and the absence of the blast cells, the schistocytes, and the other abnormalities that would point to the acute leukaemia, the haemolytic uraemic syndrome, or another alternative diagnosis. The normal haemoglobin and white cell count exclude the marrow infiltration, and the absence of the hepatosplenomegaly and the lymphadenopathy exclude the leukaemia and the infiltrative disorders at the bedside. [4]

The diagnosis of ITP is therefore made on the combination of the isolated thrombocytopenia, the normal film, the well child, and the absence of the organomegaly, and it is a clinical diagnosis made by exclusion. A bone marrow aspirate is not indicated, because the ASH 2019 guideline recommends against the routine marrow aspirate in the child with the typical presentation. The marrow is reserved for the atypical case, the case with the other cytopenias, the blasts, or the organomegaly. [1]

Management: observation

The ASH 2019 guideline recommends, as a strong recommendation based on moderate-quality evidence, observation over treatment for the child with newly diagnosed ITP and no bleeding or only mild skin bleeding, regardless of the platelet count. This girl has the mild bleeding, the bruising, the petechiae, and the small nosebleed that stopped with pressure, and the decision rests on whether the nosebleed tips her into the moderate bleeding grade. The bleeding grade is the clinical judgement, and the fellow who grades the nosebleed that stopped easily as mild will observe, while the fellow who grades it as moderate will treat. [1]

For this girl, the nosebleed that stopped with pressure and the otherwise well child place her at the mild end, and the decision is observation with the close monitoring. The rationale is threefold. The bleeding risk in the child with the mild bleeding is low, the treatments carry their own harms such as the IVIG infusion reactions and the corticosteroid side effects, and about 70 to 80 percent of children remit within six months, per the ICIS twelve-month follow-up registry. The platelet count is monitored, but it is not the trigger for the treatment, because the bleeding severity drives the decision. [1][6]

Counselling the family

The counselling addresses the diagnosis, the observation strategy, the safety-net, and the outlook, because the family is frightened by the alarming blood test and the bruising, and the reassurance is as important as the management. The family is told that the girl has the immune thrombocytopenia, that it is the commonest cause of the low platelets in a well child, that it often follows a viral illness, and that it usually resolves on its own within weeks to months. They are told that the observation strategy is safe and is the recommended approach, that the girl will avoid the contact sports and the platelet-interfering medications, and that the count will be monitored until it rises. [1]

The safety-net is given in writing, because the family that has the written plan is the family that acts on it. The family is taught to return immediately for the severe headache, the persistent bleeding, or the altered consciousness, because these may signal the intracranial haemorrhage. They are taught to avoid the non-steroidal anti-inflammatories, such as the ibuprofen, and the aspirin, because these interfere with the platelet function, and to use the paracetamol for the fever or the pain instead. They are taught to avoid the intramuscular injections and the contact sports, and to apply the firm pressure for any minor bleed. [1]

The follow-up and the safety-net

The girl is reviewed in the haematology clinic within a week to ten days, and the count is monitored. The expectation is the rise in the platelet count over the days to weeks, and the resolution of the bruising and the petechiae. If the count rises and the bleeding resolves, the observation continues, and the intervals between the reviews lengthen. If the bleeding worsens to the moderate or the severe grade, the girl moves to the first-line therapy, with the IVIG at 0.8 to 1 g per kg as a single dose, the short course of corticosteroids, or the anti-D at 50 to 75 micrograms per kg for the Rh-D positive child with the negative direct antiglobulin test and the intact spleen. [1]

If the thrombocytopenia persists beyond twelve months, the girl moves into the chronic phase, and about 20 to 25 percent of children reach this phase. The chronic phase is managed by the second-line therapy, led by the thrombopoietin-receptor agonists such as the eltrombopag, and supported by the multidisciplinary team. The long-term outlook is favourable, with the great majority remitting, and the intracranial haemorrhage, the feared complication, being rare, with an incidence estimated below one percent. The family is reassured that with the observation, the safety-net, and the first-line therapy if needed, the girl is expected to recover fully. [1][6]