A blood film was examined on an 8‐year‐old boy with thrombocytopenia. A diagnosis of immune thrombocytopenic purpura (“ITP”) had been made 7 years previously, and he had received treatment with high dose intravenous immunoglobulin (IVIG), corticosteroids, and blood and platelet transfusions for severe epistaxis. He had been noted to have” little response” to IVIG on at least one occasion. Treatment with eltrombopag commenced in 2017, and bleeding symptoms responded with fewer episodes of epistaxis, although any rise in the platelet count was not sustained. In 2019 this was changed to romiplostim due to persistent thrombocytopenia.

An automated platelet count was 32 × 10⁹/L but the instrument was unable to produce a mean platelet volume (MPV) estimation. His blood film showed normal red cell and leucocyte morphology (with no inclusions in neutrophils), but the platelets were unexpectedly large and sometimes formed loose aggregates (Images). Platelet granularity was normal. The macrothrombocytopenia suggested an inherited condition rather than immune thrombocytopenia and Next Generation Sequencing for a targeted panel of genes was therefore carried out. This identified a homozygous, likely pathogenic variant: GP1BB: c.47 T > C, p.(Leu16Pro). Follow‐up immunophenotyping showed absent expression of platelet glycoprotein Ib (CD42), confirming a diagnosis of Bernard‐Soulier Syndrome.

Immune thrombocytopenia, or more specifically autoimmune thrombocytopenia, is to some extent a diagnosis of exclusion since platelet autoantibodies are not always identifiable. Examination of the blood film is important in the recognition of inherited causes of thrombocytopenia and in avoiding inappropriate treatment. It is important to assess not only platelet size and granularity but also granulocytes for May‐Hegglin inclusions and erythrocytes for stomatocytosis (which may indicate phytosterolemia). The advent of targeted panels for the identification of relevant mutations has made diagnosis more straightforward.

检查了一个患有血小板减少症的8岁男孩的血膜。7年前已经诊断出免疫性血小板减少性紫癜（“ ITP”），他接受了大剂量静脉注射免疫球蛋白（IVIG），皮质类固醇以及血液和血小板输注的治疗，以防止严重的鼻st。人们注意到他至少有一次对IVIG“反应迟钝”。2017年开始使用Eltrombopag治疗，出血症状缓解了鼻st发作，尽管血小板计数没有任何持续增加。由于持续性血小板减少症，在2019年更改为romiplostim。

自动血小板计数为32×10 ⁹ / L，但该仪器无法产生平均血小板体积（MPV）估计值。他的血膜显示正常的红细胞和白细胞形态（中性粒细胞中没有夹杂物），但血小板出乎意料的大，有时形成疏松的聚集体（图片）。血小板粒度正常。大血小板减少症提示遗传性疾病而非免疫性血小板减少症，因此针对目标基因组进行了下一代测序。这确定了纯合的，可能是致病的变体：GP1BB：c.47 T> C，p。（Leu16Pro）。后续免疫表型分析显示血小板糖蛋白Ib（CD42）的表达缺失，从而证实了伯纳德-苏里耶综合症的诊断。

免疫性血小板减少症，或更具体地说是自身免疫性血小板减少症，在某种程度上是排除诊断，因为血小板自身抗体并不总是可识别的。血膜检查对识别血小板减少的遗传原因和避免不适当的治疗很重要。重要的是，不仅要评估血小板的大小和粒度，还应评估粒细胞的May-Hegglin夹杂物和红细胞的造血作用（这可能表示植物甾醇血症）。用于鉴定相关突变的靶向检测组的出现使诊断更加简单。