Page 347 - Essential Haematology

Chapter 25 Bleeding disorders / 333

Figure 25.2 Henoch – Sch ö nlein
purpura: (a) unusually severe
purpura on legs with bullous
formation in a 6 - year - old child;
and (b) early urticarial lesions. (a) (b)

Figure 25.3 (a) Typical purpura;

and (b) massive subcutaneous
haemorrhage in a patient with
drug - induced thrombocytopenia. (a) (b)

Thrombocytopenia Failure of p latelet p roduction

Abnormal bleeding associated with thrombocytope- This is the most common cause of thrombocytope-
nia or abnormal platelet function is characterized nia and is usually part of a generalized bone marrow
by spontaneous skin purpura (Fig. 25.3 ) and failure (Table 25.2 ). Selective megakaryocyte
mucosal haemorrhage and prolonged bleeding after depression may result from drug toxicity or viral
trauma (Table 25.1 ). The main causes of thrombo- infection. Rarely, it is congenital as a result of muta-

cytopenia are listed in Tables 25.2 and 25.3 . tion of the c - MPL thrombopoietin receptor, in