Introduction:
Sickle cell disease (SCD) is a group of inherited diseases characterised
by the presence of haemoglobin S (Hb S), either by homozygosity for the
sickle mutation (Hb SS) or by mixed heterozygosity with another
beta-globin variant (e.g. sickle beta thalassaemia, Hb SC disease). It
is one of the most common haemoglobinopathies, especially in Middle
Eastern countries. The hallmarks of SCD are recurrent vaso-occlusive
crises and haemolytic anaemia. Vaso-occlusive crises manifest as acute
pain crises, acute chest syndrome and priapism - they are mainly caused
by obstructions of the microcirculation and lead to tissue hypoxia and
severe pain.[1][2][3]
Priapism is defined as a persistent erection of the penis that is not
associated with sexual interest or desire. It can occur with low flow
(ischaemic, vaso-occlusive) or high flow (non-ischaemic). In some
series, it is estimated that 35 to 45 per cent of men with sickle cell
disease (SCD) are affected by priapism. Ischaemic episodes lasting ≥4
hours (severe episodes) are of particular concern as they carry a high
risk of permanent tissue damage from penile compartment syndrome. There
is another vriant of ischaemic priapism, known as stuttering priapism,
which is characterised by brief, recurrent episodes of transient,
self-limited priapism.[4][5]
Recent therapeutic advances have seen the approval of crizanlizumab, a
monoclonal antibody targeting P-selectin, by the FDA in 2019 for
reducing the frequency of SCD-related vaso-occlusive crises.
Nonetheless, the efficacy of crizanlizumab in managing SCD-associated
priapism has yet to be thoroughly investigated, underscoring a vital
area for further clinical exploration [6].