Congenital
abnormalities of the spleen
Absence of the spleen is rare, and when it
occurs is often associated with congenital heart disease. Patients without a
spleen are occasionally subject to fatal infection.
Splenunculi
These are single or multiple accessory spleens
which are found near the hilum of the spleen in 50 per cent, related to the
splenic vessels and behind the tail of the pancreas in 30 per cent, or in the
splenic ligaments and mesocolon in the remainder. Up to 20 per cent of people
have such splenunculi and most are no larger than 2 cm in diameter. Their
importance lies in the fact that if not removed at the time of splenectomy they
will undergo hyperplasia and may well be the site of persistent disease.
Hamartoma
Rarely, these are found in the spleen, usually
being found incidentally at post-mortem examination. They vary in size from less
than 1 cm in diameter to masses large enough to produce abdominal swelling.
There are two varieties: one mainly lymphoid resembling the white pulp and the
other resembling the red pulp. They are occasionally seen incidentally on CT
scanning.
Splenic
cysts
Nonparasitic cysts of the spleen are rare. They
consist of true cysts formed from embryonal rests and include dermoids and
mesenchymal inclusion cysts, or false cysts resulting from trauma which contain
serous or haemorrhagic fluid. They can be clearly demarcated on scanning,
punctured, drained and sclerosed. Operative removal is rarely, if ever,
indicated.