CLINICAL IMAGES

Computed
tomography

•appearances In
paediatric tuberous

sclerosis
S Andronikou

MB ChB, FCRad(D), FRCR (Lond)

C Weiman
MBChB

E Kader
MBChB

R Joubert
MBChB

Department of Paediatric Radiology
University of Cape Town and Institute of Child
Health, Red Cross War Memorial Children's

Hospital, Cape Town

Identification of one or more of
three characteristic imaging findings
may make the radiological diagnosis
of tuberous sclerosis in childhood.
The computed tomography (CT)
scan appearances vary according to
age and it is important that the radiol-
ogist be aware of this, so as to make
the correct diagnosis.

Subependymal
hamartomas

These are noted on the ventricular
surface of the caudate nucleus. Less
common sites include the frontal and
temporal portions of the lateral ven-
tricles as well as around the 3rd and
4th ventricles. These lesions change
with patient age - in the first year of

life they are rarely calcified, but after
1 year of age they calcify commonly.
Variable contrast enhancement is
noted, ranging from not at all to
marked enhancement. Giant cell
tumour is an enlarging subependymal
nodule at the foramen of Monro and
is recognised by its location and evi-
dence of growth on serial studies.
These only rarely degenerate into
high-grade infiltrating lesions, when
they are seen to invade parenchyma or
show rapid enlargement.

Fig. 1. Bilateral calcified subependymal hamar-
tomas at the foraminae of Monro (arrows) in an
older child. These lesions may also occlude the
foraminae resulting in hydrocephalus.

Cortical hamar-
tomas/tubers

Calcification of these lesions
increases with increasing age. They
may be gyriform simulating Sturge-

Figs 2a and 2b. Pre and post-contrast CT scans show a left-sided, partially calcified subependymal nodule at
the foramen of Monro, which shows marked contrast enhancement (closed arrows). The open arrows indicate
white matter lesions of low density with partial calcification (high-density focus). These do not enhance with con-
trast.

46 SA JOURNAL OF RADIOLOGY. March 2002



CLINICAL IMAGES

Fig. 3. Subependymal calcified hamatomas
(arrows) are seen along the sutiece of the bodies of
the lateral ventricles. A cortical tuber, which is par-
tially calcified, is also present (open arrow).

Weber syndrome. These do not usual-
ly enhance (unlike subependymal
nodules) unless they are degenerating.
They also vary in appearance with age

Fig. 4. A large enhancing midline mass at the fora-
men of Monro developed at the site of previously
identified harmatomas. This is now termed a giant
cell astrocytoma.

- below 1 year of age they are oflow
density and are associated with broad
gyri. With increasing age the density
increases, until adulthood where dif-

ferentiation from normal cortex can
be difficult unless they are calcified.

White matter
lesions

These are low-density well-defined
areas in the cerebral white matter
which do not enhance but can calcify,'

MRI is more sensitrve in
identifying all the above lesions.
Varying signal intensities on Tl, T2
and gadolinium-enhanced stuclies are
noted according to the patient's age.
MRI also shows characteristic curvi-
linear high T2 signal intensity exten-
sions from subependymal hamar-
tomas to cortical tumours which rep-
resent unmyelinated, disordered cells
along the path of the glial-neuronal
units (Figs 2-4).

Reference
I. Barkovich A]. Paediatric Neuroimaging. 2nd ed.

Philadelphia: Lippincott-Raven, 1996: 296-304.

47 SA JOURNAL OF RADIOLOGY • March 2002