CASE REPORT

Disappearing
breast cysts

I Movson
MBChB, DMRD(UK)

PCorr
MBChB, FFRad(D)SA

Deparlment of Radi%gy, Addington
Hospital, University of Nata/, Durban,

South Africa

Abstract
The natural history
of simple breast
cysts is illustrated
by our patient with
multiple palpable
cysts which
disappeared
completely over a
six month period.
Interval
mammography is
all that is required
in these patients.

Case report
A 52 year-old woman was referred

for a mammogram because of a palpa-
ble mass in the outer quadrant of the
right breast. Mammography (Figure 1)
demonstrated multiple, well defined
masses bilaterally. There was no
microcalcification or spicultation. Ul-
trasound confirmed that these were
simple cysts. Cyst puncture was not

Figure 1,' Initial crania caudal mammogram
demonstrates bilateral breast cysts.

performed. A repeat mammogram was
advised after six months. This demon-
strated that the previous cysts had re-
solved completely (Figure 2).

Figure 2: Follow-up mammogram after a six month
interval confirms disappearance of the cysts.

20 SA JOURNAL OF RADIOLOGY. May 1998

Discussion
Breast cysts are common, occurring

in 30-50% of women at autopsy. I The
peak incidence is between 40-49 years
of age. The reason why cysts disappear
is unknown but is probably due to
changing oestrogen levels as they fre-
quently regress after menopause. Our
patient is unusual as the cysts disap-
peared so rapidly.

Screening programmes have dem-
onstrated that more than 50% of inter-
val cysts resolve within one year and
by two years, two-thirds had disap-
peared. At five years less than 12% of
cysts were unchanged.2

The cause of simple breast cysts is
unclear. They originate from the termi-
nal ductule lobular unit. They are
thought to result from coalescence of
lobular acini during ductule involution
or from ductule obstruction. The cyst
wall is composed of cuboidal to colum-
nar epithelium which is often multilay-
ered but can be atrophic.' Occasionally
cysts develop following duct ectasia, fat
necrosis, or oestrogen administration.'

Patients are often asymptomatic al-
though pain and tenderness may occur
from fluid tension in the cysts.The cysts
vary in size with the menstrual cycle."

On mammography, breast cysts are
indistinguishable from other benign
masses especially fibroadenomas - how-
ever ultrasound confirmation of a sim-
ple cyst establishes the diagnosis.

Interval annual mammography is all
that is required in these patients to con-
firm cyst regression.

References
1. Kopans D. Breast Imaging. Philadelphia: Lipincott. 1989;

266-267.

2. Brenner Rl, Bein ME, Sarti DA, Vinstein AL.
Spontaneous regression of interval benign cysts of the
breast. Radiology, 1994; 193: 365-368.

3. Haagensen CD. Disease of the breast. WB Saunders,
Philadelphia 1986.

4. Tucker AK. Textbook of mammography. Churchill
Livingstone, Edinburgh, 1993; 120-167.