A precise picture of the condition is difficult to draw, for clinical generalisations do not necessarily apply to the individual case and the
condition itself is extremely variable and unpredictable. In the description which follows, the term keloid will be used to cover both conditions.
The tendency to develop keloids appears to diminish with age, but it is not possible in practice to forecast whether any particular patient will develop one.
Nevertheless, any incision in a known ‘keloid former’ is more likely to develop into a keloid than a similar incision in a random patient, and recurrence following simple excision of a keloid is highly probable. Keloids are much more common in the black than in the Asian patient, and more common in the Asian than in the white. The black patient also exhibits the condition in its most active form and the ‘tumours’ can on occasion reach quite grotesque proportions.
In the white patient, on the other hand, even the frank keloid does eventually become less active, and takes on the characteristics and activity rather of a hypertrophic scar.
Certain areas of the body have a particular
tendency to produce keloids ; the presternal area is probably the most prone of all and here oddly enough the shape of the keloid often shows a sex difference -in the male it tends to be irregular in outline, in the female the pull of the breasts commonly gives it a butterfly outline. The deltoid area is another notorious site, most often following BCG innoculation. The earlobe is the third common site, usually after ear piercing.
A scar may become keloid in only part of its length, a feature which shows particularly in the neck where the vertical scar is prone to keloid change while the horizontal scar is rarely affected. If a scar of the neck is excised incorporating Z-plasties it is not uncommon for the horizontal scars to be completely flat and soft, while the vertical limbs of the Zs show keloid or at very least hypertrophic change. In general, scars in lines of election show less tendency to keloid than those which cross them.