812 
DISEASES OF THE FOOT. 
pedis, which show a depression at the affected spot, corresponding in 
form to the keratoma. 
Keratomata therefore result from chronic, productive inflammation. 
Sometimes the condition is accompanied by superficial suppuration. On 
the other hand, infectious inflammation of the podophyllous membrane 
may constitute the first phase and be succeeded by a chronic productive 
process. For this reason the symptoms vary. 
The diagnosis of keratoma during life can only he assured when the 
growth appears on the plantar surface. The white line then seems to 
be thrust towards the centre of the sole at the point affected, the inner 
border of the keratoma itself forming, in fact, the white line. Where the 
growth is due to a split in the horn, the wall is divided from the new 
growth by a space. 
Keratomata, derived from the sensitive laminae, frequently produce 
chronic inflammation of the latter. In such cases a secretion, which is 
Fig. 311. —Portion of the inner surface of 
the wall showing changes after old- 
standing corn, a , Horn tumour. 
sometimes watery, sometimes puru¬ 
lent, discharges from the space 
between the horny and sensitive 
laminae. A probe may often be 
passed to the upper margin of the 
split, i.e., as far as the upper end 
of the keratoma. 
Occasionally that portion of the 
external wall of the hoof correspond¬ 
ing to the keratoma is bulged out¬ 
wards, forming a projection extend- 
This condition is commonest 
ing from the coronet to the bearing surface. 
when the keratoma grows from the coronet; the surface of this protruding 
part is sometimes rough and inclined to split. 
Keratomata usually, but not always, produce lameness, which exhibits 
all the symptoms of foot lameness, except acute inflammation. In excep¬ 
tional cases, even these (increased warmth and pulsation) may be detected. 
When infectious processes are absent and the keratoma is of small size 
there may be no lameness, which is usually due either to pressure of the 
new growth on the pedal bone or to inflammation. 
The prognosis depends principally on the presence or absence of 
lameness, and on the possibility of removing the diseased growth. It is, 
therefore, important to know whether the keratoma has (1) originated in 
the coronary region, or (2) from the lower sections of the sensitive lamina}. 
In the first case, its removal not only offers great difficulty, but enforces 
a long rest, as the hoof is divided to a considerable extent and a large 
amount of horn removed. In the second case, the time required for 
recovery is in proportion to the distance the diseased growth extends 
