S.KEY584]	CLINICAL	93
The outstanding clinical stigmata of the disease are the colour of the Clinical
urine and the development of a skin eruption known as hydroa vaccini- P^ictuf'^e
forme. In many of the original cases the skin lesions were so disfiguring
that a diagnosis of congenital syphilis was made. The skin lesion occurs Skin lesions
on those portions of skin exposed to sunlight, namely, the face, neck,
and backs of the hands, and, in the young, the knees. Its earliest
manifestation is the appearance of bullae of various sizes containing
either colourless or blood-stained fluids. On healing these leave per-
manent scars, and if infection takes place very severe disfigurement may
result. In some cases amputation of the fingers has had to be performed.
Occasionally bullae may appear on the conjunctivae, and this event
is usually followed by the complete destruction of both eye-balls. The
skin shows deep brown pigmentation in cases of long standing. Not all
patients with haematoporphyria congenita are attacked by the skin
condition; it appears to be less intense in men than in women.
Another clinical manifestation is the deposit of deep brown pigment Pigmentation
in the bones. This renders the bones of the hand, for example, visible °^m ^and
on transillumination. This again is not found in every case. In some
cases pigmentation of the enamel of the milk-teeth appears. In one of
Garrod's cases the child cut a tooth at the age of nine months, and this
was definitely pink. At twenty-two months the child had twelve teeth,
all of which were of a pinkish- red colour indistinguishable from that of
the gurns.
Of other clinical manifestations the concomitant infection with tuber- Association
culosis appears to be important. The review of a large series of cases
convinced Garrod that patients with haematoporphyria congenita were
specially liable to this disease.
Apart from the above-mentioned conditions there appears to be little Enlargement
else which can be found in the clinical examination of such patients. °/_pl^ ^imd
In later life enlargement of the spleen appears to be common, and in
some cases enlargement of the liver has been described: this has led to
the belief that the cause of the disease lies in some faulty functioning of
this organ, and there also appears to be a certain amount of experi-
mental evidence to support this.
The cause of the skin lesion appears to be the sensitization of the Sensitivity
surface of the body to the action of ultra-violet rays, This thesis finds j^^M *°
considerable support in experimental work. It has been known for many
years that the presence of fluorescent pigments increases sensitivity to
light in lower organisms such as the paramecium. Hausmann showed
that the injection of haematoporphyrin into the higher animals had the
same effect. Thus the injection of 0-01 gram of haematoporphyrin into
a white mouse will not cause any change in the animal if it is kept
in the dark; exposure to bright light, however, will result in the death
of the animal in a few hours. Similar experiments were performed 011
the human subject by Meyer-Betz. This worker injected 0-2 gram of
haematoporphyrin intravenously into himself. Shortly after the injection
he irradiated the skin of his arm with ultra-violet rays for forty minutes.