Very important were the observations of Goldberger that in his six experimental cases the eruption first showed itself as a symmetrical involvement of the sides of the scrotum.
On the feet the dorsal eruption does not usually go above the malleoli and rarely involves the dorsal surfaces of the external toes although rather commonly affecting the great toe. In the U. S. the eruption may extend up the front and back of the leg (boot). The soles of the feet and palms of the hands are not infrequently involved in American cases as is also true of the tip of the elbow.
The eruption on the elbows rarely occurs until the patient takes to his bed and is probably incident to irritation over olecranon. Sandwith states that the skin lesions in Egypt are more widespread than those seen in Italy.
These skin eruptions show striking symmetry, marked delimitation from unaffected skin, with often more intense pigmentation at the border line, and they burn rather than itch.
Fig. 86.—“Butterfly” eruption on face of child two years old. (Deaderick and Thompson.)
In 1679 cases of pellagra Merk found 77% with eruption solely on backs of hands, 13% on backs of hands and neck, 8% on neck alone. The eruptions on dorsal surfaces of feet and calves of legs are chiefly seen in barefooted children. In the pellagra cases among Turkish prisoners Bigland noted an eruption on the hands in all but one of 232 cases. Rashes on the feet were noted in 111 cases and rashes on the face with bilateral symmetry were observed in 47 cases. One case showed a scrotal eruption.
The more advanced skin lesions are those of a dermatitis rather than an erythema. The affected skin is at first of a dull red color like a sunburn and later becomes reddish-brown or livid or chocolate-colored. Fox has likened the eruption to that of a carbolic acid burn.
The normal elasticity is lost and the area appears as a dry, scaly, atrophic patch—it is the skin of a very old man. The moist oedematous skin lesions are far more common in the U. S. than elsewhere and may show bullae and even gangrene. Such cases may show the gauntlet desquamation.