Indusium: the case made by an insect larva: a membranous layer of the embryo of Locustidae below the serosa. Explanation of Terms Used in Entomology John. B. Smith. serosa: the outer membrane that envelops the forming embryo, the amnion and the remainder of the egg. Explanation of Terms Used in Entomology John.
In essence, your body forms an allergic reaction to stress. Unfortunately, stress can not be eliminated with histamine, so instead, the histamine just causes hives to appear on your face, neck, chest and other parts of your body.
Praise to a reader, Shelley, who left a comment that her uncontrollable itching was diagnosed as Brachioradial pruritus. In short, Brachioradial pruritus is an itching sensation on the forearms. While there is not a definitive cause, speculation centers on sun exposure or nerve problems emanating from the neck.