Skin diseases and allergic reactions 

It is a highly infectious disease caused by Varicella zoster virus (VZV)

Pemphigus vegetans is a rare variant of pemphigus vulgaris, characterized by vegetating (wart-like), hypertrophic plaques that develop after fragile blisters rupture. It is a chronic autoimmune blistering disease in which autoantibodies attack proteins responsible for adhesion between epidermal cells, resulting in blister formation followed by excessive tissue overgrowth during healing.

Bullous pemphigoid is a chronic autoimmune blistering disease that primarily affects older adults. It is characterized by the development of tense, fluid-filled blisters (bullae) on normal or erythematous skin due to autoantibodies directed against proteins of the basement membrane zone that anchor the epidermis to the dermis.

Is a disease caused by deficiency of a variety of specific factors, nicotinic acid being the most important. Cardinal signs: diarrhea, dermatitis (sites exposed to sun and pressure) and dementia.

Is a delayed hypersensitivity reaction following skin coming into contact with a particular chemical. This may be a dye, perfume, rubber, nickel, drugs, skin preparations containing lanolin, iodine, antihistamines, neomycin etc