Erythrasma is an extremely rare disease, due to the presence and growth in the epidermic structures of the vegetable parasite--the _microsporon minutissimum_. It is characterized by small and large, slightly furfuraceous, reddish-yellow or reddish-brown patches, occurring usually on warm and moist parts, such as the axillary, inguinal, anal and genitocrural regions. It is slowly progressive and persistent, but is without disturbing symptoms other than occasional slight itching. [Illustration: Fig. 75. Microsporon Minutissimum x 1000. (_After Riehl._)] Treatment, which is rapidly effective, is the same as that employed in tinea versicolor. #Dhobie Itch.# Dhobie itch is a name used in certain tropical countries to designate a somewhat peculiar itching eruption of the genitocrural and axillary regions, and by some also a similar eruption about the feet. It consists of a dermatitis of variable degree, usually with a festooned, irregular border, with considerable itching. It is believed that such cases are variously due to the trichophyton of ringworm, to the microsporon furfur of tinea versicolor, to the microsporon minutissimus of erythrasma, and to other parasites. #Actinomycosis.# #Describe actinomycosis.# Actinomycosis of the skin is an affection due to the ray fungus, and characterized by a sluggish, red, nodular, or lumpy infiltration, usually with a tendency to break down and form sinuses. The affection may involve almost any part, but its most common site is about the jaw, neck, and face. As a rule, the first evidence is a hard subcutaneous swelling or infiltration, which may increase slightly or considerably. The overlying skin gradually becomes of a sluggish or dark-red color. Softening ensues, and the diseased area breaks down at one or more points, from which there oozes a discharge of a sero-purulent, purulent, or sanguinolent character. In this discharge can be usually noted minute, friable, yellowish or yellowish-gray bodies representing conglomerate collections of the causative fungus. The course of the malady is commonly slow and insidious. Unless systemic pyemic infection occurs or the fungus elements find their way to the deeper organs or structures the general health remains apparently undisturbed. #What is the treatment?# The administration of moderate to large doses of potassium iodide, conjointly with curetting or excision of the diseased mass. Local applications of iodine solution can also be tried. #Blastomycetic Dermatitis.# #What do you understand by blastomycetic dermatitis?#