Mycosis fungoides, first noted by a French physician in1806, is a rare type of lymphoma, reports Stanford School of Medicine. Lymphomas are cancer of the lymphoid system. Mycosis fungoides may appear on the skin in many ways, including erythroderma, thin red patches and raised thick skin.
As of 2015, the cause of mycosis fungoides is unknown, notes Stanford School of Medicine. Making a correct diagnosis during the early stages of this condition is difficult. It may be mistaken for other skin conditions, such as chronic dermatitis or psoriasis. Doctors diagnose mycosis fungoides by evaluating the patient’s medical history, conducting a physical exam and obtaining a skin biopsy, states Lymphoma Research Foundation.