Itchy bumps at the base of the thighs may be caused by contact dermatitis, ringworm, eczema and other diseases. 1. contact dermatitis: clinical manifestations of erythema, swelling, and pimples, itching, etc., the rash can be distributed in all parts of the body, and the cause of its formation may be related to exogenous substances in contact with the skin. 2. Ringworm: ringworm may be caused by red fungus and other dermatophytes invading the skin, commonly found in the groin, buttocks and other places, the skin will appear erythema, flaking and pimples and other symptoms. 3. Eczema: Eczema patients may have erythema, papules, itching, oozing and other symptoms, commonly found on the head and face, hands and feet and limbs. The cause may be immune, genetic and endocrine factors. There are many reasons for the itchy thighs, so it is recommended that the patient consult a doctor to clarify the cause.