Itchy scrotum and a pimple on the scrotum may be caused by atopic dermatitis, scrotal inflammation, scrotal eczema, etc., and you should consult a doctor in time to clarify the cause. 1. Allergic dermatitis: Allergic dermatitis is an allergic reaction of the skin caused by allergic substances. Allergic dermatitis mainly manifests itself in a variety of lesions, such as erythema, pimples, pustules, cracks, as well as oozing, scabbing and so on. 2. Scrotal inflammation: scrotal inflammation refers to the infection of the scrotal skin and subcutaneous, common causative organisms are Staphylococcus aureus, Pseudomonas aeruginosa, etc. In addition, scrotal injury, urinary extravasation, diabetes mellitus, and other pathologic factors may also cause scrotal inflammation. Patients with scrotitis may show redness and swelling of the skin at the scrotum, itching, and accompanied by scrotal pain, rashes, blisters and so on. 3. Scrotal eczema: scrotal eczema is a common type of eczema, the cause of which is still unclear, and may be related to infectious factors, mental factors, endocrine factors. Scrotal eczema patients may manifest as scrotal itching, and the scrotum found pimples or small blisters. If you feel unwell, you should go to the hospital in time to avoid delaying the condition or causing adverse reactions.