Closed-cell acne is commonly found on the face, and the neck is not a good place for closed-cell acne. Lesions similar to closed-cell acne on the neck may be flat warts, folliculitis, and other diseases. 1. flat warts: if the neck skin infected with human papillomavirus, can cause the skin to appear with the skin color of the flat pimples, mildly elevated, smooth surface, usually no self-conscious symptoms. 2. Folliculitis: due to bacterial infection of hair follicles with Staphylococcus aureus and other bacteria, it can cause the appearance of small pimples on the neck similar to closed mouth acne, accompanied by local redness, swelling, pain and other symptoms. If abnormal skin growths appear on the neck, you need to go to the hospital in time, clarify the cause of the disease, and standardize the treatment under the guidance of the doctor.