Causes of irregular moles on a child’s hand include melanoma, pigmented nevus, tinea cruris, and warts. 1. Melanoma: Melanoma is the most dangerous type of skin cancer. When irregular moles or moles change in shape or color appear on your child’s skin, you need to be alert to this condition and should consult dermatology department as soon as possible for further clarification. 2. Pigmented nevus: pigmented nevus formed by benign proliferation of melanocytes, which can also appear as irregular nevus on the palm of the hand. 3. Ringworm: When the palm of the hand is infected by fungi, these fungi will stimulate the proliferation of melanocytes, and irregular moles will also appear. 4. Warts: due to the infection of human papilloma virus, irregular moles can appear after these viruses stimulate the proliferation of skin cells. If you have irregular moles on your child’s hands, please go to the dermatology department of the hospital as soon as possible to get a clear diagnosis and follow the doctor’s instructions for treatment.