Black patches on the waist are generally considered to be related to pigmented gross epidermal nevus, coffee spots, fixed drug rash, etc., and need to be analyzed specifically according to the symptoms.
1. Pigmented nevus of hairy epidermis: it is a kind of acquired pigmented patch or mildly elevated papule, usually with increased hair on the surface of the lesion. This disease mostly appears in childhood or around puberty, and often occurs after exposure to the sun.
2. Café au lait: Café au lait is a well-demarcated hyperpigmented spot, sometimes combined with multiple neurofibromas. Most of them exist at birth or soon after birth. With the growth of age, the damage can be enlarged and the number can be increased.
3. Fixed drug rash: limited skin damage caused by allergy to sulfa drugs, somatropin and other drugs, manifested as the waist skin inflammation subsides, leaving local gray-brown patchy deposits.
If the patient appears to have black patches on the skin of the waist, it is recommended to go to the dermatology department of the regular hospital to find out the cause and follow the doctor’s instructions for treatment.