Cutaneous mucin deposition is a group of diseases characterized by diffuse or restricted deposits of mucin in the skin. The mucins of the dermis are found in the intercollagenous matrix, mainly hyaluronic acid and acidic mucopolysaccharides, and are mildly basophilic, granular or fibrous under HE staining. General pathological changes of skin mucin deposition: 1. The epidermis is approximately normal or atrophied and flattened. The dermal reticular layer has a large amount of restricted mucin deposits, and the collagen fibers are separated and replaced by mucin, becoming small cystic cavities. 3.Mucin deposition can be seen in the mucin deposition of more mucinoblast proliferation. 4, no collagen increase, no inflammatory cell infiltration. Clinical features: 1. Rarely seen in middle-aged people. 2, due to restricted proliferation of fibroblasts, producing excess mucin, which is deposited in the local tissues, as seen in multiple nigra syndrome. 3.The lesions are light red single or multiple papules or nodules, about 2cm in diameter, with smooth epidermis, and can be seen on any part of the body surface. 4, without any conscious symptoms, can be self-healing.