Fan, male, 74 years old. He came to the clinic with “rust-colored spots and plaques on the right lumbar region for more than 1 year. The histopathology was characterized by dense lymphocytic infiltration in the superficial dermis with capillary dilation and erythrocyte spillage. Diagnosis: golden moss. The rash was treated with topical halomethasone ointment and retinoic acid cream, and gradually shrank and flattened. General information: Fan, male, 74 years old. Chief complaint: rust-colored spots and plaques on the right lumbar area for more than 1 year. History: Rust-colored spots appeared on the right lumbar region more than 1 year ago without any obvious cause, and the scope gradually expanded and the lesions gradually elevated into plaques. No treatment was given. Previous history of hypertension, diabetes mellitus, hyperlipidemia and chronic bronchitis. Personal history and family history were not special. Specialized examination: rust-colored spots and plaques on the right side of the waist, ranging from about 3.5×3 cm in size, with clear borders, fused and elevated in the middle, with spots on the edges, and mild moss-like changes on the surface, with a small amount of scaling. No discoloration by pressure, no tenderness (picture). Histopathology: slight epidermal hyperkeratosis with focal hyperkeratosis and partial epidermal thickening. Dense lymphocyte infiltration in the form of bands was seen in the superficial dermis, and capillary dilation and erythrocyte extravasation were seen. Auxiliary examinations: blood and stool routine were normal. In biochemistry, high blood glucose and high triglycerides, the rest were normal. Diagnosis: golden yellow moss. Treatment: topical halomethasone ointment and retinoic acid cream. 2 months later, the rash shrank and flattened. 3 months later, the rash shrank and flattened further. Discussion: Yellow moss is also known as purpuric moss. The disease has the following characteristics: (1) it is mostly seen in adolescents; (2) it occurs in the lower extremities, with a restricted distribution, often banded or segmental; (3) the lesions are mossy plaques, papules or macules, which can be solitary or multiple, scattered or fused, and can be golden, bronze or dark brown, and can resemble petechiae; (4) there are mostly no conscious symptoms; (5) the disease has a chronic course, often persistent, and can progress slowly or last for many years A few lesions may fade on their own l-10 years after the onset of the disease. The etiology of this disease is unknown, and it is thought to be a form of pigmented purpura dermatosis, which belongs to lymphocytic peritubular capillaritis. Differential diagnosis: other pigmented purpuric dermatoses, lichen planus, fixed drug rash, traumatic hematoma, and negative pressure aspiration damage. Treatment: topical glucocorticoid cream, oral treatment with vitamin C, anaphylatoxin and compound lutin, PUVA, l% pimecrolimus cream topical.