Black hard lumps growing on the calves need to be carefully observed for the appearance of the hard lumps. If the hard bumps are densely arranged in a sheet-like distribution on the back of the calf, and obvious keratinization and hyperplasia can be felt by touching with the hand, and accompanied by strong itching, it is considered that the skin amyloidosis on the back of the calf may be possible. Related to long-term friction, irritation or skin specific degeneration, you can choose to use compound lactic acid cream, with fluticasone propionate cream for comprehensive treatment, you can also choose to use liquid nitrogen freezing but the damage to the skin is relatively large. If the black hard bumps growing on the legs have obvious roots and paroxysmal itching, consider that it may be nodular itchy rash. It is the papular urticaria caused by mosquito bites, and later after repeated friction and stimulation, the formation of the variability of the reaction, you can choose to direct liquid nitrogen freezing treatment.