Tā shuāi le yī jiāo, tuǐ shàng chūxiàn le yīkuài zǐbān.
He took a fall and a bruise appeared on his leg.
Tips
usage
Everyday 紫斑 means a bruise (synonym 瘀青). In medical use it also means purpura - small purple skin patches caused by bleeding under the skin, as in 血小板减少性紫斑 'thrombocytopenic purpura'.