tā / shǒu bì / shàng / yǒu / yí kuài / tiān shēng / de / máo zhì / píng shí / bú tòng / bù yǎng

他手臂上有一块天生的毛痣，平时不痛不痒。

He has a congenital hairy nevus on his arm, which is usually painless and not itchy.