母斑 is read as ぼはん (bohan) and means nevus.
ぼはん
bohan
はは
mother
かあさん
ぼし
mother and child
ぼいん
vowel
ははおや
ははかた
maternal (grandfather, uncle, etc.)
ぼたい
mother's body (esp. when pregnant or after giving birth)
womb
ぼせい
motherhood
ぼこく
one's home country
ぼこくご
language of one's country
ぼにゅう
mother's milk