母斑 is read as ぼはん (bohan) and means nevus.
ぼはん
bohan
かあさん
mother
ぼし
mother and child
ぼいん
vowel
ははおや
いろは
かか
mommy
はは
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