at least three of them connected to the overlying epidermis are related to the outer root sheath or trichilemma : the tumor of follicular infundibulum ( mehregan & butler 1961 ) and the inverted follicular keratosis ( helwig 1955 ) or follicular poroma ( duperrat & mascaro 1963 ) have been related to the infundibulum , the tricholemmoma ( headington & french 1961 ) to the lower outer root sheath .
C0346006
the tumor of follicular
C0221964
outer root sheath