The Collaborative International Dictionary of English v.0.48:

Molluscum \Mol*lus"cum\, n. [NL. See Mollusk.] (Med.)
   A cutaneous disease characterized by numerous tumors, of
   various forms, filled with a thick matter; -- so called from
   the resemblance of the tumors to some molluscous animals.
   --Dunglison.
   [1913 Webster]

WordNet (r) 3.0 (2006):

molluscum
    n 1: any skin disease characterized by soft pulpy nodules