The "vanilla fudge" cyst.

A white cyst, partially covered by jet black splotches and streaks, had a surface appearance of vanilla fudge ice cream. Histologically, the cyst was lined with two distinctly different types of follicular epithelium--one identical to that of the infundibulum and the other to that of the matrix. The black pigment was melanin, produced by numerous dendritic melanocytes that were situated only in the region of the epithelium-resembling matrix.