Case 10 - Discussion

Uploaded: 2007-01-15, Updated: 2007-06-22
   
 

Pilomatricoma / pilomatrixoma
 

  • Benign tumor of the skin of the head and neck region.

  • Usually found before the age of two

  • Stony-hard pea-sized lump under the skin.

  • The slowly growing tumor is made up of hair precursor cells, hence the name pilo- (hair) -matrix- (as in a generative matrix) -oma (tumor), and becomes calcified.

  • Pseudoencapsulated mass in deep subepiderms composed mainly of irregular islands of epithelial cells. The epithelial cells are organized in a characteristic biphasic architectural pattern with keratinized ghost cells in the center surrounded by variable amounts of peripheral basaloid cells. Basaloid cells exhibit deeply staining basophilic nuclei, which often contain small nucleoli. The keratinized ghost cells in the center have lost their nucleus and thus have a central unstained area. They are removed surgically and do not grow back.