Infundibulocystic,isthmic structures, sebaceous ducts and sebocytes often coexist.Immunohistochemically a "zonal" pattern produced by expression of CK5/6, CK 5/8 eCAM 5.2 on the peripheral germinative cells contrasting with the absence ofstaining at the cell balls is typical and may be helpful in distinguishingtrichogerminoma from the more classic nodular types of trichoblastoma. The gene discussed is KRT5; the disease is trichoblastoma.