Signet Ring Cells

Signet Ring Cells

Signet ring cells are tumour cells of Extramammary Paget's disease seen in the epidermis where the nucleus is pushed to the edge by large amounts of cytoplasmic mucin within the cell. These cells are not seen in Mammary Pagets disease.

True Extramammary Pagets is derived from apocrine cells that are neoplastic. They usually just involve the epidermis and adnexal but not the dermis and only very rarely metastasise. In contrast in Pagets disease the tumour cells are those of the lactiferous ducts. They can invade the dermis and metastasise.

Extramammary Pagets from an underlying rectal, prostate or badder cancer are really epidermal invasion from contiguous  adenocarcinoma cells and these do not show the signet ring clue.