epithelial nest

ker·a·tin pearl

a focus of central keratinization within concentric layers of abnormal squamous cells; seen in squamous cell carcinoma. Synonym(s): epithelial nest, epithelial pearl, pearl (3) , squamous pearl

epithelial nest

(1) A nonspecific term for a circumscribed mass of epithelial (usually squamous) cells. 
(2) Keratin pearl, see there.