True about anaplastic thyroid carcinoma:a) Common in elderlyb) Well encapsulatedc) Will not invade surrounding structuresd) Distant metastasis commone) Some degree of differentiation to Papillary and Follicular types seen

About option 'e' Schwartz writes: "On gross inspection, anaplastic tumors are firm and whitish in appearance. Microscopically, sheets of cells with marked heterogeneity are seen. Cells may be spindle-shaped, polygonal, or large, multinucleated cells. Foci of more differentiated thyroid tumors, either follicular or papillary, may be seen, suggesting that anaplastic tumors arise from more well-differentiated tumors."