Adenocarcinoma variants

(A) This colloid adenocarcinoma contains a cystic component surrounded by a fibrous wall that is filled with pools of mucin (M); such a pattern was previously called mucinous cystadenocarcinoma. The surface of the fibrous wall is lined by well-differentiated cuboidal or columnar mucinous epithelium (arrows).
(B) Colloid adenocarcinoma consists of abundant pools of mucin (M) growing within and distending airspaces. Focally well-differentiated malignant mucinous glandular epithelium (arrows) grows along the surface of fibrous septa and within the pools of mucin.
(C) Tumor cells (T) can sometimes be seen floating in the pale mucin.
​(D) Fetal adenocarcinoma consists of malignant glandular cells growing in tubules and papillary structures. These tumor cells have prominent clear cytoplasm, and squamoid morules are present.