Table 1.

Summary of the Histomorphological and Immunohistochemical Features of the Mucinous Cystic Neoplasm Described in the Case Report

Histomorphology	MCN with abundant ovarian-type stroma (confirmed by positive ER/PR) with extensive high-grade dysplasia.
	Microscopic foci of invasive adenocarcinoma budding off the main epithelial lining.
	Multiple hypercellular areas, comprising markedly atypical cells without glandular differentiation.
	Atypical cells appear spindled or rhabdoid with eccentrically placed nuclei and dense purple cytoplasm.
Immunohistochemistry	SMA, desmin, myogenin, CD10, and INI1 are negative in the hypercellular areas, arguing against a diagnosis of sarcoma.
	Pancytokeratin and CK 7 are strongly and diffusely positive in the hypercellular areas, including the spindled and rhabdoid-appearing cells. EMA is weakly positive in the same population of cells. This staining pattern is most consistent with undifferentiated carcinoma (anaplastic carcinoma).

CK, cytokeratin; EMA, epithelial membrane antigen; ER, estrogen receptor; MCN, mucinous cystic neoplasm; PR, progesterone receptor; SMA, smooth muscle actin.