Lipoid-cell urothelial carcinoma

Definition

A rare variant of urothelial carcinoma in which tumour cells resemble lipoblasts. This subtype is mentioned in the 2004 WHO classification.

Histopathology

The lipoid cell component represents a variable proportion of the tumour, usually up to 50%, the remainder being conventional urothelial carcinoma. The lipoid cell have multiple optically clear vacuoles, which may indent the nuclei. Nuclei are hyperchromatic and may have eosinophilic nucleoli. Rarely, the lipid cells are intermixed with plasmacytoid cells1,2. PAS and Alcian blue are negative.

Immunohistochemistry

	Cytokeratin	1/12
	CK 7	5/51
	CK20	4/51
	EMA	5/51 , 1/12
	S-100	0/51 , 0/12

Differential diagnosis

Signet ring cell carcinoma: the vacuoles are filled with mucin, positive for PAS and Alcian Blue. There is often also extracellular mucin.
Liposarcoma is extremely rare in the bladder. It is negative for EMA and cytokeratins.
Carcinosarcoma may include a liposarcomatous component.
Plasmacytoid carcinoma
Clear cell urothelial carcinoma; the cells are clear but not vacuolated, containing glycogen.
Microcystic urothelial carcinoma: the individual cells are not vacuolated.

Prognosis

These are aggressive high grade tumours.

References

1 Leroy X, Gonzalez S, Zini L, et al. Lipoid-cell variant of urothelial carcinoma: a clinicopathologic and immunohistochemical study of five cases. Am J Surg Pathol 2007; 31:770-3

2 Soylu A, Aydin NE, Yilmaz U, et al. Urothelial carcinoma featuring lipid cell and plasmacytoid morphology with poor prognostic outcome. Urology 2005; 65:797

This page last revised 6.6.2007.