Calcifying nested stromal-epithelial tumour of the liver

Calcifying nested stromal-epithelial tumour of the liver, CNSET

Definition

A rare hepatic tumour comprising islands of epithelial-spindle cells surrounded by a dense (myo)fibroblastic stroma associated with calcification/ossification.

Synonymns

Ossifying stromal-epithelial tumour, ossifying malignant mixed epithelial and stromal tumour of the liver, desmoplastic nested spindle cell tumour of the liver, nested stromal-epithelial tumour of the liver.

Epidemiology

This is predominantly a tumour of young women.

Clinical features

Some patients have associated Cushing syndrome which remits after resection1.

Radiology

Some patients have a history of calcified hepatic lesions from childhood.

Macroscopic appearances

The tumours most often occur in the right lobe of the liver. They are well-demarcated and multinodular.

Histopathology

There are islands of bland cells which vary from round to spindle, small to large. The stroma is desmoplastic. Mitoitc rate are up to 5 per 10 HPF. Calcification is present as psammoma bodies or ossification. Ductular proliferation (CK7 positive) is seen at the margins of the tumour. There may be microscopic infiltration of the surrounding liver.

Immunohistochemistry

	WT1	7/71
	AE1/AE3/LP34	9/91
	Cam5.2	4/41
	CK5/6	1/11
	CK7	0/91
	CK8	3/31
	CK18	3/41
	CK19	4/71
	CK20	0/51
	EMA	2/71
	BerEP4	0/21
	SMA	7/71
	Vimentin	8/81
	Desmin	0/51
	HepPar1	0/81
	pCEA	0/5(canalicular)1
	AFP	0/71
	CD56	2/51
	Chromogranin	0/91
	Synaptophysin	0/71
	ACTH	0/51
	Leu7	0/41
	NSE	3/31
	S100	1/91
	HMB45	0/71
	CD34	0/51
	PR	2/61
	ER	0/61
	TTF-1	0/31
	CD99	0/71
	CD117	2/71

Ultrastructure

Cytogenetics

There is negativity for EWS-WT1, Ewing/PNET and SYT-SSX fusion transcripts1.

Differential diagnosis

Desmoplastic small round cell tumour: most common in adolescent males, aggressive behaviour, lack calcification, positive for desmin, show EWS-WT1 fusion transcript
Ewing sarcoma/PNET: positive for CD99, shows EWS/PNET fusion transcript. CNSET has also been reported to show pseudorosette formation
Mixed epithelial and mesenchymal hepatoblastoma / teratoid hepatoblastoma: may also include bone / osteoid: positive for HepPar1 and AFP
Synovial sarcoma: shows SYT-SSX fusion transcript
GIST: may also be positive for CK8 and CK18 but also for CD34 and CD117
Sarcomatoid carcinoma
Metastatic primitive gonadal stromal tumour: positive for inhibin and PR

Management

Surgical resection.

Prognosis

The malignant potential of this tumour is uncertain and is currently considered a low grade malignancy.