Extra-uterine epithelioid trophoblastic tumour

Pulmonary extra-uterine epithelioid trophoblastic tumour

Definition

Extra-uterine epithelioid trophoblastic tumour is a type of gestational trophoblastic neoplasm comprising chorionic-type intermediate trophoblastic cells presenting as a lung tumour.

Epidemiology

Pulmonary involvement is most often seen in patients with widespread disseminated epithelioid trophoblastic tumour. Presentation with purely pulmonary disease is exceedingly rare.

Clinical features

Patients are women under the age of 50 years. They may have raised serum bHCG (which may also occur with pulmonary carcinomas).

Histopathology

They may have a nested architecture. The periphery of the tumour is composed of epithelioid mononuclear cells with pink cytoplasm, large nuclei and prominent nucleoli. Centrally, the nests are hypocellular. There are interspersed multinucleate cells with rightly eosinophilic cytoplasm, which may resemble syncytiotrophoblast. There may be dense eosinophilic material resembling keratin.

Immunohistochemistry


	AE1/AE1	2/21
	Cam5.2	1/11
	CK18	1/11
	EMA	1/11(patchy)
	Inhibin	2/21
	HPL	3/31
	HCG	3/31
	PLAP	0/11
	TTF-1	0/21
	S100	0/11
	p63	1/11
	MIB-1	from 10% to over 60% of cells1

Differential diagnosis

Primary pulmonary non-small cell carcinoma:

squamous carcinoma: affects smokers, older patients, express CK5/6 but lack CK18, CD10 and HSD3B1 expression
pleomorphic carcinoma: often show an inflammatory infiltrate, particularly of neutrophils; may express TTF-1; there may be a squamous cell or adenocarcinomatous component
primary or metastatic "atypical" choriocarcinoma with intermediate trophoblastic proliferation: this may occur after chemotherapy; the proliferation rate commonly exceeds 70%.

References

1 Lewin SN, Aghajanian C, Moreira AL, Soslow RA. Extrauterine epithelioid trophoblastic tumors presenting as primary lung carcinomas: morphologic and immunohistochemical features to resolve a diagnostic dilemma. Am J Surg Pathol. 2009 Dec;33(12):1809-14.