Adenosquamous carcinoma of the lung

Definition

A tumour showing both squamous and adenocarcinomatous differentiation, with each component constituting at least 10% of the tumour.

Epidemiology

Up to 4% of lung carcinomas are of adenosquamous type1,2,3,5. The tumour is more common in men4 and here is a strong association with smoking4.

Radiology

Most tumours are peripheral.

Histopathology

The two components may be distinct or intermingled, may be obvious on H/E sections or may require mucin stains. A large cell component may be present. Amyloid may be present in the stroma.

Immunohistochemistry

See immunohistochemistry of malignant epithelial tumours of lung.

	AE1/AE3	positive
	Cam5.2	positive
	KL1	positive
	CK7	positive
	CK20	negative
	EMA	positive
	TTF-1	positive in the adenocarcinomatous component only

Differential diagnosis

Squamous carcinoma with entrapped lung tissue.
Adenocarcinoma with entrapped metaplastic squamous epithelium.
Mucoepidermoid carcinoma: is centrally located. Low grade mucoepidermoid carcinoma identical to the salivary gland equivalent with only mild atypia. High grade mucoepidermoid carcinoma is harder to differentiated, but is favoured by a central endobronchial location, the presence of a low grade mucoepidermoid component and absence of keratin pearl formation.

Prognosis

The prognosis is inferior to that for either squamous cell carcinoma or adenocarcinoma1,2,5,6.

References

0Tumours of the Lung, Pleura, Thymus and Heart. WHO Classification of Tumours. IARC Press 2004.

1Naunheim KS, Taylor JR, Skosey C, et al. Adenosquamous lung carcinoma: clinical characteristics, treatment, and prognosis. Ann Thorac Surg 1987; 44:462-6

2Fitzgibbons PL,Kern WH Adenosquamous carcinoma of the lung: a clinical and pathologic study of seven cases. Hum Pathol 1985; 16:463-6

3Ishida T, Kaneko S, Yokoyama H, et al. Adenosquamous carcinoma of the lung. Clinicopathologic and immunohistochemical features. Am J Clin Pathol 1992; 97:678-85

4Sridhar KS, Bounassi MJ, Raub W, Jr., et al. Clinical features of adenosquamous lung carcinoma in 127 patients. Am Rev Respir Dis 1990; 142:19-23

5Takamori S, Noguchi M, Morinaga S, et al. Clinicopathologic characteristics of adenosquamous carcinoma of the lung. Cancer 1991; 67:649-54

6Ruffini E, Rena O, Oliaro A, et al. Lung tumors with mixed histologic pattern. Clinico-pathologic characteristics and prognostic significance. Eur J Cardiothorac Surg 2002; 22:701-7

This page last revised 29.3.2005.