Pulmonary adenocarcinoma with enteric differentiation, PAED

Adenocarcinomas with enteric differentiation have been reported from the sinonasal tract and urinary bladder as well as from the lung.

Histopathology

PAED are characterised by the presence of columnar absorptive cell with brush borders, goblet and Paneth cells, comprising the majority of the tumour. These tumours are characterised by heterogeneity, but diagnosis on small biopsies is problematic.

Immunohistochemistry, with metastatic colorectal carcinoma and usual pulmonary adenocarcinoma for comparison

	Pulmonary adenocarcinoma with enteric differentiation	Metastatic colorectal carcinoma	Usual pulmonary adenocarcinoma
CDX-2	5/7 (2 cases more than 50% positive, 3 cases 5-50% positive)1	14/14 (all cases more than 50% positive)1	1/30 (1 case 5-50% positive)1
CK7	7/7 (all cases more than 50% positive)1	0/141	30/30 (29 cases more than 50% positive, 1 case 5-50% positive)1
CK20	3/7 (1 case more than 50% positive, 2 cases 5-50% positive)1	12/14 (all 12 cases more than 50% positive)1	0/301
TTF-1	3/7 (2 cases more than 50% positive, 1 case 5-50% positive)1	0/141	28/30 (27 cases more than 50% positive, 1 case 5-50% positive)1
SP-A	1/7 (1 case 5-50% positive)1	0/141	23/30 (13 cases more than 50% positive, 10 cases 5-50% positive)1
Napsin A	0/71	0/141	27/30 (all 27 cases more than 50% positive)1
MUC2	3/7 (3 cases 5-50% positive)1	8/14 (4 case more than 50% positive, 4 cases 5-50% positive)1	0/301

The expression of CDX-2, CK20 and MUC2 tends not to be coordinated, but to occur in different foci. Positivity for CK7 is retained. Tumour positivity for CK7 needs to be distinguished from entrapment of non-neoplastic pulmonary tissue.

Differential diagnosis

• Metastatic colorectal carcinoma

References

¹ Inamura K, Satoh Y, Okumura S, et al. Pulmonary adenocarcinomas with enteric differentiation: histologic and immunohistochemical characteristics compared with metastatic colorectal cancers and usual pulmonary adenocarcinomas. Am J Surg Pathol 2005; 29:660-5

This page last revised 18.7.2005.

©SMUHT/PW Bishop