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. Characteristically there is a garland pattern of infiltration resembling that seen in colorectal adenocarcinomas with cystic glandular structures containing mucin and necrotic debris encircled by an array of round tubular glands. A cribriform 'gland in gland' pattern is present with lumina filled with necrotic epithelial cells, fibrin, neutrophils, and karyorrhectic debris, enmeshed in extracellular mucin giving an appearance of 'dirty necrosis', often accompanied by segmental necrosis of the glandular lining. The glands were lined by stratified tall columnar absorptive-like cells with modest amounts of apically oriented amphophilic cytoplasm. Their hyperchromatic nuclei were round to cigar shaped and oriented basally. Mitoses were frequent, including atypical forms. While extracellular diastase resistant periodic acid Schiff and mucicarmine-positive mucin is seen, goblet cells are less constant and may have a patchy distribution. Signet ring cells were not present. Focal clear cell change is sometimes seen, and there may be abundant mucin production. Squamous differentiation and papillae are not observed. Diagnosis on small biopsies may be 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	5/71, 0/62	14/14(all cases more than 50% positive)1, 10/102	1/30(1 case 5-50% positive)1
CK7	7/7(all cases more than 50% positive)1, 6/62, 1/13	0/141, 0/102	30/301
CK20	3/71, 0/13	12/14(all 12 cases more than 50% positive)1	0/301
TTF-1	3/71, 6/62, 1/13	0/141, 0/102	28/301
SP-A	1/7(1 case 5-50% positive)1	0/141	23/301
Napsin A	0/71	0/141	27/30(all 27 cases more than 50% positive)1
MUC1	1/62	3/102
MUC2	3/7(3 cases 5-50% positive)1, 1/6(<25% of cells in one case)2	8/141, 9/102	0/301
MUC5AC	2/6(<25% of cells in two cases)2	1/10(<25% of cells in one case)2

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

2 Yousem SA Pulmonary intestinal-type adenocarcinoma does not show enteric differentiation by immunohistochemical study. Mod Pathol 2005; 18:816-21 FULL TEXT

3 Maeda R, Isowa N, Onuma H, et al. Pulmonary intestinal-type adenocarcinoma. Interact Cardiovasc Thorac Surg 2008; 7:349-51 FULL TEXT

This page last revised 28.11.2008.