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Stromal micropapillary pattern predominant lung adenocarcinoma - a report of two cases

Miki Ohe124*, Tomoyuki Yokose1, Yuji Sakuma3, Sachie Osanai1, Chikako Hasegawa1, Kota Washimi1, Kimitoshi Nawa2, Tetsukan Woo2, Rurika Hamanaka2, Haruhiko Nakayama2, Yoichi Kameda1, Kouzo Yamada2 and Takeshi Isobe4

Author Affiliations

1 Department of Pathology, Kanagawa Cancer Center, Kanagawa, Japan

2 Department of Thoracic Oncology, Kanagawa Cancer Center, Kanagawa, Japan

3 Molecular Pathology and Genetics Division, Kanagawa Cancer Center Research Institute, Kanagawa, Japan

4 Division of Clinical Oncology and Respiratory Medicine, Department of Internal Medicine, Shimane University Faculty of Medicine, Shimane, Japan

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Diagnostic Pathology 2011, 6:92  doi:10.1186/1746-1596-6-92

Published: 29 September 2011


Generally, adenocarcinomas with micropapillary pattern, featuring small papillary tufts lacking a central fibrovascular core, are thought to have poor prognosis. This pattern has been described in various organs. However, tumor cells with micropapillary pattern of lung adenocarcinoma are more often seen to float within alveolar spaces (aerogenous micropapillary pattern, AMP) than in fibrotic stroma like other organs (stromal micropapillary pattern, SMP) and SMP predominant lung adenocarcinoma (SMPPLA) has not been well described yet. We presented two cases of SMPPLA which were found in the last four years. Both the cases showed more than 50% of SMP in the tumor area. The majority of the stromal micropapillary clusters expressed MUC1 and epithelial membrane antigen along the outer surface of cell membrane. On the other hand, connective tissues surrounding stromal micropapillary clusters showed no reactivity for epithelial markers (thyroid transcription factor-1 and cytokeratin) or endothelial marker (D2-40 and CD34). It means clusters of SMP do not exist within air space or lymphatic or vessel lumens. The tumors with SMP often presented lymphatic permeation and vessel invasion, and intriguingly, one of the two cases showed metastasis to the mediastinal lymph node. Additionally, both the cases showed EGFR point mutations of exon 21. These results suggest that SMPPLA might be associated with poor prognosis and effective for EGFR tyrosine kinase inhibitors.

lung adenocarcinoma; micropapillary subtype; stromal micropapillary pattern; aerogeneous micropapillary pattern