Aberrant anaplastic lymphoma kinase expression in high-grade pulmonary neuroendocrine carcinoma
- Harumi Nakamura1,
- Koji Tsuta1,
- Akihiko Yoshida1,
- Tatsuhiro Shibata2,
- Susumu Wakai1,
- Hisao Asamura3,
- Koh Furuta1,
- Hitoshi Tsuda1
- 1Department of Pathology and Clinical Laboratories, National Cancer Center Hospital, Tokyo, Japan
- 2Division of Cancer Genomics, National Cancer Center Research Institute, Tokyo, Japan
- 3Division of Thoracic Surgery, National Cancer Center Hospital, Tokyo, Japan
- Correspondence to Dr K Tsuta, Department of Pathology and Clinical Laboratories, National Cancer Center Hospital, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045, Japan;
- Received 2 November 2012
- Revised 15 March 2013
- Accepted 29 March 2013
- Published Online First 25 April 2013
Aims In lung cancer with anaplastic lymphoma kinase (ALK) gene rearrangement, accurate diagnosis is essential to identify patients who can be treated with a specific kinase inhibitor. Sensitive ALK immunostaining can provide nearly complete concordance with gene rearrangement status and is expected to serve as a surrogate biomarker for tailored treatment with an ALK inhibitor. In the present report, we describe aberrant ALK expression in a small proportion of pulmonary neuroendocrine carcinomas (NECs) that do not have ALK gene alteration.
Methods A total of 227 pulmonary NECs were assembled on tissue microarrays and were subjected to highly sensitive ALK staining methods.
Results We observed focal positivity with heterogeneous intensity in 2 (2.9%) of 69 small-cell carcinomas and 1 (0.9%) of 106 large-cell NECs. In contrast, 52 carcinoid tumours were all negative for ALK expression. Neither ALK rearrangement nor amplification was observed using fluorescence in situ hybridisation, and no somatic mutation was detected in three ALK positive NECs.
Conclusions Thus, this aberrant expression is probably of a wild-type ALK and a potential pitfall when implementing sensitive ALK immunohistochemistry in the molecular diagnosis of lung cancer.