Histopathology. 2018 Sep 21. doi: 10.1111/his.13758. [Epub ahead of print]
Neurofilament is Superior to Cytokeratin 20 in Supporting Cutaneous Origin for Neuroendocrine Carcinoma.
Stanoszek LM1, Chan MP1,2, Palanisamy N3, Carskadon S3, Siddiqui J1, Patel RM1,2, Harms KL2, Lowe L1,2, Fullen DR1,2, Harms PW1,2.
Abstract
AIM:
Primary cutaneous neuroendocrine carcinoma, or Merkel cell carcinoma (MCC), cannot be distinguished morphologically from small cell neuroendocrine carcinomas (SmCC) from other sites. Immunohistochemistry is required to confirm cutaneous origin, and is also used for detection of sentinel lymph node (SLN) metastases of MCC. Cytokeratin 20 (CK20) expression is commonly used for these purposes, but is negative in some MCC cases, and has unclear specificity. We evaluated immunohistochemistry for neurofilament and CK20 in MCC compared with SmCC from other sites.
METHODS AND RESULTS:
We evaluated neurofilament expression in 55 MCC specimens from 39 unique patients, including 9 CK20-negative MCC tumors. Neurofilament expression was observed in 42/55 (76.4%) MCC cases, including 7/9 (77.8%) CK20-negative MCC cases. Neurofilament was expressed in 9/12 (75%) Merkel cell polyomavirus-positive tumors and 5/10 (50%) virus-negative tumors. Compared to a standard immunohistochemical panel (cytokeratin cocktail and CK20), neurofilament was 87.5% sensitive for detecting SLN metastases. Neurofilament and CK20 expression was also assessed in 61 extracutaneous SmCC from 60 unique patients, with primary sites including lung (27), bladder (18), cervix (3), gastrointestinal tract (3), sinonasal tract (2), and other sites (7). The specificity of neurofilament and CK20 for MCC versus non-cutaneous SmCC was 96.7% and 59.0%, respectively.
CONCLUSIONS:
Neurofilament has superior specificity to CK20 in distinguishing MCC from non-cutaneous SmCC. Neurofilament is frequently expressed in CK20-negative and virus-negative MCC tumors. Limitations of neurofilament immunohistochemistry include lower sensitivity than CK20 and subtle staining in some tumors. However, our findings indicate neurofilament is useful for excluding non-cutaneous SmCC. This article is protected by copyright. All rights reserved.
This article is protected by copyright. All rights reserved.
KEYWORDS:
Merkel cell carcinoma; Merkel cell polyomavirus; cytokeratin 20; neuroendocrine carcinoma; neurofilament; sentinel lymph node; small cell carcinoma
- PMID:
- 30239030
- DOI:
- 10.1111/his.13758
