CD56: a useful marker for diagnosing Merkel cell carcinoma.
BACKGROUND
Merkel cell carcinoma (MCC) of the skin is an aggressive but rare malignant neuroendocrine tumor. For its pathological diagnosis, we use a panel of immunohistochemical markers, such as cytokeratin 20 (CK 20), epithelial membrane antigen (EMA), chromogranin A, neuron specific enolase (NSE), synaptophysin, and Leu7 (CD57) to demonstrate its epithelial and neuroendocrine features. CD56, or neural cell adhesion molecule (NCAM), has been demonstrated recently as the tumor marker of the pulmonary neuroendocrine cell system. Its expression in MCC, however, has still rarely been investigated. Furthermore, in such very few previous studies on NCAM expression in MCC, all the tumor cells were not necessarily demonstrated to express NCAM.


OBJECTIVE
To study the immunoreactivity of CD56 in MCC, especially using a monoclonal antibody of a clone 1B6, different from those adopted in the previous reports.


METHODS
We reexamined CD56 expression immunohistochemically in five MCC cases, along with the conventional panel of markers described above, using paraffin-embedded tissue sections.


RESULTS
CD56 revealed the most diffuse and intense positive staining, which was noted along the cell borders, in all specimens compared with other neuroendocrine tumor markers.


CONCLUSIONS
The results of our study indicate that CD56, especially a new monoclonal antibody (clone 1B6), is a useful immunohistochemical marker for MCC.
Department of Dermatology, Miyazaki Medical College, 5200 Kihara, Kiyotake, Miyazaki 889-1692, Japan. mkurokawa@post1.miyazaki-med.ac.jp
Motoki
M
Kurokawa
Kazuki
K
Nabeshima
Yutaka
Y
Akiyama
Shunichi
S
Maeda
Takaaki
T
Nishida
Fumiko
F
Nakayama
Masahiro
M
Amano
Katsumi
K
Ogata
Mitsuru
M
Setoyama
D000368:Aged; D015703:Antigens, CD / Q000032:analysis; D014408:Biomarkers, Tumor / Q000032:analysis; D019002:CD56 Antigen / Q000032:analysis*; D015266:Carcinoma, Merkel Cell / Q000276:immunology / Q000473:pathology*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D019006:Neural Cell Adhesion Molecules / Q000032:analysis; D015203:Reproducibility of Results; D012878:Skin Neoplasms / Q000276:immunology / Q000473:pathology*
D015703:Antigens, CD; D014408:Biomarkers, Tumor; D019002:CD56 Antigen; D019006:Neural Cell Adhesion Molecules