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Int J Clin Exp Pathol 2013;6(4):802-809

Case Report
Primary cutaneous neuroendocrine tumor (atypical carcinoid) ex-pressing KIT and
PDGFRA with myoepithelial differentiation: a case report with immunohistochemical and
molecular genetic studies

Tadashi Terada

Departments of Pathology, Shizuoka City Shimizu Hospital, Shizuoka, Japan

Received January 22, 2013; Accepted February 6, 2013; Epub March 15, 2013; Published April 1, 2013

Abstract: Primary cutaneous neuroendocrine tumors (NET) except for Merkel cell carcinoma have rarely been reported. Herein reported is a
very unique case of primary cutaneous NET with immunohistochemical markers of myoepitheliomas. A 47-year-old woman presented a tumor
measuring 0.8x0.9x0.6 cm of the face. The tumor was excised completely with wide margins. Morphologically, the tumor was located in the
dermis, and the tumor was composed of epithelioid cells arranged in trabecular, sinusoidal, rosette, ribbon-like, and cord-like patterns. Focal
areas show tubular formations. The tumor cells were homogenous, and their nuclei showed hyperchromasia but no apparent histological
features of malignancy were seen. The stroma was very scant. No invasive features were seen. Immunohistochemically, the tumor cells were
strongly positive for cytokeratin (CK) 34BE12, CD5/6, CK14, NCAM (CD56), p63, and KIT (CD117), and moderately positive for CK AE1/3, p53,
chromogranin, synaptophysin, neuron-specific enolase (NSE), PDGFRA, CA19-9, and Ki-67 antigen (labeling index=23%). The tumor cells
were negative for CK CAM5.2, CK7, CK8, CK18,CK19,CK20, EMA, vimentin, CEA, HMB45, S100 protein, α-smooth muscle antigen, desmin,
CD34, GFAP, neurofilaments, CD99 (MIC2), CD45, CD57, ErbB2, TTF-1, MUC1, MUC2, MUC5AC, and MUC6. Mucins examined by d-PAS and
Alcian blue techniques were negative. A genetic analysis using PCR-direct sequencing method in paraffin sections identified no mutations of
KIT (exons 9, 11, 13 and 17) and PDGFRA (exons 12 and 18) genes. Imaging modalities including CT and MRI identified no tumor in the body.
The clinicians thought that the tumor was cured. She was a sailor and immediately visited other countries; therefore the follow-up could not be
done. (IJCEP1301051).

Keywords: Skin, NET, carcinoid, neuroendocrine, myoepithelioma, immunohistochemistry, KIT, PDGFRA

Address correspondence to: Dr. Tadashi Terada, Department of Pathology, Shizuoka City Shimizu Hospital, Miyakami 1231 Shimizu-Ku, Shi-
zuoka 424-8636, Japan. Tel: +81-54-336-1111; Fax: +81-54-334-1173; E-mail: piyo0111jp@yahoo.co.jp