Skin - Nonmelanocytic tumors
Carcinoma (non-adnexal)
Small cell neuroendocrine carcinoma

Author: Ghassan Tranesh, M.D. (see Authors page)
Editor: Hong Qu, M.D.

Revised: 13 October 2016, last major update November 2014

Copyright: (c) 2002-2016,, Inc.

PubMed Search: Small cell neuroendocrine carcinoma [title]

Cite this page: Small cell neuroendocrine carcinoma. website. Accessed October 17th, 2018.
Definition / general
  • Primary neuroendocrine carcinoma of the skin is a rare malignancy which presents most commonly on sun-exposed areas in late adulthood
  • Tumor typically metastasizes quickly with a fatal outcome
  • Metastases are usually found in skin (28%), liver (13%), bone (10%), brain (6%) (Postepy Dermatol Alergol 2014;31:325)
  • Mainly the elderly, more often men, usually between 65 and 85 years of age
  • Merkel cell carcinoma often arises in setting of immunodeficiency (post-transplant immunosuppression or HIV infection), autoimmune connective tissue disease and neoplasm, particularly Hodgkin disease, B cell lymphoma, chronic lymphocytic leukemia, breast and ovary cancer
  • Established risk factors for Merkel cell carcinoma development are UV radiation, immunosuppression and Merkel cell polyomavirus infection (Science 2008;319:1096)
Clinical features
  • Classic clinical presentation is a rapidly-growing, red to violaceous, firm, solitary nodule
Prognostic factors
  • Usually poor prognosis
  • Better prognosis if primary tumor < 2.0 cm, but this is uncommon

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Prognostic algorithm

Case reports
  • Wide surgical excision or Mohs micrographic surgery of tumor with sentinel lymph node biopsy (J Skin Cancer 2013;2013:189342)
  • Adjuvant radiotherapy or chemotherapy according to clinical staging
  • Metastases are treated with protocols similar to those for small cell lung carcinoma
Clinical images

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CT guided biopsy

Lower leg tumors

Cutaneous in-transit metastases

Gross description
  • Blue-red, hard and painful to the touch
Microscopic (histologic) images

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Various stains

CK20, Ki67

Positive stains