Primary cutaneous signet-ring cell melanoma: a clinico-pathologic and immunohistochemical study of two cases

Am J Dermatopathol. 2003 Oct;25(5):418-22. doi: 10.1097/00000372-200310000-00007.


Signet-ring cell malignant melanoma is a rare histopathologic variant of malignant melanoma with only a few described cases. We report the clinical, histopathological, and immunohistochemical features of two cases of primary cutaneous signet-ring cell malignant melanoma. Neoplastic melanocytes showed abundant clear cytoplasm compressing the nuclei to the periphery, sometimes resulting in a signet-ring appearance. Immunohistochemically, neoplastic melanocytes in both cases expressed immunoreactivity for the usual melanocytic markers S-100 protein and Melan-A, although only the second case resulted HMB-45 positive. We review the literature about this rare cytologic variant of malignant melanoma and discuss the differential diagnosis with other cutaneous neoplasms that may show a signet-ring cell appearance of their neoplastic cells.

Publication types

  • Case Reports
  • Review

MeSH terms

  • Aged
  • Biomarkers, Tumor / analysis
  • Carcinoma, Signet Ring Cell / diagnosis
  • Diagnosis, Differential
  • Female
  • Humans
  • Immunohistochemistry
  • Male
  • Melanocytes / chemistry
  • Melanocytes / pathology*
  • Melanoma / chemistry
  • Melanoma / pathology*
  • Melanoma / surgery
  • Middle Aged
  • Skin Neoplasms / chemistry
  • Skin Neoplasms / pathology*
  • Skin Neoplasms / surgery
  • Treatment Outcome


  • Biomarkers, Tumor