The usefulness of c-Kit in the immunohistochemical assessment of melanocytic lesions

  • L. Pilloni | University of Cagliari, Italy.
  • P. Bianco University of Cagliari, Italy.
  • E. DiFelice University of Cagliari, Italy.
  • S. Cabras
  • M.E. Castellanos University Rey Juan Carlos, Spain.
  • L. Atzori University of Cagliari, Italy.
  • C. Ferreli University of Cagliari, Italy.
  • P. Mulas Hospital Businco, Cagliari, Italy.
  • S. Nemolato University of Cagliari, Italy.
  • G. Faa University of Cagliari, Italy.


C-Kit (CD117), the receptor for the stem cell factor, a growth factor for melanocyte migration and proliferation, has shown differential immunostaining in various benign and malignant melanocytic lesions. The purpose of this study is to compare c-Kit immunostaining in benign nevi and in primary and metastatic malignant melanomas, to determine whether c-Kit can aid in the differential diagnosis of these lesions. c-Kit immunostaining was performed in 60 cases of pigmented lesions, including 39 benign nevi (5 blue nevi, 5 intradermal nevi, 3 junctional nevi, 15 cases of primary compound nevus, 11 cases of Spitz nevus), 18 cases of primary malignant melanoma and 3 cases of metastatic melanoma. The vast majority of nevi and melanomas examined in this study were positive for c-Kit, with minimal differences between benign and malignant lesions. C-Kit cytoplasmatic immunoreactivity in the intraepidermal proliferating nevus cells, was detected in benign pigmented lesions as well as in malignant melanoma, increasing with the age of patients (P=0.007) in both groups. The patient’s age at presentation appeared to be the variable able to cluster benign and malignant pigmented lesions. The percentage of c-Kit positive intraepidermal nevus cells was better associated with age despite other variables (P=0.014). The intensity and percentage of c-Kit positivity in the proliferating nevus cells in the dermis was significantly increased in malignant melanocytic lesions (P=0.015 and P=0.008) compared to benign lesions (compound melanocytic nevi, Spitz nevi, intradermal nevi, blue nevi). Immunostaning for c-Kit in metastatic melanomas was negative. Interestingly in two cases of melanoma occurring on a pre-existent nevus, the melanoma tumor cells showed strong cytoplasmatic and membranous positivity for c-kit, in contrast with the absence of any immunoreactivity in pre-existent intradermal nevus cells. C-Kit does not appear to be a strong immunohistochemical marker for distinguishing melanoma from melanocytic nevi, if we consider c-Kit expression in intraepidermal proliferating cells. The c-Kit expression in proliferating melanocytes in the dermis could help in the differential diagnosis between a superficial spreading melanoma (with dermis invasion) and a compound nevus or an intradermal nevus. Finally, c-Kit could be a good diagnostic tool for distinguishing benign compound nevi from malignant melanocytic lesions with dermis invasion and to differentiate metastatic melanoma from primary melanoma.



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Author Biographies

M.E. Castellanos, University Rey Juan Carlos
Department of Mathematics and Informatics
L. Atzori, University of Cagliari
Department of Dermatology
C. Ferreli, University of Cagliari
Department of Dermatology
P. Mulas, Hospital Businco, Cagliari
UO of Dermatology
S. Nemolato, University of Cagliari
Department of Cytomorphology, Division of Pathology
G. Faa, University of Cagliari
Department of Cytomorphology, Division of Pathology
Original Papers
Supporting Agencies
c-Kit, melanoma, nevi
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How to Cite
Pilloni, L., Bianco, P., DiFelice, E., Cabras, S., Castellanos, M., Atzori, L., Ferreli, C., Mulas, P., Nemolato, S., & Faa, G. (2011). The usefulness of c-Kit in the immunohistochemical assessment of melanocytic lesions. European Journal of Histochemistry, 55(2), e20.

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