R Bergman1, L Malkin, E Sabo, H Kerner. 1. Department of Dermatology, Rambam Medical Center, Technion-Israel Institute of Technology, Haifa, Israel. dermatology@rambam.health.gov.il
Abstract
BACKGROUND: The histopathologic differential diagnosis of Spitz nevus (SN) from malignant melanoma (MM) may be difficult. OBJECTIVE: Our purpose was to determine the staining pattern and usefulness of MIB-1 antibody, which recognizes Ki-67 antigen in formalin-fixed, paraffin-embedded tissue, as an adjunct to the histopathologic differential diagnosis of SN. METHODS: Twenty-five compound SNs, 27 MMs, and 26 compound nondysplastic melanocytic nevi (MNs) were immunostained with the MIB-1 antibody. RESULTS: The mean counts of MIB-1--stained tumor cells of the epidermal and dermal components, both alone and together, were significantly lower in SNs and MNs than in MMs (P <.0001). The dermal counts showed the best discriminating power. In addition, the mean dermal/epidermal count ratios for MIB-1 in SNs and MNs (0.25 and 0.23, respectively) were significantly lower than the corresponding ratio (0.94) in MMs (P <.0001). CONCLUSION: MIB-1-stained tumor cell counts, especially of the dermal component, and dermal/epidermal MIB-1 count ratios may be helpful as an adjunct to the histopathologic differential diagnosis of SN.
BACKGROUND: The histopathologic differential diagnosis of Spitz nevus (SN) from malignant melanoma (MM) may be difficult. OBJECTIVE: Our purpose was to determine the staining pattern and usefulness of MIB-1 antibody, which recognizes Ki-67 antigen in formalin-fixed, paraffin-embedded tissue, as an adjunct to the histopathologic differential diagnosis of SN. METHODS: Twenty-five compound SNs, 27 MMs, and 26 compound nondysplastic melanocytic nevi (MNs) were immunostained with the MIB-1 antibody. RESULTS: The mean counts of MIB-1--stained tumor cells of the epidermal and dermal components, both alone and together, were significantly lower in SNs and MNs than in MMs (P <.0001). The dermal counts showed the best discriminating power. In addition, the mean dermal/epidermal count ratios for MIB-1 in SNs and MNs (0.25 and 0.23, respectively) were significantly lower than the corresponding ratio (0.94) in MMs (P <.0001). CONCLUSION:MIB-1-stained tumor cell counts, especially of the dermal component, and dermal/epidermal MIB-1 count ratios may be helpful as an adjunct to the histopathologic differential diagnosis of SN.