Qualification In Immunohistochemistry (QIHC) Practice Exam

This item tests which markers are included in a Pan-Mel + S100 panel used in melanoma workups. The panel combines melanocytic differentiation markers with a highly sensitive melanocytic marker to confirm melanocytic lineage in tumors. Tyrosinase and MART-1 (Melan-A) are specific indicators of melanocytes and melanoma cells, while S100 is a very sensitive marker for melanocytic cells, often staining in melanoma even when other markers are negative. The combination of these three provides a strong, complementary signature for melanoma, which is why the option listing Tyrosinase, MART-1, and S100 best fits the Pan-Mel + S100 panel and matches the typical staining notes (cytoplasmic for Tyrosinase and MART-1, and nuclear/cytoplasmic for S100). The other choices bring in markers not used in this panel (such as CK7/CK20, which are epithelial markers, or Ki-67, a proliferation marker) or omit a key melanocytic marker, making them less appropriate for identifying melanocytic origin.