Tyrosinase is a key enzyme involved in
the initial stages of melanin biosynthesis. Studies have shown Tyrosinase to be
a more sensitive marker when compared to HMB45 and MART-1. It has also shown to
label a higher percentage of desmoplastic melanomas than HMB45.
MART-1 (M2-7C10 + M2-9E3) recognizes a
protein of 18kDa, identified as MART-1 (Melanoma Antigen Recognized by T cells
1). MART-1 is a useful addition to melanoma panels as it is apparently specific
for melanocytic lesions. Studies have also shown that MART-1 is more sensitive
than HMB45 when labeling metastatic melanomas. This MART-1 does not stain
steroid tumors unlike Melan A .
S100 stains Schwannomas, ependymomas,
astrogliomas, almost all benign and malignant melanomas and their metastases.
S100 protein is also expressed in the antigen presenting cells such as the
Langerhans cells in skin and interdigitating reticulum cells in the paracortex
of lymph nodes