The antibody to the
melanoma antigen recognized by T cells (anti-MART-1, clone M2-7C10) is a newly described antibody to a transmembrane
protein previously detected only in normal skin melanocytes,
retinal tissue, and
malignant melanoma (MM). This antibody is the basis for ongoing
immunotherapy protocols at the National Institutes of Health/National Cancer Institute. HMB-45, an antibody directed against a premelanosome
glycoprotein, although used predominantly for the diagnosis of MM, has shown consistent staining in
angiomyolipoma (AML),
lymphangiomyoma/
lymphangiomyomatosis (
LAM), and
clear cell sugar tumor (CCST), a group of
tumors proposed to be related on the basis of their common perivascular epithelioid cells, which exhibit various degrees of smooth muscle differentiation, melanogenesis, and intracytoplasmic membrane bound granules. To compare the immunoreactive patterns of anti-MART-1 with those of HMB-45, we performed
avidin-
biotin immunoperoxidase testing on nonmelanocytic
neoplasms (AMLs, LAMs, CCSTs) known to express HMB-45. Microwave pretreatment was necessary for anti-MART-1 staining on
paraffin-embedded material. Our results showed that all of the 10 cases of AML were immunoreactive for both anti-MART-1 and HMB-45; that all of the 4 cases of
LAM were positive for HMB-45, with 1 of the 4 reacting with anti-MART-1; and that 3 of the 4 cases of CCST expressed HMB-45, whereas 1 of the 4 was positive for anti-MART-1. Our findings lent additional support to previous studies that proposed a relationship between AML,
LAM, and CCST. Anti-MART-1 and HMB-45 share similar specificities for these nonmelanocytic
tumors, but the former seems to be a less sensitive marker for these lesions. In similar circumstances, anti-MART-1 and HMB-45 are potentially useful
clinical markers.