Comparison of melanoma antigen recognized by T cells (MART-1) to HMB-45: additional evidence to support a common lineage for angiomyolipoma, lymphangiomyomatosis, and clear cell sugar tumor.

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.