PNL2 (PNL2)
Anti-PNL2 is a novel monoclonal antibody, which has recently been introduced as an immunohistochemical reagent to stain melanocytes and tumors derived therefrom. Anti-PNL2 yields a strong cytoplasmic staining of skin and oral mucosal melanocytes, and staining of granulocytes when used at high concentration. Anti-PNL2 labels intraepidermal nevi while the dermal component of compound nevi are largely non-reactive with anti-PNL2. Antibodies against PNL2, Melan-A and HMB-45 stain most clear cell sarcoma cells and a few cells in angiomyolipomas and lymphangioleiomyomatosis. Non-melanocytic lesions found to be positive with this marker include PEComas and melanotic schwannoma. Anti-PNL2 is a useful antibody for the identification of melanomas and clear cell sarcomas. Differential diagnosis is aided by the results from a panel of antibodies, including antibodies against HMB-45, MART-1, Tyrosinase, and MiTF. The differential diagnosis between benign nevi and malignant melanoma is sometimes difficult, and malignant melanoma may mimic other neoplasms, such as undifferentiated carcinoma, sarcoma or large cell lymphoma. Anti-PNL2 may be most useful because of its high sensitivity for metastatic melanoma (87%), as opposed to 76% for anti-HMB-45 and 82% for anti-MART-1. Furthermore, anti-PNL2, combined with antibodies against S-100 and HMB-45 is a highly sensitive and specific marker for mucosal melanoma.