CLEAR-CELL SARCOMA OR MALIGNANT-MELANOMA OF SOFT PARTS - MOLECULAR ANALYSIS OF MICROSATELLITE INSTABILITY WITH CLINICAL CORRELATION

Malignant melanoma of soft parts, also termed clear cell sarcoma (CCS) , is a rare malignancy of neural crest origin which is different from cutaneous malignant melanoma. Although a translocation involving chrom osomes 22 and 22 is characteristic of clear cell sarcoma and not malig nant melanoma, there are a paucity of methods to differentiate the two . Therefore, a study of microsatellite instability (MIN) was undertake n to determine if mechanisms of DNA mismatch repair can differentiate these malignancies. MIN has been described in a variety of malignancie s including 25% of malignant melanomas. Paraffin-embedded neoplastic a nd non-neoplastic cells were obtained from Ii individuals (five males; six females; age range from seven to GO !years) with CCS. Isolated DN A was PCR amplified at 17 separate microsatellite loci using radioativ e-labeled primers. Tumor tissues was compared to normal tissue for eac h analysis. No MIN was detected. Loss of heterozygosity was detected i n only one patient at a single locus (IFNA). The lack of MIN in clear cell sarcoma further defines the distinction between this tumor and ma lignant melanoma. Clinically, local recurrence and metastasis were ind icators of poor outcome. The size of the tumor was not a significant p rognostic indicator. Local recurrence, satellitosis, or nodal metastas is was not proven to be uniformly fatal. Utilization of chemotherapy a nd/or radiation demonstrated no obvious survival advantage. The histol ogic parameters of mitotic rate and the presence of necrosis were not prognostic. Limb-preserving surgical procedures were as effective as a mputation for local disease control. The actuarial survival rate was c alculated to be 48% at five years. (C) Elsevier Science Inc., 1998.