[Biochemical diagnoses of malignant melanomas with determinations of 5-S-cysteinyldopa in lesions]

To develop a biochemical diagnosis for malignant melanomas, 5-S-cysteinyldopa in the tissues of malignant melanomas and other pigmented tumors were quantitatively analysed. The mean 5-S-CD value from primary melanotic melanoma lesions was 202.4 ng/mg (80.6-821.4) and those of metastatic melanoma lesions was 214.0 ng/mg (96.2-520.0). There was no significant differences in these 5-S-CD values between the types of primary lesions. On the other hand, the 5-S-CD values from pigmented tumors other than melanomas, such as Spitz nevus, dysplastic nevus, pigmented basal cell epithelioma, and melanoepithelioma Bloch II were less than 55 ng/mg. From these results it is thought that pigmented tumors can be diagnosed as malignant melanomas, if the 5-S-CD values in the tissues are over 100 ng/mg. The mean 5-S-CD values of pigmented macules of SSM was 734.5 ng/mg (320.0-1666.3) and those of ALM was 1.8 ng/mg (0.7-3.6). These data suggest that the biochemical diagnoses of SSM in situ can be based on 5-S-CD values, the diagnoses of ALM in situ can not.