Polysialylated neural cell adhesion molecule as a marker for differential diagnosis in pediatric tumors

Background/Purpose: Some malignant pediatric tumors express the polysialylated form of the neural cell adhesion molecule (PSA-NCAM), which normally becomes restricted to a few regions of neural plasticity and regenerating nerve tissue after embryogenesis. Recently, serum concentrations of polysialylated NCAM have been shown to be tumor associated in children with rhadbomyosarcoma and neuroblastoma. This study was undertaken to evaluate polysialylated NCAM as a marker helpful in distinguishing between various embryonal tumors and other lesions suspicious of a malignancy. Methods: Fresh frozen specimens from examplary tumors of the thorax, adrenal glands, and kidneys of 17 children were investigated immunohistochemically by the Alkaline Phosphatase anti-Alkaline Phosphatase (APAAP) technique. Simultaneously, the patients' serum was investigated by a chemiluminescent immunoassay, which likewise used the polysialic acid-specific monoclonal antibody 735. Results: Serum concentrations correlated with the expression of PSA-NCAM in immunohistochemistry. They were elevated in children with PSA-NCAM-positive tumors as alveolar rhabdomyosarcoma, undifferentiated neuroblastoma, and anaplastic Wilms tumor, but negative in all other patients. Conclusion: PSA-NCAM serves as a useful marker for differential diagnosis during workup of tumros suspicious of a malignant neoplasm.