Spinal melanotic clear-cell sarcoma: a light and electron microscopic study.

We report a melanotic spindle-cell tumor that arose from a thoracic spinal nerve root and metastasized to both lungs. The bulk of the tumor consisted of glycogen-rich clear cells and bore a striking resemblance on light and electron microscopy to at least one variant of the clear-cell sarcoma of tendons and aponeuroses. The presence of schwannoma-like areas noted in the primary tumor on light microscopy and the formation of a highly developed basal lamina noted on ultrastructural examination suggest that the tumor may be a partially dedifferentiated malignant melanotic schwannoma. This tumor is discussed in the context of a simple histogenetic classification of melanotic tumors.