Well-differentiated malignant cylindroma with partially preserved hyaline sheaths. A locally invasive neoplasm?

Light microscopic and ultrastructural features of a well-differentiated malignant cylindroma are described. The tumor was locally invasive but it neither recurred nor metastasized during the 3 years after surgery. This fact, together with the similar biologic behavior of two previously described, well-differentiated malignant cylindromas, suggests that these tumors possess either low or no metastatic potential.