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Embryoma of the kidney has been classified under various titles according to the predominant cell found at microscopic examination. For this reason it is important to define clearly what is meant by this term. We consider embryoma of the kidney as a highly malignant tumor peculiar to infancy and early childhood. It originates in the kidney and is of probable congenital origin. The tumor grows rapidly at times and assumes enormous proportions. Metastasis takes place by direct extension through its capsule, by the regional lymphatics or by the blood stream to the lung or brain. On gross appearance the tumor is a large encapsulated, grayish white mass encroaching on some portion of the kidney and destroying a greater or lesser part of it by pressure. The remaining portion of the kidney is divided from the tumor by a connective tissue capsule, but it cannot be dissected free from it. Occasionally,
William E. Ladd (Sat,) studied this question.