Search

In the light of two cases of benign schwannomas of the tongue, including one particularly large tumour, the authors review the clinical and histological features and natural history of these tumours. Their rarity may explain the limited knowledge concerning these tumours and the long interval prior to treatment, resulting in technical difficulties due to their volume. Surgical enucleation is generally easy to perform. The prognosis is excellent after resection, as malignant transformation is exceptional.

Pigmented melanomas were induced in the Syrian golden hamster by oral administration of 9, 10-dimethyl 1,2-benzanthracene. The primary tumors were grafted into new animals to obtain a series of transplantable tumors. The grafted tumors show the malignant characters which are not present in the primary tumors. These were studied clinically, histologically and ultrastructurally. We believe that this transformation occured perhaps as a consequence of the selection of cells which have a more prominent tendency toward malignancy. This selection could be explained by a greater resistance of lesser pigmented melanocytes or by their weak immunologic capacity. The malignant potential of these cells could eventually be correlated with the presence of viral particles which act as cocarcinogens.