Pleomorphic adenoma: a preliminary histopathologic comparison between tumors occurring in the deep and superficial lobes of the parotid gland.

Twenty-four cases of pleomorphic adenoma of the parotid gland were retrospectively reviewed. The histopathological features of capsular thickness, penetration and completeness, tumoral cell population and mitotic activity were analyzed in twelve superficial lobe and twelve deep lobe tumors. The capsules were found to be significantly thicker and less likely to be penetrated by tumor in the deep lobe group. No significant differences in completeness of encapsulation, cell population or mitotic activity were found between the two groups. This may explain the clinical suggestion that the less aggressive surgical approach which is often performed does not compromise the prognosis for recurrence in the deep lobe lesions.