Page 157 - New epidemiological and PSMA-expression based paradigms in salivary gland tumors

The follow-up data of two nationwide series of pleomorphic adenoma was pooled with a focus on risk of malignant transformation and analyzed against the literature. The combined nationwide data (n=9,003 patients) showed 3.1% with 1st recurrence of which 6.2% were malignant. In the literature 1st recurrence rate was >7% at 20 years follow-up. Malignant transformation occurred in 0-7%, and facial nerve damage increased from with each surgery 3-16% at 1st recurrence to 18-30% at 2nd recurrence.
Recurrent pleomorphic adenoma showed a characteristic course with surgery being unreliable and damage to the facial nerve. The risk of malignant transformation was low. This might give flexibility towards a more conservative approach of management.
Chapter 4:
Supposed risk of malignant transformation of salivary gland pleomorphic adenoma is an important reason for aggressive retreatment in recurrent pleomorphic adenoma. However, although the diagnostic category “carcinoma ex-pleomorphic adenoma” suggests that malignant transformation of a pleomorphic adenoma is a regular event, this has until now not been shown to occur in sequential lesions of one patient. Here we show the molecular events in transformation to a malignancy of a pleomorphic adenoma of the parotid gland. Detailed molecular analysis revealed a LIFR/PLAG1 translocation characteristic for pleomorphic adenoma and next to this a PIK3R1 frameshift mutation and several allelic imbalances. In subsequent malignant recurrences the same LIFR/PLAG1 translocation, PIK3R1 frameshift mutation and allelic imbalances were present in addition to TP53 mutations.
This case thus not only shows the malignant transformation of pleomorphic adenoma but also demonstrates that molecular analysis can be of help to recognize malignancy in the rare case of recurrent pleomorphic adenoma.
Chapter 5:
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Calculation of the risk of a second primary tumor or malignant transformation after a benign primary tumor (e.g. a pleomorphic adenoma) is impossible in cohorts without central registration of follow-up, because the exit date (by death or international emigration) is unknown. Our aim was to develop and validate a method to address this problem.
We used a cohort with a tumor (similar to a benign primary tumor) with a high survival probability, that in contrast to benign tumors, did have follow-up data: basal cell carcinoma (BCC). In women with BCC, registered in the former Dutch Comprehensive Cancer Centre South Registry (1992-2012), the breast cancer risk
Summary
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