Malignant transformation in craniopharyngiomas

Craniopharyngiomas are successfully managed with surgery and/or adjuvant chemoradiotherapy but have been documented to undergo malignant transformation (MT), albeit very rarely, with only 23 reported cases. The exact cause and pathogenesis of this MT are unknown, although the literature has suggested a possible correlation with radiotherapy.

To review the reported cases of malignancy, in particular looking at the incidence, tumor characteristics, previous treatment modalities, and median survival.

We conducted a PUBMED, SCOPUS, OVID SP, and INFORMA search with a combination of key words: craniopharyngioma, malignancy, transformation, neoplasm, radiation therapy, and anaplastic. We identified 23 cases relevant to our study.

Median age at the time of diagnosis of malignant craniopharyngiomas was 31 years (range, 10-66 years); 52.6% of the patients were female. Histologically, the most common tumor types were squamous cell carcinoma (80.96%), with adamantinomatous cell type being the most common morphology (89.47%). We found that 21.7% of the cases were diagnosed as malignant craniopharyngioma at first biopsy. Of the rest, the median time from initial benign diagnosis to MT was 8.5 years (range, 3-55 years). Median overall survival after MT was 6 months (range, 2 weeks-5 years). Using the Spearman rank correlation, we found no correlation between the use of radiation therapy (correlation coefficient, -0.25; P < .05) or its dosage (correlation coefficient, -0.26; P < .05) and MT.

Malignant craniopharyngiomas are rare and are associated with a poor prognosis. MTs occur years after the initial benign craniopharyngioma diagnosis and are associated with multiple benign craniopharyngioma recurrence. Results also show that, contrary to widespread belief, there is a poor correlation between radiotherapy and MT.