Contributed by Elia Guadagno, Domenico Solari, Sara Pignatiello, Teresa Somma, Roberta Sgariglia, Gennaro Ilardi, Paolo Cappabianca, Marialaura Del Basso De CaroFINAL DIAGNOSIS
Papillary craniopharyngioma with dysplastic changes.
DISCUSSION
Craniopharyngioma is a benign epithelial tumor that represents 1.2-4.6% of all intracranial tumors and with two clinicopathologic subtypes, the adamantinomatous and the papillary. The former is more common, affects with bimodal age distribution, is more prone to recurrence and is characterized by CTNNB1 mutation in 95% of cases. The papillary variant is less common, usually occurs in adults, often arise in supratentorial and third ventricular regions and shows BRAF V600E mutations in 81-95% (1). Rarely craniopharyngiomas may show malignant transformation and it usually involves adamantinomatous forms (2).
Morphologic criteria of malignancy are not clear. According to the previous literature, at least three of the following features should be present: cellularity and increased nuclear-cytoplasmic ratio, nuclear pleomorphism and hyperchromatic nuclei, increased mitotic activity or higher Ki67 expression, coagulative necrosis and other histologic features such as solid growth pattern, destruction of basement membrane, infiltrative growth and microvascular proliferation (3).
For years it was believed that malignant transformation was due to radiation exposure; however, it was shown that there is a poor correlation between the two (4), and some cases of malignant craniopharyngioma de novo or not associated with previous radiotherapy were described. Minimally invasive surgery aiming to achieve a "maximum allowed" removal combined with adjuvant radiotherapy is nowadays the most widely used option for the treatment of craniopharyngioma. In the present case, after the failure of endoscopic endonasal surgery, the occurrence of hydrocephalus hindered the second procedure scheduled for removal and the eventual radiotherapy.
The present case is peculiar because of atypical morphology shown especially by the second specimen. This severe cytological atypia has never been described in a case of papillary craniopharyngioma. No other criteria of malignancy were satisfied beyond pleomorphism, so we could consider this aspect as a form of dysplastic changes that could be explanatory of its biological aggressiveness (30% volume increase in 6 months).
REFERENCES
Contributed by Elia Guadagno, Domenico Solari, Sara Pignatiello, Teresa Somma, Roberta Sgariglia, Gennaro Ilardi, Paolo Cappabianca, Marialaura Del Basso De Caro
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