Late development of craniopharyngioma following surgery for Rathke's cleft cyst

Objective: Rathke's cleft cyst (RCC) may transform to papillary type craniopharyngioma (CP) after squamous metaplasia: this is referred to as ciliated CP. We encountered a case involving a patient who had late development of adamantinomatous CP following surgery for RCC, the details of which may shed light on the histogenesis of CP in general. Patient: A 41-year-old man presented to our institution with visual disturbance, and magnetic resonance imaging (MRI) showed a cystic mass in the suprasellar region. The patient underwent a biopsy via a transsphenoidal approach and was diagnosed as having a RCC. 34 months after the initial surgery, the patient revisited our hospital for a rapidly aggravating visual disturbance and underwent neuroendoscopic biopsy and tumor removal via a bifrontal craniotomy. Histologically, the tumor was shown to be an adamantinomatous CP. No nuclear β-catenin accumulation was detectable in the previous RCC specimen, but nuclear β-catenin accumulation was found in the recent CP specimen, restricted to whorl-like structures or surrounding ghost cells. Conclusions: Our case of adamantinomatous CPthat developed long after removal of the RCC, diagnosed by β-catenin staining, supports the hypothesis that CPs may develop from RCCs directly due to β-catenin mutations. However, it still does not prove that a histogenetic connection can be shown between the two lesions which are clonally unrelated. Our case is reported as two consecutive lesions; this in itself is a rare situation.