Background

Craniopharyngioma is a rare malformational tumor of low histological malignancy, and two primary subtypes have been recognized (adamantinomatous and papillary) as yet. It originates from the remnants of Rathke’s pouch and mainly occurs in sellar-suprasellar region [1]. However, some rarely distant spread had been reported. This ectopic recurrence mainly disseminates along the surgical approach or via the cerebrospinal fluid (CSF) pathway. In this study, we report two cases of ectopic recurrence craniopharyngioma and make a literature review for the published similar case reports to introduce some experience with the management of ectopic recurrence craniopharyngioma. All the patients consented to the procedure.

Case presentation

Case 1

A 49-year-old female patient initially complained of vision loss and nausea in 2005. A sellar lesion had been detected and subtotally resected by craniotomy. The lesion was histologically determined to be an adamantinomatous craniopharyngioma. As supplementary therapy, the patient received gamma-knife treatment in 3 months and 12 months after operation. In 2012, the patient suffered severe nausea and vomiting again. The MR scan displayed tumor recurrence in the sellar region, with a cystic lesion extend to the right frontal lobe (Fig. 1A). These two lesions had been simultaneously resected through a transcranial surgery (Fig. 1B), and the pathology showed both were adamantinomatous craniopharyngioma (Ki-67 = 3%). However, in 2021, it had been found tumor recurrence in the sellar region; even worse, there was a new isolated lesion in the right frontal lobe (Fig. 1C). She received tumor resection therapy via the same transcranial approach (Fig. 1D), and the pathological staining confirmed the adamantinomatous craniopharyngioma with Ki-67 2% (Fig. 1E).

Fig. 1
figure 1

MRI, CT scans, and pathological features of case 1. A Preoperative MRI showed a cystic solid lesion in the sellar-suprasellar region extending to the right frontal lobe in 2012. B Postoperative CT scan showed total resection of the right frontal lesion. C MRI scan showed tumor recurrence in both the sellar-suprasellar region and the right frontal lobe in 2021. D Postoperative CT scan showed total resection of the two lesions. E The pathological features showed typical morphology of adamantinomatous craniopharyngioma

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Case 2

A 63-year-old female patient suffered from bilateral vision loss for 6 months before the first diagnosis as craniopharyngioma in 2017. The patient received a subtotal resection of the tumor by craniotomy in other hospital. Her vision had partially recovered after operation. However, in 2019, the patient felt vision loss again, while the MR scan showed the tumor had recurred not only in the initial site but also in the right temporal lobe with a 1.2 × 0.9-cm lesion (Fig. 2A). Due to the small lesion volume and lack of related symptoms, this patient decided to resect the tumor in the suprasellar region by transsphenoidal surgery firstly (Fig. 2B) and did a close follow-up to the right temporal lesion. One year postoperatively in 2020, the patient suffered serious symptoms like worse vision, bluntness, and drowsiness. The MR scan displayed tumor recurrence in the suprasellar region, and the right temporal lesion had enlarged (Fig. 2C). A craniotomy surgery was performed to resect both lesions and place an Ommaya catheter in the cyst (Fig. 2D). In 2021, unfortunately, the tumor relapsed rapidly (Fig. 1E). The pathology of both lesions was adamantinomatous craniopharyngioma (Fig. 2 F–G), with a higher Ki-67 index (5%) of the ectopic recurrence compared with that (3%) in initial site.

Fig. 2
figure 2

MRI, CT scans, and pathological features of case 2. A Preoperative MRI showed a cystic and solid lesion in the sellar-suprasellar region and a small lesion in the right temporal lobe in 2019. B CT scan after endoscopic transsphenoidal surgery. C MRI scan showed tumor recurrence with cyst in the suprasellar region and enlargement of the lesion in the right temporal lobe in 2020. D CT scan after transcranial surgery and Ommaya reservoir implantation. E MRI scan showed tumor recurrence again in the suprasellar region in 2021. F The pathological features of suprasellar lesion showed adamantinomatous craniopharyngioma. G The pathological features of right temporal lobe lesion also showed adamantinomatous craniopharyngioma

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Discussion

Craniopharyngioma is a benign epithelial tumor and accounts for 0.5–2.5 cases per 1 million population every year [2–4]. It originates from the sellar region, specifically the craniopharyngeal duct [1]. The main symptoms are caused by compression of adjacent tissues such as visual disturbance (optic nerve), endocrine disorder (pituitary gland), personality changes (hypothalamus), and hydrocephalus (third ventricle) [5, 6]. The primary therapy is surgical resection. However, due to the unpredictable growth pattern and involvement of critical anatomical structures, it is difficult to achieve total resection and apt to relapse.

Ectopic recurrence craniopharyngioma is rare. Up to date, only 61 patients with 63 cases had been described in the literature including our own [7–53] (Table 1). All the cases are exhibited by case reports; thus, it is difficult to make epidemiology statistics. According to previous studies listed in Table 1, the incidence of ectopic recurrence craniopharyngioma has been 0 ~ 4.7% and accounts for 7 ~ 20% of all recurrences approximately. As craniopharyngioma has a bimodal age distribution, with peak incidence rates observed in children aged 5–14 years and adult aged 50–74 years [54], the incidence of ectopic recurrence between children group and adult group has no significant difference based on our statistic. The onset age in children group and adult group ranges from 2–14 years old (6.70 ± 3.33) to 17–73 years old (40.63 ± 15.58), while the interval year between tumor initiation and ectopic recurrence ranges from 0.17–20 (7.28 ± 6.76) years to 0.3–34 (6.85 ± 7.29), respectively. There is no significant gender difference on ectopic recurrence. By reviewing the treatment history, achieving gross total resection seems not to prevent the ectopic recurrence during first operation. What’s more, 16 patients who received postoperative adjuvant radiotherapy still suffer from the ectopic recurrence. There is no accurate data about the long-term prognosis of ectopic recurrence due to the scarcity of clinical cases. According to current data, no recurrence was observed at a longest follow-up duration of 12 years [26]. But one patient died due to local recurrence in sellar region [35].

Table 1 The characteristics of ectopic recurrence craniopharyngioma
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The diameter of ectopic recurrence tumor ranges from 0.5 to 6.5 (3.14 ± 1.73) cm. The pathological results of ectopic recurrence craniopharyngioma demonstrate that the adamantinomatous type constituted the majority with the number of 36, while the papillary type accounted for only 4 cases and 20 cases’ pathology was unclear. The Ki-67 index of ectopic tumor does not show a remarkable increasement than that of initial tumor. The most common site of ectopic recurrence is frontal lobe, followed by cerebellopontine angle (CPA), temporal lobe, parietal lobe, and others. Currently, there are two views on the mechanism about ectopic recurrence, along the surgical approach and the CSF pathway. Transcranial surgery for craniopharyngioma via pterion is the most frequently used approach that can achieve sufficient surgical field and better protection of nerves and vessels. But it is believed that the tumor cells would disseminate or seed during the operation, and that is the reason why frontal lobe was the most common site of ectopic recurrence, so did the recurrence in Sylvian fissure. The ectopic recurrence mechanism of case 1 in our study belonged to this type. Ectopic recurrence in CPA, temporal and parietal lobe, and lumber space, which far from the surgical route, were considered as the dissemination of tumor cells via CSF pathway. That is the mechanism of case 2; the recurrence site in temporal lobe was far away from the primary surgical area. After statistical analysis, 35 ectopic recurrence cases were due to the seeding along the surgical approach, and 28 cases were due to the seeding via the CSF pathway.

Ectopic recurrence craniopharyngioma is rare, but it can lead to serious symptoms according the location such as hearing loss, disequilibrium, epilepsy, behavioral, and personality change. Thus, some delicate surgical procedure such as strictly separating the tumor by cottonoids, carefully aspirating the cystic fluid to avoid the contamination of CSF, and adequate irrigation in surgical field can help to reduce the risk of ectopic recurrence, and standardized follow-up can provide valuable information for treatment.