Teaching Case

Our patient is a 21-year-old male patient who was referred from our otorhinology OPD with nasal obstruction & headache. Examination revealed normal external facial & neurologic examination with no evidence of pituitary insufficiency. Soft, nodular mass was seen in nasopharynx on local examination.

Lateral skull radiograph showed vertically elongated sella and obliteration of nasopharyngeal air-column.

 Computed tomography(CT) showed a well-defined soft tissue density lesion with both lipomatous and ossific components within in midline, arising from a well-corticated defect in midline sphenoid bone with maximum diameter of 8 mm and extending into the nasopharynx. The solid component showed enhancement. There was no evidence of encephalocele.

 Magnetic resonance image confirmed CT findings. A vertically elongated cerebrospinal fluid-filled empty sella was seen, with thin and tight infundibulum in midline, extending from the hypothalamus and through the persistent hypophyseal canal, ending into the nasopharyngeal mass. The pituitary gland was not seen separately. There was no evidence of suprasellar mass lesion / other malformations.

Endoscopic endonasal transsphenoidal tumour decompression was done, tissue diagnosis was benign mature teratoma.

Craniopharyngeal canal (CPC) represents a rare congenital skull base defect with small canals seen in 0.42% of the asymptomatic population [1]. It is a remnant of Rathke’s pouch through sphenoidal synchondrosis, extending from the floor of sella turcica in the midline and connecting pituitary fossa with the nasopharynx cavity. The most common location is the vomer sphenoid junction.

The majority of these are asymptomatic and rarely are a source of neoplasia. The sac containing ectopic hypophysis has been reported by a few investigators [2].

We present a case with the persistent hypophyseal canal, and ectopic pituitary teratoma in the nasopharynx. To our knowledge, our patient is the first reported case with this association.

Aetiology is unknown; some authors have reported maternal use of anticonvulsants [3].

Embryological theories for persistent CPC:

           •          Remains of hypophyseal stalk [4-6].

           •          A residual channel in cartilage that has become bordered by bone [7].

           •          The remnant of a vascular channel formed during osteogenesis [8].

           •          Related to transsphenoidal meningoencephalocele [9].

Histological demonstration of normal and adenomatous pituitary tissue in CPC argues strongly in favour of pituitary origin and thus a remnant of Rathke’s pouch [5,6]

Classifications:

            •          The small CPC or hypophyseal channel - maximum width of 15 mm [3].

            •          The large CPC or transsphenoidal channel - more commonly associated with other craniofacial abnormalities [3].

The classification [5] mentioned in Figure 12 plays a crucial role in preventing iatrogenic complications, such as post-surgical hypopituitarism.

The small CPC in our case can be categorised as type 3B.

It is seldom seen on skull films because of its size but is easily detected on CT. 

 Associations:

Persistent CPC is associated with cerebrospinal fluid rhinorrhoea, meningitis,  panhypopituitarism, accidental removing of hypophysis mimicking a midline nasal polyp & hydrocephaly [4]; Rathke´s cleft cyst [10], infrasellar craniopharyngioma [11], holoprosencephaly [12], cephalocele [13], sphenoid teratoma [14], ectopic pituitary tissue [15], hyperprolactinaemia [16], hypothalamic hamartoma [16], corpus callosal dysgenesis [3] and other anomalies of skull base.

 Duplication of the pituitary gland with oropharyngeal teratoma, cleft palate, and other craniofacial abnormalities are associated, termed "syndrome of pituitary duplication - plus" [17].

 Outcome:

 Approaches to repair of CPC include transcranial, transoral–transpalatal and transsphenoidal endoscopic, with some controversy regarding the choice of approach [18]. Our patient was treated with the transsphenoidal endoscopic approach with a good outcome.

Prognosis depends on the size of the canal and associated anomalies. 

 Written informed patient consent for publication has been obtained.