Cluster of teeth in brain - Pituitary teratoma an uncommon tumor in common location

Clinical History

A 7-year-old child presented with short stature. Lab investigations revealed growth hormone deficiency.

Imaging Findings

MRI Brain revealed a well encapsulated lesion in the sella with suprasellar extension filled with multiple non enhancing small teeth-like structures appearing hypointense on all sequences, bloomed on GRE with a central thin linear area appearing iso-intense on T1 and hyperintense on T2WIs. The minimal intervening soft tissue which appeared isointense on T1 and hyperintense on T2WIs and the capsule showed moderate contrast enhancement. The pituitary gland was not visualized separately from the lesion. Optic chiasm was minimally displaced superiorly and the interface with a cavernous segment of the bilateral internal carotid arteries was well maintained (figure 1-6).

Screening CT Brain showed a cluster of multiple teeth like structures in the sella with suprasellar extension. Most of them showed a root and pulp formation. Sella was thinned out and widened, however with no destruction (figure 7-11).

Discussion

A suprasellar tumour with a cluster of teeth is a rare presentation with only a few cases reported in the literature up to date. The differential diagnosis considered is mature teratoma and odontogenic craniopharyngioma.

Germ cell tumours in the brain are rare. Among different types of germcell tumours, teratomas contribute only 0.5% of all brain tumours. They originate from totipotential cells differentiating in to tissues of all three germ layers [1]. Teratomas commonly involve the midline structures like the pineal gland and posterior pituitary [2]. The age group of germ cell tumour appearance is 16-45, with a mean age of 16 years. There are three types of teratomas, namely mature (benign), immature and malignant. When the teratomas contain structures arising from all three germ cell layers like keratin, teeth, cartilage and fat they are considered benign [3].

Craniopharyngiomas comprise 6% to 10% of all brain tumours, being a more common suprasellar tumour than the teratomas. The common age group affected is the 1st and 2nd decade, with a second peak in 7th and 8th decades [4]. There are two types of craniopharyngiomas, the papillary type is commonly seen in adults and shows predominant solid components with less occurrence of calcifications. The adamantinomatous type is commonly seen in the paediatric age and appears as a mixed density lesion with areas of calcification and cystic change on imaging. Frank teeth formation has also been described in a few cases [5]. The presence of odontoid structures in craniopharyngiomas is explained by its embryological origin from primitive stomatodeum [5].
Clinically both of these lesions will present either with pituitary insufficiency features or with visual disturbance and raised intracranial pressure due to mass effect over the adjacent structures.
On imaging both of these lesions will appear as well encapsulated lesions in the suprasellar region. A cystic component, calcifications and teeth formation can be seen in either of them. Teratomas can show other germ cell layer structures like fat. In both of these conditions, the normal pituitary may not be visualized on imaging either due to compression/infiltration by the lesion. Hence the exact differentiation of these two entities only based on imaging features is challenging and histo-pathology (HPE) plays a confirmative role.
For both of these entities, complete surgical resection has shown good prognosis with less recurrence rate [3]. Complete resection of the tumour was performed in our patient and the HPE reports confirmed the diagnosis of mature pituitary teratoma.

Differential Diagnosis List

Final Diagnosis

Mature Pituitary teratoma.

URL:	https://eurorad.org/case/14314
DOI:	10.1594/EURORAD/CASE.14314
ISSN:	1563-4086