Complejo Hospitalario Materno Insular de Gran Canaria. Spain. Servicio de Obstetricia y Ginecología.

Correspondence to: Andrés Arencibia Molina, Paseo de Lugo nº 16,  Piso Primero (3), Las Palmas de Gran Canaria, Apartado 35004. España.

Definition

Hypothalamic hamartoma is a congenital malformation consisting of heterotrophic or hyperplasic neuronal tissue located under the third cerebral ventricle contiguous with the hypothalamus and commonly associated with epileptic syndrome and precocious puberty (1).

The hypothalamic hamartomas are the most common cause of the central precocious puberty. Two distinct clinical groups exist. The first group is characterized by small sized hamartomas (less than 1.5 cm) causing the precocious puberty, the second group is characterized by larger hamartomas causing seizures, but the precocious puberty may be absent. An asymptomatic hypothalamic hamartomas are extremely rare (2).

Intra-hypothalamic and para-hypothalamic types of the hamartomas have been described. The intra-hypothalamic hamartomas are broadly attached to the hypothalamus and may distort the contours of the third ventricle. They seem to be associated rather with seizures than with precocious puberty. The para-hypothalamic hamartomas are pedunculated masses attached to the hypothalamus by a narrow base and these lesions seem to be rather associated with precocious puberty than with seizures (1, 2).

Case report

A solid mass was found within the fetal brain during ultrasound examination performed at 38 weeks of a pregnancy. The mass was located under the third cerebral ventricle and measured 25x23 mm. After birth a nuclear magnetic resonance (MRI) confirmed the diagnosis of hypothalamic hamartoma.

Images 1, 2: 38 weeks; the images represent transverse scans of the fetal head. An abnormal round mass of the hypothalamic hamartoma can be seen centrally (the lesion is depicted by the dashed line on the image 2).

Images 3, 4: 38 weeks; the images show transverse scans of the fetal head with the slightly hyperechoic round mass of the hypothalamic hamartoma that can be seen centrally.

Images 5, 6: MRI images showing the hypothalamic hamartoma.

Images 7, 8: The image 7 represents a drawing of the hypothalamus - the hypothalamus (in pink) is anteriorly and ventrally to thalamic structures. The anterior border of hypothalamus is made by the lamina terminalis (LT), the posterior border is formed by line between the mammillary bodies (MB) and posterior commissure (CP). The floor of the hypothalamus is formed by the infundibular stalk (IS), tuber cinereum (TC) and mammillaris bodies. The roof of the hypothalamus is bordered by an imaginary line between anterior and posterior commissures. CA - anterior commissure; OC - optic chiasm.  The image 8 depicts the hamartoma of the hypothalamic region.

Sonographic findings

Hypothalamic hamartomas present as a suprasellar solid mass within the thalami region of the brain.

Differential diagnosis

Gliomas, germ cell tumors. Hypothalamic hamartoblastomas are part of the Pallister-Hall syndrome.

Associated anomalies

Hypoplasia of the olfactory bulbs, absence of the pituitary gland, cardiac and renal anomalies, imperforate anus, craniofacial anomalies, syndactyly and short metacarpal.

Prognosis

The children with the hypothalamic hamartoma suffer with seizures, visual changes and precocious puberty in both sexes (3, 4).

Management

Antiepileptic drugs and gonadotropin-releasing hormone agonists are used in treatment of the accompanying symptoms of the hypothalamic hamartomas. (3, 4).

References

1. Poussaint, Tina Young. Magnetic resonance imaging of pediatric brain tumors: State of the Art. Topics in magnetic resonance imaging. Pediatric Neuroradiology, Part I, Vol 12(6), 411-433. December 2001.
2. Cheng Kan, Swamura Yukata, Yamauchi T et all. Asyntomatic large hypothalamic hamartoma associated with polydactilia in an adult. Neurosurgery, 32(3):458-460, March 1993.
3. Feuillan P, Jones JV, Barnes K et all. Reproductive axis after discontinuation of gonadotropin releasing hormone analog treatment of girls with precocious puberty: long term follow-up comparing girls with hypothalamic hamartoma to those idiopathic precocious puberty. J. Clin Endocrinol and metabolism. Vol 84, Nº 1, 44-49.1999.
4. Feuillan P, Jones JV, Barnes K et all. Boy with precocious puberty due to hypothalamic hamartoma: reproductive axis after discontinuation of gonadotropin releasing hormone analog therapy. J. Clin Endocrinol and metabolism. Vol 85, Nº 11, 4036-4038.2000.