Clinical Pearls & Morning Reports

Posted by Carla Rothaus

Published October 11, 2017


A search of the literature for syndromes in which linear growth and the energy level are preserved despite poor weight gain leads to Russell’s syndrome, which is also known as the diencephalic syndrome. Read the latest Case Records of the Massachusetts General Hospital.

Clinical Pearls

Q: What are some of the features of the diencephalic syndrome?

A: The diencephalic syndrome is an extremely rare cause of failure to thrive in infants and young children. Affected children present with profound emaciation, preserved linear growth, locomotor hyperactivity, and occasional euphoria, symptoms that all arise in association with a low-grade glioma of the hypothalamus. According to the National Organization for Rare Disorders, children with the diencephalic syndrome are profoundly emaciated but often appear very happy and outgoing; their behavior is in strong contrast to their physical appearance. In addition to hyperkinesis, the clinical presentation may include nystagmus, strabismus, and recurrent emesis.

Q: When do the symptoms associated with the diencephalic syndrome usually arise?

A: Symptoms of failure to thrive in children with the diencephalic syndrome typically arise during the first year of life. The diagnosis of the diencephalic syndrome, with identification of a hypothalamic glioma, is established at a median age of 18 months, approximately 12 months after the onset of failure to thrive.

Morning Report Questions

Q: How are young patients with the diencephalic syndrome treated?

A: Although focal radiotherapy is associated with excellent disease control, the use of radiation is usually avoided or deferred in young patients because of the risk of developing neurocognitive impairments, endocrinopathies, and vasculopathies. For these reasons, initial treatment for children with unresectable disease typically consists of chemotherapy. With the availability of a growing array of low-intensity chemotherapy options, multiple courses of chemotherapy with different agents are often offered to postpone or avoid delivery of radiotherapy in young children with disease progression.

Q: What are some of the characteristic histologic features of pilomyxoid astrocytoma?

A: Pilomyxoid astrocytomas most commonly occur in infants and young children and are frequently located in the region of the hypothalamus and optic chiasm. The tumor is characterized by bipolar cells in an angiocentric arrangement with a myxoid background. Rosenthal fibers and eosinophilic granular bodies, commonly found in standard pilocytic astrocytomas, are not typically found in pilomyxoid astrocytomas. The tumor is generally more aggressive and more prone to local recurrence and dissemination in cerebrospinal fluid than other forms of pilocytic astrocytoma, but the clinical course can vary.

Figure 2.  MRI of the Head.
Figure 3.  Biopsy Specimen of the Brain Tumor.

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