Childhood absence epilepsy (CAE), is one of the most frequent pediatric epilepsy syndromes. CAE is an idiopathic generalized epilepsy that occurs in otherwise normal children. The only seizure type at the time of diagnosis is the typical absence seizure. CAE is a well-known pediatric epilepsy syndrome affecting 10–17% of all children with epilepsy. It was previously known as pyknolepsy. The word pyknolepsy originates from the Greek piknoz (picnós), which means recurrent or grouped. The usual age of onset of CAE is between 4 and 10 years, with peak between 5 and 7 years.The typical absence seizure has a sudden onset of altered awareness and ends also abruptly. Electroencephalogram demonstrate characteristic "typical 3Hz spike-wave" generalized rhythmic discharges that begin and end abruptly. Prognosis is generally good with fair rates of response to treatment and with most patients growing out of their absencese. However, learning difficulties and seizure occurrence rates remain higher than the general population even after several years. When typical absence seizures start the age of 8– 9 years old when the absence seizures are infrequent or when the absence seizures are observed in a patient that had experienced a generalized tonic-clonic seizure, a diagnosis of juvenile absence epilepsy should be considered. Signs and symptoms
CAE is characterized by the presence of absence seizures. The absence seizures are usually brief (about 4 to 30 seconds) but occur frequently, usually around a dozen per day but sometimes even hundreds of times per day.
Myxoid variant: Loose, basophilic matrix, with thick fibrous septa, and foamy histiocytes
Lipoma-like variant: Univacuolated lipocytes, with only isolated hibernoma cells
Spindle cell variant: Spindle cell lipoma combined with hibernoma

Histochemistry
Oil Red O-positive droplets of cytoplasmic lipid can be seen in most cases

Immunohistochemistry
The neoplastic cells are S100 protein positive (approximately 80%), and show membrane and vacuole CD31 immunoreactivity. Uncoupling protein 1 (UCP1), a unique brown fat mitochondrial protein, is also positive. Cytogenetics
There are structural rearrangements of 11q13-21, which are considered most characteristic. This alteration can be detected by metaphase fluorescent in situ hybridization (FISH). MEN1 gene (11q13.1) is most frequently deleted, while GARP gene (11q13.5) may also be involved. Cytology
The fine needle aspiration smears show small, round, brown fat-like cells, with uniform, small cytoplasmic vacuoles and regular, small, round nuclei. There is usually a rich vascular background of branching capillaries. It is not uncommon to also have mature fat cells. Differential diagnoses
It is important to separate hiberoma from adult rhabdomyoma, a granular cell tumor and a true liposarcoma. Classification
This lesion has been called a fetal lipoma, lipoma of embryonic fat or a lipoma of immature fat. Management
Complete surgical excision is the treatment of choice, associated with an excellent long term clinical outcome. Epidemiology
The tumor is rare, affecting adults in the 4th decade most commonly. Patients are usually younger than those who present with a lipoma. There is a slight male predominance. Hibernoma are most commonly identified in the subcutaneous and muscle tissue of the head and neck region (shoulders, neck, scapular), followed by thigh, back, chest, abdomen, and arms.