Hibernoma
| Hibernoma | |
|---|---|
 |
|
| Micrograph of a hibernoma. H&E stain. | |
| Classification and external resources | |
| Specialty | oncology |
| ICD-10 | D17 (ILDS D17.950) |
| ICD-O | 8880/0 |
A hibernoma is a benign neoplasm of vestigial brown fat. The term was originally used by Gery in 1914.
This lesion has been called a fetal lipoma, lipoma of embryonic fat or a lipoma of immature fat.
Patients present with a slow-growing, painless, solitary mass, usually of the subcutaneous tissues. It is much less frequently noted in the intramuscular tissue. It is not uncommon for symptoms to be present for years. Benign neoplasm with "BROWN FAT" is noted
In general, imaging studies show a well-defined, heterogeneous mass, usually showing a mass which is hypointense to subcutaneous fat on magnetic resonance T1-weight images. Serpentine, thin, low signal bands (septations or vessels) are often seen throughout the tumor.
From a macroscopic perspective, there is a well-defined, encapsulated or circumscribed mass, showing a soft, yellow tan to deep brown mass. The size ranges from 1 to 27 cm, although the mean is about 10 cm.
The tumors histologically resemble brown fat. There are four histologic types recognized, but one is the most frequently seen (typical). There is a background of rich vascularity.
Hibernoma (intermediate magnification).
Oil red O-positive droplets of cytoplasmic lipid can be seen in most cases
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.
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.
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.
...
Wikipedia