Fetal Brown Fat Research Articles

Hibernoma mimicking a lipoma: A case report of a rare benign tumor

Hibernomas are rare, benign soft tissue tumors developed from fetal brown fat [1]. They account for around 1.6% of benign lipomatous tumors and present as progressive, slow-growing, painless subcutaneous masses [2]. Hibernomas resemble lipomas in their clinical behavior, but their unique imaging and histopathologic features may aid in differentiating them from each other [1]. We report a case of a 19-year-old Emirati woman who presented with painful lower back swelling for one year. The lesion was excised, and the histopathology revealed a diagnosis of hibernoma. The patient had an uneventful postoperative course and was discharged on the second postoperative day. The management approach of hibernomas varies as per the symptoms, our patient was managed with surgical intervention whereas asymptomatic patients can be observed. Surgical resection is the definitive treatment. No local recurrence has been reported.

Maternal High-Fructose Intake Activates Myogenic Program in Fetal Brown Fat and Predisposes Offspring to Diet-Induced Metabolic Dysfunctions in Adulthood.

Excess dietary fructose intake is a major public health concern due to its deleterious effect to cause various metabolic and cardiovascular diseases. However, little is known about the effects of high-fructose consumption during pregnancy on offspring metabolic health in adulthood. Here, we show that maternal consumption of 20% (w/v) fructose water during pregnancy does not alter the metabolic balance of offspring with a chow diet, but predisposes them to obesity, fatty liver, and insulin resistance when challenged by a high-fat diet. Mechanistically, diet-induced brown fat reprogramming and global energy expenditure in offspring of fructose-fed dams are impaired. RNA-seq analysis of the fetal brown fat tissue reveals that the myogenic pathway is predominantly upregulated in the fructose-treated group. Meanwhile, circulating fructose level is found to be significantly elevated in both fructose-fed dams and their fetuses. Importantly fructose gavage also acutely activates the myogenic program in mice brown fat. Together, our data suggest that maternal high-fructose intake impairs fetal brown fat development, resultantly attenuates diet-induced thermogenesis and causes metabolic disorders in adult offspring probably through inducing myogenic signature in brown fat at the fetal stage.

Hibernoma

Hibernomas are rare soft-tissue benign neoplasms composed of brown adipose tissue. In 1906, Merkel named these tumors Pseudolipoma, then in 1914, Grey coined the term as Hibernoma because of its similarity to brown fat in hibernating animal species. Symptoms secondary to extrinsic compression of neighboring structures may be present, although these tumors are uniformly benign. Hibernomas may be found anywhere in normal fetal brown fat but are most commonly located in the thigh. The etiology of Hibernomas is unknown. Molecular genetics show mutation in chromosome 11 which encodes the tumor suppressor gene MEN 1 [Multiple Endocrine Neoplasia type 1]. Among all benign lipomatous tumors approximately 1.6% accounts for Hibernomas.

Excessive Glucocorticoids During Pregnancy Impair Fetal Brown Fat Development and Predispose Offspring to Metabolic Dysfunctions.

Maternal stress during pregnancy exposes fetuses to hyperglucocorticoids, which increases the risk of metabolic dysfunctions in offspring. Despite being a key tissue for maintaining metabolic health, the impacts of maternal excessive glucocorticoids (GC) on fetal brown adipose tissue (BAT) development and its long-term thermogenesis and energy expenditure remain unexamined. For testing, pregnant mice were administered dexamethasone (DEX), a synthetic GC, in the last trimester of gestation, when BAT development is the most active. DEX offspring had glucose, insulin resistance, and adiposity and also displayed cold sensitivity following cold exposure. In BAT of DEX offspring, Ppargc1a expression was suppressed, together with reduced mitochondrial density, and the brown progenitor cells sorted from offspring BAT demonstrated attenuated brown adipogenic capacity. Increased DNA methylation in Ppargc1a promoter had a fetal origin; elevated DNA methylation was also detected in neonatal BAT and brown progenitors. Mechanistically, fetal GC exposure increased GC receptor/DNMT3b complex in binding to the Ppargc1a promoter, potentially driving its de novo DNA methylation and transcriptional silencing, which impaired fetal BAT development. In summary, maternal GC exposure during pregnancy increases DNA methylation in the Ppargc1a promoter, which epigenetically impairs BAT thermogenesis and energy expenditure, predisposing offspring to metabolic dysfunctions.

Hibernoma dorsal gigante. Presentación de caso

El Hibernoma o lipoma de grasa parda, es un tumor benigno extremadamente infrecuente. Presentamos el caso, de un paciente femenino de 12 años de edad con una tumoración gigante en región dorsal, de origen congénito, con una extensión desde la región cervical baja hasta el sacro, presentaba con ausencia de los músculos de la región glútea, se realizó estudios de imagen, así como química sanguínea, donde se evidencio anemia severa y desnutrición proteico energética, se organizó un equipo multidisciplinario centrado al tratamiento definitivo de la lesión, la cual provocaba además seria deformidad de la columna lumbar (cifoescoliosis), se logró la resección completa de la lesión, con un peso total de 12 Kg, con reconstrucción de los bordes anales sin afectar el esfínter anal, se mantuvo bajo seguimiento durante 1 años sin presentar ninguna recidiva de la lesión.

Hibernoma: a rare case of adipocytic tumor in head and neck.

BackgroundHibernoma is a rare soft tissue tumor stem from persistent fetal brown fat tissue. This benign tumor may occasionally occur in head and neck area and, in most cases, is characterized by an asymptomatic slow growth.Case presentationWe presented an uncommon case of hibernoma of the posterior cervical triangle occurring in a 30-year-old man referred to the department of otolaryngology. The patient suffered from a right, very painful, and rapidly growing mass since 3 months. MRI examination reported both an infiltrating mass and a homogenous enhancement of an underlying vascularization after the injection of intravenous contrast. According to the risk of sarcoma, a surgical procedure was made to completely excise the mass that was a hibernoma.ConclusionsHibernoma may occur with an uncommon clinical presentation imitating malignancy. MRI plays a key role in the differential diagnosis and surgery remains the better therapeutic approach.

308 Fetal brown fat deposition is increased by melatonin implants in sheep

308 Fetal brown fat deposition is increased by melatonin implants in sheep

Lipoma-like variant of hibernoma in anterior abdominal wall: A rare occurrence

Hibernoma is an uncommon benign tumor arising from the remnants of the fetal brown fat. We report a case of a 55 year old male with history of swelling over anterior abdominal wall on right side. Till 2009, 170 cases have been reported. As abdominal wall is rare site of its occurrence, we report this case.

Pediatric cervicomediastinal hibernoma: A case report

Hibernoma is a rare lipomatous tumor of brown fat origin. Though uniformly benign in nature these tumors may cause symptoms secondary to extrinsic compression of neighboring structures. Hibernomas may be found anywhere that normal fetal brown fat may be located but are most commonly located in the thigh. We present a case of a hibernoma presenting as an unusual cervicomediastinal mass in a 6-year-old male. This mass was discovered during a diagnostic chest x-ray for pneumonia and treated by resection. Complete surgical resection is considered curative. Hibernoma should be considered in the differential diagnosis of any lipomatous tumor.

Interscapular hibernoma—Case report and literature review

Hibernoma is a rare benign tumor that arises from the vestiges of fetal brown fat. We present a case of interscapular hibernoma. Computed tomography scan showed a well-circumscribed, hypodense mass with peripheral enhancement, and magnetic resonance imaging revealed intermediate high T1 and T2 signal intensities with incomplete fat suppression. Although it is rare, hibernoma should be included in the differential diagnosis of lipomatous soft-tissue tumors. This is a benign tumor with no malignant potential. Complete excision is the treatment choice.

Hibernoma—Case Report and Literature Review

Hibernoma is an uncommon benign fatty tumor that arises from the vestiges of fetal brown fat. We present a case report of a hibernoma of the back in a symptomatic 42-year-old man and describe the important clinical, histopathologic, and imaging findings. Computed tomography shows a well-defined hypodense mass with septations. Magnetic resonance imaging shows intermediate T1 and bright T2 signal of the mass and also demonstrates the characteristic marked contrast enhancement.

Axillary Hibernoma: MRI Characteristics: A Case Report

Hibernoma is a rare hypervascular benign soft tissue tumor arising from residual fetal brown fat. Awareness of the MR imaging appearances of this lesion may allow at least inclusion of hibernoma in the possible differential diagnosis prior to surgery.

Hibernoma: un extraño caso de masa cervical

The hibernoma is an uncommon benign tumor thought to arise from the vestiges of the fetal brown fat. The term hibernoma is derived from the microscopic similarity of this tumor to the glandular brown adipose tissue occurring in the organs of hibernation of certain animal species. There are reported about 100 hibernomas in the literature world wide and only a small number of them are in the neck. We report the case of a 33 years old male with a 20 months history of a painless mass in his right neck.

CCAAT/enhancer-binding proteins α and β in brown adipose tissue: evidence for a tissue-specific pattern of expression during development

CCAAT/enhancer-binding protein (C/EBP) alpha mRNA and its protein products C/EBP alpha and 30 kDa C/EBP alpha are expressed in rat brown-adipose tissue. Results also demonstrate the expression of C/EBP beta mRNA and its protein products C/EBP beta and liver inhibitory protein (LIP) in the tissue. The abundance of C/EBP alpha and C/EBP beta proteins in adult brown fat is similar to that found in adult liver. However, the expression of C/EBP alpha and C/EBP beta is specifically regulated in brown fat during development. C/EBP alpha, 30 kDa C/EBP alpha, C/EBP beta and LIP content is several-fold higher in fetal brown fat than in the adult tissue, or liver at any stage of development. Peak values are attained in late fetal life, in concurrence with the onset of transcription of the uncoupling protein (UCP) gene, the molecular marker of terminal brown-adipocyte differentiation. When adult rats are exposed to a cold environment, which is a physiological stimulus of brown-adipose tissue hyperplasia and UCP gene expression, a specific rise in C/EBP beta expression with respect to C/EBP alpha, 30 kDa C/EBP alpha and LIP is observed. Present data suggest that the C/EBP family of transcription factors has an important role in the development and terminal differentiation of brown-adipose tissue.

Mediastinal hibernoma, a rare tumor

Hibernoma is an uncommon soft tissue tumor that is derived from the remnants of fetal brown fat. Review of the world medical literature revealed 90 cases, 6 of which were intrathoracic. We present the seventh case of intrathoracic hibernoma; in this case, the hibernoma was within the mediastinum without direct invasion of other structures.

Iodothyronine 5'-deiodinase activity in rat brown adipose tissue during development.

Iodothyronine 5'-deiodinase activity in rat brown adipose tissue has a characteristic pattern of developmental changes that is completely different from that of the liver. Fetal brown fat exhibits an extremely high iodothyronine 5'-deiodinase activity that is approx. 10-fold that in adult rats. Even though brown fat iodothyronine 5'-deiodinase activity falls suddenly at birth, there is a new peak in the activity around days 5-7 of life, whereas it remains very low afterwards. Just after birth, brown adipose tissue iodothyronine 5'-deiodinase activity is already capable of stimulation by noradrenaline. The postnatal peak in brown fat iodothyronine 5'-deiodinase correlates with the known increase in the thermogenic activity of the tissue in the neonatal rat, thus reinforcing the suggestion that local 3',3,5-triiodothyronine generation could be an important event related to thermogenesis in brown adipose tissue. However, the high fetal activity was only slightly related to the thermogenic activity of brown fat. Moreover, the increased iodothyronine 5'-deiodinase activity of brown adipose tissue during fetal and neonatal life suggests a substantial contribution by brown fat in the overall extrathyroidal 3',3,5-triiodothyronine production in these physiological periods.

Immunocytochemistry of the Microtubules of fat-laden cells. Brown fat cells and adrenocortical cells in primary monolayer culture.

Cytoplasmic microtubules of fat-laden cells containing fine lipid droplets, such as brown fat cells and adrenocortical cells, were studied in relation to the metabolism of intracellular lipid. In these cells, the amount and distribution of lipid droplets reflect the state of inherent cellular function. Materials used were primary monolayer culture of fetal rat brown fat cells and that of bovine adrenocortical cells. The method was the immunocytochemistry with anti-tubulin antibody. When brown fat cells were being lipolyzed or the steroidogenesis of adrenocortical cells were being stimulated, the cytoplasmic microtubules in the cells were organized in a radial pattern in response to the behavior of the lipid droplets. It is assumed that the microtubules were in the regulation of cellular function in terms of the metabolism of lipid droplets in these cells. We have devised, in the course of the current study, a double fluorescence technique as an observational method whereby microtubules were observed immunocytochemically and lipid droplets by a secondary fluorescence with phosphine E staining.

Pyruvate dehydrogenase activity in liver and brown fat of the developing rat.

The total activity of pyruvate dehydrogenase (EC 1.2.4.1) and the fraction of the enzyme in the active form were assayed in brown fat and liver throughout the development of the rat. In brown adipose tissue, the total activity increased until the late suckling period. After weaning, a decrease was noted. The fraction of the enzyme in the active form did not increase until after 10 days of age, reached its highest level in the late suckling period and remained at this level after weaning. Pyruvate dehydrogenase in liver decreased in both total activity and percentage activity in the early neonatal period. Both parameters increased after this period, reaching their highest levels in the late suckling period. In both fetal liver and fetal brown fat, the total activity of pyruvate dehydrogenase was increased by in vitro incubation with insulin.

Growth and distribution of human fetal brown fat.

AbstractMacroscopic and microscopic examination of adipose tissue was carried out in a series of 20 human fetuses, ranging in weight from 380–3032 gm, in an attempt to identify all areas of brown (multilocular) fat development and growth. Brown fat distribution in the human fetus takes the form of a highcollared vest affording coverage to the cervical, thoracic and abdominal viscera. Much of this fat lies deep within the body immediately outside the pleural and peritoneal membranes. the remainder overlies or borders muscles of the shoulder girdle and neck as distinct brown fat deposits deep to the subcutaneous layer of white (unilocular) fat. All brown fat bodies contain unilocular cells but they occur in very small numbers in the brown fat bodies of the posterior cervical triangle, anterior mediastinum and perirenal and suprailiac regions. Brown fat bodies usually develop along the course of large blood vessels and several of them develop direct vascular connections with the liver and kidneys. The total weight of fetal brown fat increases at a rate directly proportional to that of the liver and kidneys up to 2134 gm body weight and to that of the liver beyond this weight.