Hibernomas are usually located in the interscapular region, but may also be encountered in the cervical, thigh or axillary areas. Intra thoracic, intramuscular, abdominal and retroperitoneal lesions have also been described, as well as exceptional locations such as the uterus, breast, popliteal area, cranium, pericardium [1] or mediastinum. Lesions may be multiple or bilateral, are painless, but may cause symptoms related to their mass effect [2] or to their secretory activity, as they are known to sometimes produce steroid hormones. They are usually described as slow growing (but fast growth is also possible) and firm or rubbery and are mostly encountered in adults in their thirties, and differential diagnosis with lipomas and liposarcomas must be taken into consideration, given that clinical presentations of the three pathological entities often overlap [3] [4]. Once the diagnosis of hibernoma is established, the physician does not need to be concerned about malignant transformation or metastasis [5]. However, recurrence is possible, although very rare.

• Asymptomatic

  It generally presents as a slowly growing, asymptomatic mass in the subcutaneous regions of back, thighs, thorax, or shoulder. [entokey.com]

  Hibernomas are rare, benign, and slow growing and are often asymptomatic incidental findings on imaging or physical exam [2, 3]. [hindawi.com]

  They are usually asymptomatic and have a slow growth pattern. Intrathoracic and pleural locations are exceptional for localization of hibernoma. [ncbi.nlm.nih.gov]

• Pathologist

  Pathologists should be aware of this variant of hibernoma to avoid misdiagnosis and excessive treatment. [ncbi.nlm.nih.gov]

  This richly illustrated and concise reference will be a practical and indispensible tool for general pathologists and pathologists in training, who are required to diagnose bone and soft tissue pathologies. [books.google.es]

  According to Furlong et al. (3), the lipoma-like variant is the most troublesome for surgical pathologists due to the presence of occasional multivacuolated adipocytic cells mimicking lipoblasts (3). [scielo.br]

  The pathologist examines the biopsy under a microscope. [dovemed.com]

• Falling

  Für den Fall einer sicheren marginalen Resektion bestehen diese Bedenken nicht, so dieses Vorgehen bei gegebener operativer Indikation zu empfehlen ist. [thieme-connect.com]

  You’re more likely to get encephalitis in the summer or fall when these insects are most active. Although the MMR (measles, mumps, rubella) vaccine has a long history of being safe and effective, in rare cases it has caused encephalitis. [healthline.com]

• Vomiting

  A 44-year-old patient was evaluated in the outpatient clinic: he reported abdominal pain for the last 5 months, associated with vomiting and sporadic sweating. Antihypertensive treatment was initiated, which provided a partial response. [elsevier.es]

  CT scan Angiomyolipoma NO Sansom [15] 1999 F 29 Lumbar pain + anorexia + vomiting CT scan NO NO Gülmez [16] 1999 F 28 Abdominal pain Intravenous urography NO NO Furlong [4] 2001 No data No data Abdominal pain No data NO NO Cantisani [17] 2003 M 38 Abdominal [sciencerepository.org]

  The manifestations of HSVE include low-grade pyrexia accompanied by severe headache, nausea, vomiting, and lethargy, followed by neurological features, which may include cognitive dysfunction (confusion, acute memory disturbances and disorientation), [orpha.net]

  This rapid increase in ammonia may lead to episodes of irritability, refusal to eat, and vomiting. In some affected individuals, signs and symptoms of arginase deficiency may be less severe, and may not appear until later in life. [ghr.nlm.nih.gov]

  Symptoms may include feeding problems, vomiting, poor growth, seizures, and stiff muscles with increased reflexes (spasticity ). [rarediseases.info.nih.gov]

• Nausea

  The manifestations of HSVE include low-grade pyrexia accompanied by severe headache, nausea, vomiting, and lethargy, followed by neurological features, which may include cognitive dysfunction (confusion, acute memory disturbances and disorientation), [orpha.net]

  […] or paralysis in certain areas of the face or body Muscle weakness Problems with speech or hearing Loss of consciousness In infants and young children, signs and symptoms might also include: Bulging in the soft spots (fontanels) of an infant's skull Nausea [mayoclinic.org]

  Nausea Fever. Seizures Drowsiness. If left untreated, the symptoms tend to progress, become increasingly worse, and can ultimately lead to death. Diagnosis of HSE The rapid onset and development of HSE presents a dilemma to the clinician. [encephalitis.info]

  Signs and symptoms Patients with HSE may have a prodrome of malaise, fever, headache, and nausea, followed by acute or subacute onset of an encephalopathy whose symptoms include lethargy, confusion, and delirium. [emedicine.medscape.com]

• Failure to Thrive

  Failure to thrive and dysmorphic features were also seen. Conclusion: Hyperargininemia commonly manifests as regression, failure to thrive, spasticity, seizures with or without microcephaly. [pediatricneurosciences.com]

• Subcutaneous Mass

  Figure 1: Enhanced CT demonstrated a subcutaneous well-defined mass of the right back. Its density was higher than subcutaneous fat. [healio.com]

  A 35 year old woman presented to our outpatient clinic with an 18 weeks history of a painless, gradually enlarging subcutaneous mass at mons pubis. Prior to presentation, she had no reported significant history. [ijpmonline.org]

  The patient reported a slow growth of this mass over several years. Physical examination revealed a palpable, soft, subcutaneous tumor in the left dorsal region, without apparent involvement of the superjacent skin, which was painless on palpation. [anaisdedermatologia.org.br]

  Computed tomography (CT) shows well-circumscribed mass with attenuation intermediate between subcutaneous fat and skeletal muscle. [dermnetnz.org]

• Skin Lesion

  See also[edit] Lipoma Skin lesion List of cutaneous conditions References[edit] ^ "On the ultrastructure of hibernoma". Cancer. November 1975. ^ Lexicon Orthopaedic Etymology. CRC Press. 1999. p. 147. ISBN 9789057025976. ^ a b c d Furlong, M. [en.wikipedia.org]

  "Benign skin lesions: lipomas, epidermal inclusion cysts, muscle and nerve biopsies". Surg Clin N Am. vol. 89. 2009. pp. 677-87. Bancroft, LW, Kransdorf, MJ, Peterson, JJ, O’Conner, MI. [dermatologyadvisor.com]

  “Benign skin lesions: lipomas, epidermal inclusion cysts, muscle and nerve biopsies”. Surg Clin N Am. vol. 89. 2009. pp. 677-87. (Review of lipoma and epidermal inclusion cysts including workup and treatment.) [endocrinologyadvisor.com]

• Skin Rash

  Other described symptoms include urinary incontinence and rarely skin rash. CSF usually shows lymphocytic pleocytosis but a normal CSF does not exclude the diagnosis and simply implies that there is no meningeal inflammation [3]. [raredisorders.imedpub.com]

• Irritability

  HSVE include low-grade pyrexia accompanied by severe headache, nausea, vomiting, and lethargy, followed by neurological features, which may include cognitive dysfunction (confusion, acute memory disturbances and disorientation), behavioral changes (irritability [orpha.net]

  This rapid increase in ammonia may lead to episodes of irritability, refusal to eat, and vomiting. In some affected individuals, signs and symptoms of arginase deficiency may be less severe, and may not appear until later in life. [ghr.nlm.nih.gov]

  Hyperammonemia can cause irritability, lethargy, refusal to eat, breathing difficulty, movement disorders, vomiting and, in severe cases, coma.[2] If arginase deficiency is undiagnosed or if the person with the disorder is unable to follow the strict [rarediseases.info.nih.gov]

• Paresthesia

  We report an illustrative case of a 27-year old female subject with a progressively increasing mass lesion causing brachial plexus compression, ipsilateral shoulder pain, C8 dermatomal paresthesia, and impairment of motor power. [neurologyindia.com]

  Meralgia paresthetica due to a thigh hibernoma: a rare diagnosis—case report European Orthopaedics Traumatology, 2013 Meralgia paresthetica (MP) is a symptom complex that includes numbness, paresthesias, and neuropathic pain in the anterolateral cutaneous [clinicajoelhoombro.com]

  […] expressing simian virus 40 (SV40) transforming genes prompted us to investigate the expression of p53 protein in these tumors.2,3 REPORT OF CASES Case 1 A 43-year-old white woman had a several-month history of an enlarging, right, infraclavicular mass with paresthesias [archivesofpathology.org]

  […] predilection of 4:1.1,2,11,15-20 Details on the presenting symptoms for the previous 4 spindle-cell hibernomas are absent, but most hibernomas present as asymptomatic, slow-growing, painless soft-tissue masses.1,5-7 A few hibernomas causing pain and paresthesia [healio.com]

The first step in diagnosing a hibernoma after the clinical suspicion is raised is to perform imaging procedures. A radiography of the affected region will show no bone erosion or calcification. Echography describes hyperechoic tissue, while Doppler imaging highlights the presence of enlarged vessels. Computer tomography scanning describes well vascularized, well circumscribed, heterogeneous, diffusely septated lesions with a possibly incomplete peripheral capsule. Hibernoma signal intensity in magnetic resonance imaging is variable [6], usually high, but slightly inferior to that of subcutaneous tissue [5]. The degree of homogeneity is variable [7]. This method shows diffuse gadolinium enhancement of an otherwise isointense or mildly hypointense tissue formation. Myxoid hibernomas, being richer in water have higher signal intensity on magnetic resonance imaging scans [8]. Fluorodeoxyglucose positron emission tomography shows important radiotracer capture [9] due to the fact that hibernomas contain numerous mitochondria and are metabolically very active. Scintigraphy also reveals high radiotracer uptake with 99mTc-tetrofosmin, 123I-meta-iodobenzylguanidine and 99mTc-methoxyisobutylisonitrile administration. If an angiography is considered to be necessary, it may reveal, besides intense vascularization, the presence of internal arterio-venous shunting [10] which is important information prior to excision.

If clinical and imaging differential diagnosis cannot exclude a malignancy, excision is imperative. Analysis of the surgical specimen reveals a light brown to gray mass of tissue surrounded by a thin capsule [11]. Microscopic examination reveals high -number of mature, multivacuolated or uni vacuolar adipocytes intersecting with brown fat, intense vascularization, and few adipocyte atypia. Tumors may, however, be more or less well differentiated. Immunohistochemical analysis shows a positive cluster of differentiation (CD) 68 and negative CD 34.

In cases where cytogenic analysis reveals the presence of a 11q13 translocation, liposarcoma is improbable [12]. Rearrangements in the 11q13-21 region can be detected using metaphase fluorescent in situ hybridization.

The literature provides only a few treatment details regarding this variant. [ncbi.nlm.nih.gov]

The treatment consisted of complete excision of the tumor. At a follow-up of 8 months, there was no recurrence. Keywords hibernoma, tumor, hand, treatment, surgery Introduction Hibernoma is a rare benign tumor of brown fat. [jotsrr.org]

Complete surgical excision is the treatment of choice, and is considered curative. Cite this Apa Standard Harvard Vancouver BIBTEX RIS Klevos, G., Jose, J., Pretell, J. A. A., & Conway, S. A. (2015). Hibernoma. [miami.pure.elsevier.com]

This review discusses the clinical features, radiologic and histopathologic characteristics, ancillary studies, suggested pathogenesis, differential diagnosis, and treatment of and prognosis for these uncommon lesions. [ncbi.nlm.nih.gov]

There are multivacuolated cells and a cell with a central nucleus IMMUNOHISTOCHEMISTRY Positive • S100 • Oil red O • Sudan black Negative • CD 34 • P53 PROGNOSIS BIOLOGICAL BEHAVIOR • Hibernoma is benign and does not metastasize or convert to a malignancy [tumorsurgery.org]

[…] to help differentiate from malignancy The radiological report should include a description of the following: form, location and size tumor margins and transition zone relations to the muscular fascia relation to neurovascular structures Treatment and prognosis [radiopaedia.org]

[…] typically prominent; cytoplasm multivacuolated, oval, eosinophilic, granular LM DDx reaction to silicone implant Gross lobulated lesion, light-brown, usually extremities Site soft tissue - adipocytic lesions Clinical history young adults Prevalence uncommon Prognosis [librepathology.org]

TERMINOLOGY Synonyms Fetal lipoma, lipoma of embryonic fat Definitions Benign tumor most frequently occurring in younger adults, with differentiation toward brown fat Tumor has characteristic cytogenetic aberrations, mainly involving 11q13-21 ETIOLOGY [basicmedicalkey.com]

He subsequently underwent dual time point FDG PET/CT imaging which revealed a significant rise in standard uptake value (SUV) within the lesion over time, favoring a malignant etiology. [ncbi.nlm.nih.gov]

Etiology The etiology involves clinically significant persistence of remnants of or accumulation of brown fat in regions where small amounts of brown fat normally persist as vestigial remnants. [dermatologyadvisor.com]

There are multiple etiologies for why a hibernoma would form in the eyelid. [e-ijd.org]

[…] brown fat Tumor has characteristic cytogenetic aberrations, mainly involving 11q13-21 ETIOLOGY/PATHOGENESIS Developmental Anomaly Etiology unknown Many occur at sites of normal brown fat in fetuses and newborns Genetic changes in some CLINICAL ISSUES Epidemiology [basicmedicalkey.com]

Usually asymptomatic.[3] Epidemiology: Young adults. Gross Well-circumscribed. Lobulated and light-brown on sectioning. [librepathology.org]

Epidemiology[edit] 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. [en.wikipedia.org]

Definition / general Lipoma containing prominent brown adipocytes that resembles normal brown fat as classic lipoma resembles white fat Epidemiology Rare (2% of lipomas) Mean age 26 - 38 years; 60% male Sites Most commonly in axilla, back, mediastinum [pathologyoutlines.com]

Neurology and Neurosurgery Czech and Slovak Ophthalmology Czech and Slovak Psychiatry Czech Geriatric Review Czech Gynaecology Czech Rheumatology Czech Dental Journal Czech Urology Czech-Slovak Dermatology Czecho-Slovak Pathology Czech-Slovak Pediatrics Epidemiology [prolekare.cz]

Pathophysiology Pathophysiology involves cytogenic abnormalities of chromosomes 11q13-21 and 10q22, which can cause a deletion in the MEN-1 gene. Structural rearrangements involving the long arm of chromosome 11 are characteristic. [dermatologyadvisor.com]

We describe the case of an intramuscular hibernoma and illustrate the pathophysiology of the observed hibernoma in relation to recent insights on physiological BAT. [ncbi.nlm.nih.gov]

These tumors are by definition benign entities but, given their propensity for growth over time, they require complete extirpation to prevent recurrence. [ncbi.nlm.nih.gov]

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2. Furlong M, Fanburg-Smith J, Miettinem M. The morphologic spectrum of hibernoma: a clinicopathologic study of 170 cases. Am J Surg Pathol. 2001;25(6):809–814.
3. Lee J, Gupta A, Saifuddin A, et al. Hibernoma: MRI features in eight consecutive cases. Clin Radiol. 2006;61(12):1029–1034.
4. Dursun M, Agayev A, Bakir B, et al. CT and MR characteristics of hibernoma: six cases. Clin Imaging. 2008;32(1):42–47.
5. Murphey M, Carroll J, Flemming D, et al. From the archives of the AFIP: benign musculoskeletal lipomatous lesions. Radiographics. 2004;24(5):1433-1466.
6. Cypess A, Lehman S, Williams G, et al. Identification and Importance of Brown Adipose Tissue in Adult Humans. N Engl J Med. 2009;360:1509–1517.
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8. Ritchie D, Aniq H, Davies A, et al. Hibernoma—correlation of histopathology and magnetic-resonance-imaging features in 10 cases. Skeletal Radiol. 2006;35(8):579-589.
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10. Angervall L, Nilsson L, Stener B. Microangiographic and histological studies in 2 cases of hibernoma. Cancer. 1964;17:685-692.
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12. Mrózek K, Karakousis C, Bloomfield C. Band 11q13 is nonrandomly rearranged in hibernomas. Gen Chrom Cancer. 1994;9(2):145-147.