Hibernoma in the renal sinus: A case mimicking malignancy.

Introduction: Hibernomas are benign tumors of brown adipose tissue. Hibernoma in the renal sinus is extremely rare. Herein, we present the third known case of renal hibernoma. Case presentation: A 71-year-old man reported to our department with a left kidney tumor with an average growth rate of 5 mm/year and a progressive contrast effect on computed tomography. It was diagnosed as a hibernoma following a laparoscopic radical nephrectomy. Conclusion: We encountered a rare case of a hibernoma in the renal sinus. Development of new and accurate diagnostic methods for hibernoma, without resorting to nephrectomy, is essential.

A Rare Case of Large Lateral Chest Wall Hibernoma.

Hibernomas, rare benign tumors originating from brown adipose tissue, pose diagnostic challenges due to their infrequent occurrence and slow growth. We present a case of a 38-year-old woman with a progressively enlarging mass in her right lateral chest wall, initially stable in size but growing during pregnancy and causing pain and functional impairment. Radiological evaluation, including x-ray and MRI, provided inconclusive results, necessitating a biopsy for a definitive diagnosis. Ultrasound-guided needle aspiration biopsy revealed typical histopathological features consistent with hibernoma. A subsequent total surgical excision with negative margins was performed. The patient achieved complete recovery without recurrence during two years of follow-up. This case underscores the importance of considering hibernoma in the differential diagnosis of adipose tissue tumors, particularly in atypical clinical presentations. Moreover, it highlights the challenges in diagnosing and managing hibernomas and emphasizes the role of MRI and biopsy in achieving accurate diagnosis and optimal treatment outcomes. Continued reporting of such cases is crucial for increasing awareness and improving the management of this rare tumor.

Lipomatoses.

Lipomatoses are benign proliferation of adipose tissue. Lipomas (benign fat tumors) are the most common component of lipomatosis. They may be unique or multiple, encapsulated or not, subcutaneous or sometimes visceral. In some cases, they form large areas of non-encapsulated fat hypertrophy, with a variable degree of fibrosis. They can develop despite the absence of obesity. They may be familial or acquired. At difference with lipodystrophy syndromes, they are not associated with lipoatrophy areas, except in some rare cases such as type 2 familial partial lipodystrophy syndromes (FPLD2). Their metabolic impact is variable in part depending on associated obesity. They may have functional or aesthetic consequences. Lipomatosis may be isolated, be part of a syndrome, or may be visceral. Isolated lipomatoses include multiple symmetrical lipomatosis (Madelung disease or Launois-Bensaude syndrome), familial multiple lipomatosis, the painful Dercum's disease also called Adiposis Dolorosa or Ander syndrome, mesosomatic lipomatosis also called Roch-Leri lipomatosis, familial angiolipomatosis, lipedema and hibernomas. Syndromic lipomatoses include PIK3CA-related disorders, Cowden/PTEN hamartomas-tumor syndrome, some lipodystrophy syndromes, and mitochondrial diseases, especially MERRF, multiple endocrine neoplasia type 1, neurofibromatosis type 1, Wilson disease, Pai or Haberland syndromes. Finally, visceral lipomatoses have been reported in numerous organs and sites: pancreatic, adrenal, abdominal, epidural, mediastinal, epicardial… The aim of this review is to present the main types of lipomatosis and their physiopathological component, when it is known.

A Rare Coexistence of Hybrid Tumor Low-grade Fibromyxoid Sarcoma/Sclerosing Epithelioid Fibrosarcoma and Hibernoma in the Same Thigh: A Case Report.

Introduction: We encountered a unique case of a patient with two distinct tumors coexisting in the same thigh. To the best of our knowledge, this combination of tumors in the same anatomical region has not been previously described in the literature. Case Report: This case report describes a 38-year-old Caucasian male with a painless mass in his right thigh, which was later diagnosed as a hybrid tumor composed of low-grade fibromyxoid sarcoma and sclerosing epithelioid fibrosarcoma, as well as a second tumor, which was diagnosed as a hibernoma. The patient underwent neoadjuvant chemotherapy and surgical excision, followed by adjuvant radiotherapy and treatment for metastatic recurrence. Conclusion: The rarity of this case highlights the need for interdisciplinary collaboration and further investigations into the behavior and management of hybrid tumors. This case also underscores the importance of an accurate histological diagnosis aided by immunohistochemistry and molecular analyses.

Spindle Cell Hibernoma of Perinephric Adipose Tissue: A Case Report.

Hibernoma is a relatively uncommon benign neoplasm of brown adipose tissue which usually affects head and neck region, thigh and rarely breast. There are different subtypes of hibernoma with the spindle cell-type is the least common one. Herein, we are reporting a case of this rare spindle cell hibernoma in a location which has not been previously reported: perinephric adipose tissue. This tumor was presented as a renal mass on imaging.

Hibernoma: a case report of a rare cardiac tumour.

Background: A cardiac hibernoma is a rare phenomenon, with just a handful of reports in the literature. They are difficult to characterize with conventional imaging including echocardiography, computed tomography (CT), cardiac magnetic resonance (CMR), or positron emission tomography (PET). Their definitive diagnosis relies primarily on histopathology via either endovascular or surgical biopsy. Previous case reports have entailed surgical excision followed by histopathology; however, surgery may be unfavourable in some patients with increased perioperative risk. Case summary: We present the case of a 57-year-old woman who was referred to our cardiology service with an interatrial lipomatous mass found incidentally on chest CT for assessment of rib fractures. She had 6 months of unexplained syncope, which was attributed to superior vena cava (SVC) compression demonstrated by chest CT. The mass had benign characteristics on echocardiography, CT, and CMR but was glucose-avid on PET, which indicated a possible malignancy such as liposarcoma. Her comorbid and very significant airways disease precluded her from surgical excision, so instead, endovascular biopsy was performed. Histopathology showed brown fat which was negative for mouse double minute 2 amplification on fluorescence in situ hybridisation testing; hence, a diagnosis was made of hibernoma, a rare benign tumour of brown fat. Given the benign diagnosis and her surgical risk with severe chronic obstructive pulmonary disease, a multidisciplinary recommendation was made favouring conservative management, with careful ongoing follow-up and the consideration of SVC stenting if symptoms progressed. Discussion: The definitive diagnosis of a cardiac hibernoma is complex and relies heavily on histopathology due to the contradictory findings on chest imaging. Careful consideration of management within a multidisciplinary team setting is essential to achieve a successful outcome.

Lipoma-like hibernoma of the breast: A case report and literature review.

Hibernomas are uncommon and benign tumors made up of brown fat cells. These tumors are typically found in the thigh, axillae, shoulder, back, neck, thorax, arm, and retroperitoneum. There are 4 histological variants of hibernomas, including the typical pattern, myxoid, lipoma-like, and spindle cell variant. The lipoma-like variant is characterized by numerous univacuolated adipocytic cells with intermingled multivacuolated granular cells. It is worth noting that lipoma-like hibernoma in the breast is infrequent. In this case, we present a 72-year-old woman with a history of moderately differentiated cholangiocarcinoma, obesity, and no family history of breast cancer. She consulted for a mass sensation in her right breast that had been present for a year. The mass was not painful and showed no inflammation or nipple discharge. Upon physical examination, a palpable 14 cm mass was identified, occupying the 2 internal quadrants and causing deformation of the surface of the right breast. Imaging studies indicated a solid mass in the lower-inner quadrant of the right breast, which was oval-shaped, well-defined, and displayed internal vascularization. Initially, a diagnosis of low-grade liposarcoma was considered, leading to a core needle biopsy guided by ultrasound. However, the histopathology study revealed a lipoma-like hibernoma, an exceedingly rare benign lesion. Lipoma-like hibernoma can present as a palpable mass or may be incidentally discovered. It should be considered in the differential diagnosis of any lesion containing fatty content. Imaging methods may suggest its presence, but histopathology confirms the diagnosis and its accuracy prevents needless overtreatment.

Hibernomas: a rare benign lipoma subtype.

Hibernoma is a benign soft tissue tumor; it is extremely low in incidence, slow-growing and painless and is often mistaken for lipoma or liposarcoma. Diagnosis requires imaging and pathological analysis. Complete resection is the treatment of choice. We analyzed a case of lipoma from imaging and pathology perspectives and reviewed the relevant literature.

Intraosseous Hibernoma: A Rare Entity in Orthopedics With Peculiar Radiological Features.

Intraosseous hibernoma is a rare benign bone tumor derived from brown fat. It is typically found in the axial skeleton and is more commonly observed in women. It can manifest as a painful lesion or may be incidentally discovered. Intraosseous hibernoma often presents as a sclerotic lesion, although it can also manifest as a lytic lesion. Due to its varied radiographic appearance, it should be considered in the differential diagnosis of bone lesions as it can mimic metastatic lesions as well as other sclerotic and lytic bone lesions. Therefore, obtaining a biopsy of the lesion is crucial for an accurate diagnosis. In this report, we present the clinical, radiological, and histopathological findings of two cases of intraosseous hibernoma and provide a concise overview based on a review of the literature.

Breast hibernoma in a male patient: a rare case report and review of the literature.

Hibernomas are uncommon, benign, lipomatous tumours of brown fat. Although hibernomas may arise from any region where brown fat exists, common locations include thigh, shoulder, back and neck. We report a rare finding of a breast hibernoma in a 43-year-old male. The patient was managed surgically with an excision of the breast mass. This report will outline the pathology and clinical findings of breast hibernomas and review of the literature.

Rare Cases of Hibernomas Associated With Bilateral Pheochromocytoma: A Report of Two Cases.

Hibernoma is an infrequent benign lipomatous tumor that shows differentiation to brown fat. It is a slowly growing tumor of variable consistency but often firmer than a classic lipoma, mobile, and rarely infiltrating. To date, there are only a few cases of adrenal hibernoma in the literature. Herein, we report two cases. The first one is that of a 24-year-old female presenting with a bilateral adrenal incidentaloma discovered in the setting of abdominal pain whose histological study individualized a bilateral pheochromocytoma associated with a hibernoma. The second case is that of a young male of 23 years old. He was operated on in adolescence (age 14) for a left pheochromocytoma. The outcome was marked by the recurrence of the Menards triad ("headache, palpitations, and sweating") and hypertension at the age of 23 years. It was due to the appearance of a contralateral right pheochromocytoma, whose histological study showed an association with a hibernoma, and the genetic study revealed Von Hippel-Lindau (VHL) disease.

Oral hibernoma along with multiple lipomas.

'Hibernoma' is a neoplasm that arises from vestiges of fetal brown fat, and its occurrence in oral cavity is extremely rare. Its most common locations include thighs, the inter-scapular region, and the cervical region. In the present case, a 37-year-old male patient reported to our department with a localized swelling on his lower left labial mucosa along with multiple cutaneous well-defined swellings on his right arm and abdominal region. Incisional biopsy was carried out. Histopathological examination revealed sheets of multi-vacuolated eosinophilic cells with the granular cytoplasm interspersed with fat cells suggestive of oral hibernoma. These are rare lesions and could be often a missed-out diagnosis. Therefore, it is imperative to consider oral hibernoma among the commonly considered differential diagnosis of oral mucosal swellings.

Intraosseous hibernoma: clinicopathologic and imaging analysis of 18 cases.

AIMS: Intraosseous hibernomas are rarely reported tumours with brown adipocytic differentiation of unknown aetiology, with only 38 cases documented in the literature. We sought to further characterise the clinicopathologic, imaging and molecular features of these tumours. METHODS AND RESULT: Eighteen cases were identified occurring in eight females and 10 males (median age = 65 years, range = 7-75). Imaging indication was cancer surveillance/staging in 11 patients and clinical concern for a metastasis was raised in 13 patients. The innominate bone (7), sacrum (5), mobile spine (4), humerus (1) and femur (1) were involved. Median tumour size was 1.5 cm (range = 0.8-3.8). Tumours were sclerotic (11), mixed sclerotic and lytic (4) or occult (1). Microscopically, tumours were composed of large polygonal cells with distinct cell membranes, finely vacuolated cytoplasm, central or paracentral small bland nuclei with prominent scalloping. Growth around trabecular bone was observed. Tumour cells were immunoreactive for S100 protein (15/15) and adipophilin (5/5), while negative for keratin AE1/AE3(/PCK26) (0/14) and brachyury (0/2). Chromosomal microarray analysis, performed on four cases, did not show clinically significant copy number variation across the genome or on 11q, the site of AIP and MEN1. CONCLUSION: Analysis of 18 cases of intraosseous hibernoma, to our knowledge, the largest series to date, revealed that these tumours are most often detected in the spine and pelvis of older adults. Tumours were generally small, sclerotic and frequently found incidentally and can raise concern for metastasis. Whether or not these tumours are related to soft tissue hibernomas is uncertain.

Intraosseous hibernoma in the rib.

A 64-year-old man was admitted with paroxysmal left-side thoracic pain. CT scan showed an irregular appearance, expansile, osteolytic lesion of the left seventh rib. Wide en bloc excision of the tumour was performed. Macroscopic examination showed that a 3.5 cm × 3.0 cm × 3.0 cm solid lesion with destruction of bone. Histological examination showed that the tumour cells were arranged in plate shaped and interspersed between the bone trabeculae. Mature adipocytes were noted in the tumour tissues. The immunohistochemical stainings showed that the vacuolated cells were positive for S-100 protein and negative for CD68 and CD34. These clinicopathological features were consistent with intraosseous hibernoma.

Retroperitoneal hibernoma resected via laparoscopic surgery.

Hibernomas are extremely rare, benign tumors of brown fat origin with no specific symptoms. Surgery is the only treatment option, and because a definitive preoperative diagnosis is often not obtained, open surgery is usually chosen. In this case, we performed laparoscopic surgery on a 33-year-old woman with retroperitoneal hibernoma. As in most cases, a definitive diagnosis had not been preoperatively made; therefore, we laparoscopically removed the retroperitoneal tumor of unknown pathology as a diagnostic treatment. We chose laparoscopic surgery because of the magnifying effect of the laparoscope and to minimize scarring. The surgery was uneventful, with a procedure time of 280 minutes and a blood loss of 20 mL. The postoperative course was uneventful with no complications or recurrence. We conclude that laparoscopic surgery may be a viable option for hibernomas.

The lipoma-like hibernoma: A case report of a rare entity.

Hibernoma is a rare tumor developing from fat cells. It is a slowly evolving, benign tumor that is rarely pain-inducing. The most frequently encountered histological form is the typical hibernoma. The main differential diagnosis is liposarcoma. Here we present a case of a lipoma-like tumor of the arm: a rare variant of hibernoma. A 45-year-old man presents with a swelling of the left arm evolving for one year. Physical examination revealed a mobile, firm, and well-defined mass of the lateral left upper arm measuring 5 cm in length with no cutaneous lesions overlying. MRI and ultrasound confirmed the presence of a highly vascularized mass suggestive of a liposarcoma. A biopsy of the mass was performed concluding to a lipoma with no evident signs of malignancy. The patient underwent a surgical resection of the mass. Histopathological examination showed a well-differentiated adipose proliferation arranged in diffuse patterns of mature adipocytes. Large hibernoma-like foci were also noted. The diagnosis of a lipoma-like hibernoma was confirmed. Hibernoma represents is an uncommon benign tumor. It usually occurs in areas where the brown fat persists, including the thighs, shoulders, back, and neck in decreasing frequency. Commonly, this tumor occurs between the second and third decades of life. Clinically, it presents as a slow growing, painless mass. It may occasionally be painful due to compression of the surrounding structures. MRI shows T1w and T2w hyperintensity, with contrast enhancement after gadolinium injection. On histopathological examination, the structure is distinguished by an association of mature cells, round cells with central nuclei and eosinophilic cytoplasm, and multivacuolated cells. Surgical excision is the optimal treatment. The differential diagnosis concerns lipomas and well-differentiated liposarcomas. Lipoma-like hibernoma is an uncommon benign tumor which might imitate a liposarcoma clinically and radiologically. Histopathological examination is necessary to establish the diagnosis.

Hibernoma, tumor benigno infrecuente / Hibernoma, rare benign tumor

El hibernoma es un tumor limítrofe, benigno de comportamiento agresivo, de tejidos blandos, raro en frecuencia, que se origina a partir de los adipocitos pardos residuales, afectando principalmente a mujeres entre 10 a 20 años. Clínicamente se presenta como tumoración, más frecuente en los muslos, de crecimiento lento, móvil, firme e indolora. En los estudios de imagen, puede resultar difícil realizar un diagnóstico diferencial por su similitud con neoplasias malignas. El tratamiento ideal es la resección quirúrgica con márgenes amplios para evitar cualquier tipo de recurrencia local. Se presenta el caso de un hibernoma típico, manejo y tratamiento quirúrgico realizado.

Hibernoma is a borderline tumor, benign with aggressive behavior, of soft tissues, rare in frequency, which originates from residual brown adipocytes, mainly affecting women between 10 and 20 years of age. Clinically it presents as a slow-growing, mobile, firm and painless tumor, more frequent on the thighs. In imaging studies, it can be difficult to make a differential diagnosis due to its similarity to malignant neoplasms. The ideal treatment is surgical resection with wide margins to avoid any type of local recurrence. The case of a typical hibernoma, management and surgical treatment performed is presented.

Diagnosis of Intraosseous Hibernoma of an Appendicular Skeleton in an Adult - A Rare Case Report.

Introduction: Hibernoma is an uncommon benign tumor composed of multivacuolated brown adipocytes described in the literature a decade back. Intraosseous hibernomas are extremely rare with propensity to affect axial skeleton. Involvement of appendicular skeleton has been reported only twice in the literature till date. Case Report: We present a case of solitary, painless mass in the left proximal tibia mimicking neoplasm in a 35-year-old male. The plain radiographs revealed a lytic lesion with well-defined margin at the junction of metaphyseal-diaphyseal region of the left proximal tibia. The lesion was hyperintense on T2 and hypointense on T1 with heterogenous enhancement on contrast imaging. FDG-PET showed high uptake of fluorodeoxyglucose. Histopathological examination revealed the presence of multivacuolated cytoplasm with abundant mitochondria suggestive of hibernoma. On immunohistochemistry, the cells were positive for S-100. Conclusion: The findings of imaging modalities are non-specific and histopathological examination is required to confirm the diagnosis of hibernoma. Intraosseous hibernoma needs to be considered as a differential diagnosis of sclerotic bone lesion. Further, evaluation with regular follow-up with imaging will be required if the mass undergoes any clinical changes. Both radiologists and pathologists, need to be aware of this rare entity to avoid misdiagnosis of the uncommon lesion.

A Case Report of Axillary Hibernoma: US, CT, MR, and Histopathologic Findings.

Hibernoma is a rare benign tumor of brown adipose tissue. Herein, we report a case of axillary hibernoma in a 53-year-old female and discuss the various radiologic findings. The US revealed a 4.5-cm well-defined oval heterogenous hyperechoic mass in the right axilla with anterior displacement of the axillary vessels. Non-enhanced chest CT showed a 5.0-cm well defined, oval, and low-attenuated mass. MRI demonstrated a 5.5-cm mass with heterogeneous intermediate-to-high signal intensity on T1-and T2-weighted images and irregular enhancement at the peripheral portion. The patient underwent an US-guided core needle biopsy and the final diagnosis was hibernoma.