Hibernomas of the head and neck

Hibernoma in the clavicular fossa: A case report and literature review

A hibernoma is a benign soft tissue tumor consisting of brown adipose tissue. The tumors are mostly located in the thigh, back, and shoulder region. They are rarely found in the supraclavicular fossa. We report a 39-year-old woman who presented with a painless, slow-growing mass on the left supraclavicular fossa for nearly 15 years. Magnetic resonance imaging (MRI) showed an inhomogeneous round mass with a slightly hyperintense signal on fat-suppression T2-weighted imaging that compressed the adjacent tissues and subclavian vessels. Computed tomography angiography indicated a rich blood flow signal. Postoperative histology confirmed the diagnosis of a hibernating tumor. Although comprehensive imaging is important in the determination of tumor for the size, location, and nature, computed tomography angiography provides clear indication of the vascularity of the tumor, which provides vital clinicopathologic data for surgeons.

Hibernoma larynx with large multinodular goitre: unusual airway challenge

A 56-year-old man presented with a 6-month history of progressively increasing neck swelling, dysphagia and hoarseness of voice. CT scan revealed multi-nodular goitre and also showed a lesion in the supraglottis. It also showed another lesion in the supraglottis. Fine-needle aspiration cytology of thyroid revealed follicular cells. Routine flexible laryngoscopy was performed to evaluate vocal cord function; however, we found a smooth well-defined lesion just above the glottis, obstructing the direct view of the vocal cords, and an endangered airway. A provisional diagnosis of a laryngeal cyst was made. With all necessary precautions intubation was performed with a bougie and a reinforced endotracheal tube was inserted. Total thyroidectomy was performed first. With direct suspension laryngoscopy an attempt was made to deliver the laryngeal lesion, however, the lesion could not be removed. A suprahyoid lateral pharyngotomy was performed to deliver the lesion. Histopathology of the lesion revealed hibernoma.

Laryngeal hibernoma: case series of a rare tumor

BACKGROUND

Hibernomas are rare, benign tumors of brown adipose tissue uncommonly found in the head and neck.

METHODS

A review of the English-language literature was conducted for this study. We present a series of 2 laryngeal hibernomas treated with transoral laser microsurgical resection at a tertiary referral center over a period of 18 years.

RESULTS

Only 2 cases of laryngeal hibernoma have been previously described in the literature. Two additional cases were encountered at our institution. Preoperative imaging demonstrated a well-circumscribed neoplasm with fat density compatible with lipoma, but internal heterogeneity and vascularity seen in the context of liposarcoma. Transoral laser microsurgical resection was successfully performed in each case.

CONCLUSION

Despite unique radiographic features, hibernomas are difficult to distinguish from well-differentiated liposarcoma and lipoma variants without pathologic correlation. Complete surgical resection is indicated. In our experience, transoral laser microsurgical excision of laryngeal hibernomas is a safe, effective treatment modality with little associated morbidity.

A (9;11)(q34;q13) translocation in a hibernoma

The diagnosis of hibernoma has historically been made by histopathologic examination and finding of characteristic brown fat cells with granular multivacuolated cytoplasm. The diagnosis of hibernoma may be complicated, however, because seemingly diagnostic cells could be mistakenly identified as lipoblasts, leading to the erroneous diagnosis of well-differentiated liposarcoma. Cytogenetic alterations in lipomatous tumors are well established and could be used for diagnostic purposes. Previous cytogenetic abnormalities reported in hibernomas have included alteration of 11q13 region. Here, we present a case of a hibernoma with a novel cytogenetic alteration involving a reciprocal translocation between 9q and 11q that was useful in establishing the final diagnosis.

[Hibernoma: a rare case of cervical mass]

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.

Hibernoma of the neck

A hibernoma is a rare, benign, soft-tissue tumor composed of cells similar to those of brown adipose tissue. Only nine cases in the cervical area have been reported. Typically, hibernomas are asymptomatic and slow growing. Adequate treatment consists of complete excision. We describe an additional case of neck hibernoma and review the literature to clarify a pathologic condition rarely included in the differential diagnosis of cervical masses.

Fine-needle aspiration characteristics of hibernoma

BACKGROUND

Hibernoma is a rare, benign lipomatous tumor with features of brown fat. The preoperative diagnosis of hibernoma is difficult at times because its clinical, radiographic, and fine-needle aspiration (FNA) characteristics overlap with those of liposarcoma.

METHODS

The preoperative FNA findings of eight surgically excised hibernomas from seven patients (three men and four women, ages 24-60 years) were reviewed. The cytologic features were compared with the histologic features of the corresponding surgical specimens as well as lipomatous tumors and other lesions that may cause confusion in the differential diagnosis.

RESULTS

The FNA cytologic features of the hibernomas were found to correspond well with their histologic appearance. The FNA findings included small, round, brown fat-like cells with uniform, small cytoplasmic vacuoles and regular, small, round nuclei; delicate branching capillaries; and variable numbers of mature fat cells.

CONCLUSIONS

The FNA cytologic features of hibernoma are characteristic and useful in the preoperative investigation of lipomatous tumors, particularly with regard to excluding a diagnosis of liposarcoma.