Characterization of the myxoid variant of hibernoma

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.

Hibernomas: clinicopathological features, diagnosis, and treatment of 17 cases

Hibernomas are rare benign adipose tumors composed of brown fat cells with granular, multivacuolated cytoplasm admixed with white adipose tissue. They account for 1.6% of benign lipomatous tumors and approximately 1.1% of all adipocytic tumors. They are more common in the third and fourth decades of life. The most common location is the thigh, followed by the shoulder, back, and head and neck. Four histological types have been reported; abundant vascularity is characteristic, and atypias are rare. The treatment of choice for hibernomas is complete surgical excision. Metastases or malignant transformation have not been reported.This article presents a series of 17 patients with hibernomas diagnosed and treated at our institution from January 1986 to December 2009. Six men and 11 women (M:F, 1:2) had a mean age of 38 years (range, 10 months to 64 years). All patients underwent surgical treatment; 14 patients had marginal and 3 had wide excision. Adjuvants such as radiation therapy, chemotherapy, or embolization were not administered for any patient. The most common symptom was a painless palpable mass, followed by a tender or painful mass; in 2 patients, the tumor was an incidental finding. The duration of symptoms ranged from 1 month to 10 years (mean, 27 months). The most common location was the thigh, followed by the buttock, scapula, and neck. The most common histological variant was the typical variant followed by the lipoma-like variant. At a mean follow-up of 5 years (range, 1-9 years), local recurrences were not observed.

[Hibernoma of the thigh]

Hibernoma is a rare benign tumour of brown fat. It presents as a voluminous slow-growing mass in the regions where remnants of brown fat can remain in adults. We report a case of a hibernoma on the thigh and present the diagnostic and therapeutic elements of this type of tumour, whose differential diagnosis of liposarcoma.

Spindle-cell hibernoma: a clinicopathologic comparison of this new variant

Spindle-cell hibernoma is 1 of 4 histologic variants of hibernomas, which are rare lipomatous tumors distinguished from other lipomas by their brown fat component. This article presents a case of a spindle-cell hibernoma that developed in the groin of a 58-year-old man, and is 1 of only 5 known cases of spindle-cell hibernoma published in the scientific literature. Minimal information is available regarding the clinicopathologic characteristics of the 4 hibernoma variants: typical, lipoma-like, myxoid, and spindle-cell. Spindle-cell hibernoma is believed to be the rarest variant, accounting for approximately 2% of hibernomas. The spindle-cell variant predominantly develops in the fourth and fifth decades, with an average age at diagnosis of 42.5 years (range, 28-59 years). It has a male predilection of 4:1. Previously reported only in the posterior neck and scalp, the groin is now added to the sites of spindle-cell hibernoma occurrence. Our patient's tumor demonstrated low-attenuation on computed tomography and contained moderately-attenuating internal septae. Histologically, in addition to the multivacuolated brown fat component common to all hibernomas, spindle-cell hibernoma has a spindle-cell element without vacuolization that is CD34 positive. No prior treatment details are available on this particular variant. Our patient was treated by marginal excision and was disease free through 13 months of follow-up.