Abstract
Background
Hibernomas are rare benign tumors of brown fat tissue origin. These tumors are generally found in locations where fetal fat persists (back, axilla, thorax and retroperitoneum).
Methods and Results
We report a case of a patient with an asymptomatic neck mass that initially presented for evaluation of hoarseness. Imaging and complete surgical excision of the mass were performed and revealed hibernoma. Review of the literature for the presentation of hibernoma in the neck is performed.
Conclusion
Hibernomas are rare benign tumors that infrequently present in the neck. Complete surgical removal is curative. To date no malignant transformation or metastasis has been described.
1
Introduction
Hibernoma is an uncommon benign tumor from the vestiges of brown adipose tissue. In the literature, approximately 100 cases have been reported and around 10 have been described in the head and neck region . It generally presents as a slowly growing, asymptomatic mass in the subcutaneous regions of back, thighs, thorax, or shoulder. A case is presented below where this tumor was diagnosed as an asymptomatic level IV neck mass.
2
Case report
A 46-year-old male with a smoking history was referred to the Department of Otolaryngology-Head & Neck Surgery of Tufts Medical Center for the evaluation of a 6-week history of intermittent hoarseness. A conservative trial of reflux therapy had failed to improve his symptoms. The patient did not report any dyspnea, dysphagia or odynophagia.
On physical examination, a subtle increased fullness was noted in level Va of the right neck. The overlying skin was normal and the region was nontender. The remainder of the neck exam was normal. Flexible fiberoptic laryngoscopy revealed the right true vocal fold to have an erythematous granular appearance with normal abduction and adduction.
A CT of the neck with contrast and demonstrated a round, well-defined, low-density mass measuring 4.5 × 3.0 cm in the right neck. The mass was noted to be superior to the right subclavian vein, anterior to the scalene muscles and lateral to the carotid space contents. No cervical lymphadenopathy or other well-defined aerodigestive masses were identified ( Fig. 1 ).
The patient underwent microlaryngoscopy with biopsy and removal of the neck mass. A broad based hemorrhagic mucosal lesion was noted on the right true vocal cord and was removed. Next, a horizontal lower neck incision was performed at the posterior aspect of the sternocleidomastoid. The mass was noted to be well-encapsulated and did not appear associated with the brachial plexus or carotid sheath contents. Careful dissection from surrounding tissue enabled complete removal and the operative field was closed in a routine fashion. The patient’s postoperative course was uneventful.
On pathology, the vocal fold lesion was consistent with a hemorrhagic cyst. The right neck mass measured 4.5 × 3 × 2 cm and was described as a tan–pink tumor that was encapsulated, soft to firm, and lobulated. Histopathologic diagnosis was consistent with hibernoma ( Fig. 2 ).
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