A rare tumor in a rare localization: elbow hibernoma

¹Department of Orthopedic Surgery and Traumatology I, Mohammed V Military Teaching Hospital, Rabat, Morocco, ²Faculty of Medicine and Pharmacy, Mohammed V University, 10100, Rabat, Morocco

^&Corresponding author
Moustapha Etape, Department of Orthopedic Surgery and Traumatology I, Mohammed V Military Teaching Hospital, Rabat, Morocco

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Hibernomas are very rare benign tumors of brown adipose tissue. Their most frequent sites of occurrence include the thigh, shoulder, and back. We are reporting a rare case of elbow hibernoma in a 43-year-old woman with no comorbidity. She was referred to our hospital for a painless mass of the right elbow. On arrival, she reported that the mass appeared 15 years ago and its size has been increasing progressively with no history of body weight loss. Six years before the present consultation, she was operated on for mass removal by her attending physician. Her referral was motivated by the recurrence of the mass. Physical examination revealed a large mass located on the lateral aspect of the elbow with a large scar from a prior surgical operation. This was a non-pulsatile, soft, and painless spherical mass with a regular surface measuring 10cm x 7cm, mobile for both superficial and deep planes (A). Plain X-rays of the elbow revealed an extra-skeletal spherical mass (B). A magnetic resonance imaging revealed a well-defined extra-skeletal fatty mass in the lateral aspect of the elbow suggestive of liposarcoma (C). Following the imaging work-up, she was operated on for complete mass removal and biopsy. Her initial postoperative course was uncomplicated and so she was discharged on an oral analgesic to be reviewed in two weeks. The histopathological findings confirmed a lipoma-like hibernoma variant with no signs of malignancy (D). At the last follow-up of three years, the patient showed no mass recurrence.

Figure 1: A) a clinical image of the patient´s elbow showing the mass on the lateral aspect of the elbow; B) anteroposterior and lateral views of plain X-rays of the elbow, the yellow arrows on the image showing a well-defined extra-skeletal spherical mass; C) a magnetic resonance image of the elbow, the yellow arrow showing a well-defined extra-skeletal fatty mass; D) a histological section of the resected mass showing a microscopic feature of a lipoma-like hibernoma variant