|Year : 2013 | Volume
| Issue : 2 | Page : 168-170
Giant lipoma of the right gluteal region
Olakulehin Olawale Adebayo1, Babalola Oladimeji Ranti2, Akanbi Olusola Olateju1
1 Department of Surgery, Ladoke Akintola University of Technology Teaching Hospital, Oyo State, Nigeria
2 Department of Orthopaedics and Trauma, National Orthopaedic Hospital, Lagos, Nigeria
|Date of Web Publication||24-Dec-2013|
Babalola Oladimeji Ranti
Department of Orthopaedics and Trauma, National Orthopaedic Hospital, PMB 2009, Yaba, Lagos
Source of Support: None, Conflict of Interest: None
Lipomas are the most common benign mesenchymal tumors and can arise in any location where fat is found. They could present as a tiny swelling or as an enormous mass in a body region. When they are more than 10 cm in their widest dimension or greater than 1 kg in weight, they are called giant lipomas. Giant lipomas have been described in the thigh, shoulder and trunk. We present a case of a giant gluteal lipoma in a 62-year-old woman seen in our out-patient clinic.
Keywords: Giant, gluteal, lipoma
|How to cite this article:|
Adebayo OO, Ranti BO, Olateju AO. Giant lipoma of the right gluteal region. J Med Trop 2013;15:168-70
| Introduction|| |
Lipomas are benign tumors of mesenchymal origin containing mature adipocytes or fat cells. They are the most common benign mesenchymal tumors and can arise in any location where fat is found. Lipomas that are at least 10 cm wide or weigh a minimum of 1000 g are regarded as "giant" lipomas.  Lipomas are usually asymptomatic, but when they attain large sizes to be called giant lipomas, they may become symptomatic with the additional risk of malignant transformation.
Giant lipomas have been previously described in literature: Akinkunmi et al.  described a giant lipoma in the thigh of a female Nigerian; Silistreli et al.  described giant lipomas of the periscapular, cervical and abdominal areas. Our literature search however yielded no previously reported case of a giant gluteal lipoma. We present a case of a giant right gluteal lipoma in a 62-year-old woman seen in our out-patient clinic.
| Case Report|| |
Mrs. OY is a 62-year-old Yoruba woman who was first seen at the out-patient clinic at TOPA specialist Hospital, Osogbo, Osun State, Nigeria on account of an 8-year history of a slowly progressive and painless right gluteal swelling [Figure 1]. There was no swelling in any other part of the body. There was no preceding history of trauma, sudden rapid enlargement of the swelling or ulceration over the swelling. She had received no treatment prior to presentation. She presented on account of the increasing difficulty with lying on her right side and the cosmetic deformity.
Physical examination revealed a middle-aged woman with significant clinical findings only in the musculoskeletal system. There was a 24 cm × 15 cm × 10 cm near dumb-bell shaped mass in upper outer quadrant of the right buttock, non-tender, with a definite edge, not attached to the skin or underlying structures and was firm in consistency. The skin over the mass was grossly normal and the inguinal lymph nodes were not enlarged. There was no distal neurovascular deficit in the right lower limb and her chest was clinically clear.
Investigations requested for included the packed cell volume, which was 35%. Fasting blood sugar, electrolytes and urea and chest X-ray findings were within limits. A pelvic X-ray was not done pre-operatively. Patient was not forth-coming with finances and this made carrying out computer tomography (CT)/magnetic resonance imaging (MRI) and fine needle aspiration cytology difficult for her. Based on the clinical evaluation of the patient, an assessment of a giant right gluteal lipoma was made. Patient was worked up for surgery and had an excision biopsy of the mass done under spinal anesthesia.
Patient was positioned in the left lateral position under above anesthesia. An elliptical skin incision over the swelling was used to expose the mass. The mass was noted to be located in the subcutaneous tissue. Dissection between tissue planes was not difficult due to the well-formed pseudocapsule around the mass. A mass weighing 2.8 kg was excised with an overlying elliptical-shaped skin [Figure 2]. Wound was closed in layers with a drain left in the resultant cavity. Excised mass was sent for histology. The drain was removed after 48 h. The post-operative period was uneventful. She was discharged home 2 weeks after surgery to the out-patient clinic for follow-up. The review of the patient at the clinic at the 6 th month post-operation had no features suggestive of recurrence [Figure 3].
Details of the histology report was as follows: Macroscopic appearance; an irregularly shaped fluctuant greyish white tissue admixed in areas with fat and partly covered with negroid skin. It weighed 2.4 kg and measured 19.5 cm × 17.2 cm × 10.1 cm.
Microscopic appearance revealed sections showing skin tissue with atrophy covering a benign tumor. The tumor was essentially composed of mature adipocytes with dense fibrous tissue. There were cavities containing necrotic debris, cholesterol slits, macrophages and brownish yellow hemosiderin pigment.
| Discussion|| |
Lipomas are the most common benign mesenchymal tumors and can arise in any location where fat is found.  These tumors can occur at any age, but are most common in middle age, often appearing in people from 40 to 60 years old.  Giant lipomas are rare. However, when they do occur, common locations of such masses are in the trunk, thigh and shoulder.  Silistreli et al.  reported four cases of giant lipoma with weights in the range 1900-12,350 g. All were managed by open surgery with a follow-up period of 14 months; 5 years with no recurrence. Variants of lipoma include the hibernomas, angiomyolipoma and myelolipoma. 
Most lipomas tend to be asymptomatic. However giant lipomas, due to their size could be cosmetically disfiguring and exert pressure symptoms on nerves and vessels thereby causing functional impairment. A risk of recurrence following excision and of malignant transformation also exists with a giant lipoma.  Our patient found the mass cosmetically unacceptable and had difficulty lying on her right side.
A comprehensive clinical evaluation is vital to a diagnosis. However, definitive diagnosis can only be obtained by histology. Calcifications within the soft-tissue mass may also be evident on plain radiograph.  In a review of 35 cases of superficial lipomas using high-resolution real-time ultrasonography, it was observed that twenty-nine percent of the lipomas were hypoechoic, 22% were isoechoic, 29% were hyperechoic and 20% showed a mixed pattern to the surrounding fat tissue. An elongated isoechoic or echogenic mass in the subcutaneous tissues should suggest the diagnosis of a lipoma. 
Lipomas are seen on CT scan as well-delineated, homogeneous masses with negative attenuation coefficients ranging from –95 to –160. MRI usually provides more information because lipomas are uniformly bright on T1-weighted images and are dark on fat-suppressed sequences.  The presence of septa between adipocytes, which is further enhanced on contrast, suggests a malignant rather than a benign tumor.  Fine-needle aspiration cytology may also serve as an aid to pre-operative diagnosis and in differentiating between a lipoma and liposarcoma. However, this has been found to be unreliable as liposarcomas may contain areas of normal adipose tissue as a result of their lack of homogeneity. 
Open surgery is considered the treatment of choice for giant lipomas.  Patient was subsequently placed on follow-up visits as the risk of recurrence and/or malignant transformation cannot be completely ruled out. She was reviewed in our clinic at 6-months post-operation. No evidence of recurrence was noticed.
| Conclusion|| |
We present a rare gluteal giant lipoma, including clinical findings, gross and microscopic pathology managed by open surgical excision.
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[Figure 1], [Figure 2], [Figure 3]