Giant Lipoma: A Case Report

Abstract

A lipoma is a fatty tissue tumor presenting as a painless slowly growing mass that can affect any part of the body rich in adipose tissue. Lipomas can be present in the thigh, shoulder, trunk, etc, although they are usually small. We are reporting a 65-year-old man with a giant lipoma involving his left buttock and lumbar region.

Introduction

Alipoma is one of the most common benign mesenchymal tumors in the body and is composed of mature adipose cells. A lipoma can be found in almost all the organs¹ of the body where fat normally exists, which is why it is also known as an ubiquitous tumor or universal tumor.² While small superficial lipomas constitute simple surgical conditions, large and deep lipomas represent a real diagnostic and therapeutic challenge.³ Presentation is usually as a painless subcutaneous swelling. Other presentations depend on the site and size of the lesion and on local pressure effects.

Case Report

A 65-year-old male patient presented with complaints of swelling in the left gluteal region and a dull ache in left lower limb for the past three years. Examination revealed a large mass in the left gluteal region, extending to the left lumbar region, which was nontender, soft in consistency, noncompressible with well-defined margins (Figure 1). The swelling was not fixed to the skin or underlying structures.

Figure 1.

The large mass in the left gluteal region extending to the left lumbar region.

Fine needle aspiration cytology (FNAC) of the swelling revealed mature fat cells suggestive of a lipoma. An X-ray revealed a soft tissue swelling with normal bone. A magnetic resonance imaging (MRI) scan revealed a well-circumscribed soft tissue swelling with septations, raising the suspicion of malignant transformation. The MRI delineated the extent of the tumor and revealed its relation to the adjacent structures. Thus it helped in planning the incision and operation.

The patient was positioned in a right lateral decubitus position under general anesthesia with orotracheal intubation. After adequate preparation and draping, a lazy incision was made over the swelling, extending from the upper to the lower extent of the tumor. Careful dissection was carried out. A part of the tumor was found under the gluteal muscles. Important neurovascular structures including the sciatic nerve and gluteal vessels were identified and preserved. The tumor was dissected out and excised en masse. The tumor measured 32.5 x 21 cm (Figure 2) and weighed 3.2 kgs. The wound was closed in layers over a suction drain. A histopathological examination revealed features consistent with a lipoma with no evidence of any malignant transformation. The postoperative period was uneventful.

Figure 2.

The tumor excised en-mass measured 32.5 x 21 cm.

Discussion

A solitary lipoma is the most frequent soft tissue tumor, often appearing between 40 and 60 years of age.⁴ For a lipoma to be referred to as “giant,” it should be at least 10 cm in diameter or weigh a minimum of 1000 grams,^4,5 as was the case in our patient. Its volume is the source of a good many social life problems (keeping the lipoma discreet in clothing, difficulties in dressing) and causes multiple health problems such as pain, difficulties in sleep, compression of nerves or vital structures, infections, etc.⁵

Only rarely are children affected. Lipomas may be single or multiple. Multiple lipomas are more common in women, many are seen in a familial setting.⁵

Diagnosis is primarily clinical, but malignancy has to be ruled out. In addition to FNAC, MRI⁶ has been well established to aid in arriving at a diagnosis and planning for surgery. Features that suggest malignancy include old age, large size, presence of thick septa, presence of nodular and/or globular or nonadipose mass-like areas, and decreased percentage of fat composition.⁷ Many of these factors were present in our case.

Johnson et al suggested that any soft tissue tumor that is greater than 5 cm, should be considered malignant until proved otherwise.⁸ In our case, the size of the tumor was >5 cm, but histopathology revealed a benign lesion.

Surgical excision is the treatment of choice because these large tumors may undergo malignant transformation.³ Another option for treatment of these giant tumors is liposuction,⁹ which was not considered in our case both because the patient did not give the consent and because of the possibility of malignant transformation. In our case, the primary concerns of the patient were the discomfort and dragging pain and the apprehension of malignancy, which were relieved completely after surgery. The preoperative findings and histopathological features confirmed the diagnosis of benign giant lipoma. These tumors have a tendency for recurrence, and the patients should be kept under a regular follow-up.

Conclusion

The presentation of a long-standing giant lipoma may resemble a malignant lesion. Surgical excision is the treatment of choice to alleviate the symptoms and the apprehension of malignancy and provides tissue diagnosis.