Giant Lipoma in an Identical Twin

Author:
Ashok Nimgade, MD, MPH, SM, and Ruthanne Lamborghini, DPT
McLean Hospital, Belmont, Massachusetts

Citation:
Nimgade A, Lamborghini R. Giant lipoma in an identical twin. Consultant. 2017;57(12):720-722.

A 66-year-old man presented for inpatient management of depression and bipolar disorder. At presentation, he was noted to have a large, painless, rubbery mass, with diameter of greater than 10 cm, medial to the left scapula (Figure 1). The mass had first been noted 6 years ago and had been diagnosed as a lipoma. The patient had thus far declined excision, citing an aversion to surgery.

Figure 1: A giant lipoma on the patient’s left thoracic trunk. Note the marked right-shoulder depression.

History. The patient noted having discomfort from the mass when he was supine. His history was notable for hyperlipidemia, acne, hypothyroidism, essential tremor, benign prostatic hypertrophy, gallstones, irritable bowel syndrome, osteoarthritis, Dupuytren contractures, sleep apnea, frozen shoulder, and bursitis. He had been on antidepressants since the 1970s. His psychiatric medication regimen included venlafaxine, quetiapine, doxazosin, lorazepam, trazodone, and lurasidone. Other medications included levothyroxine, primidone, pravastatin, dicyclomine, and dronabinol.

The patient denied smoking, alcohol use, and drug use. He had been physically active much of his life, doing lifting work in shipping. After having lost his job 17 years ago, his depression had worsened, eventually leading to disability.

The patient had an identical twin brother who shared much of his medical history, including depression, which, while milder, also had led to disability. The twins had lived together all of their lives, except for about 3 years apart in their 20s. Neither the patient’s twin nor any other family member had lipomas. For most of their adulthood, the patient had outweighed his twin by 5 kg. By approximately 5 years ago, however, the patient had gained 25 kg, with his weight peaking at 94.5 kg (body mass index [BMI], 30.7 kg/m²). He attributed this weight change to his antidepressant and bipolar medications (especially olanzapine). He had subsequently lost this weight following adjustment of his medication regimen. The twin, however, had remained stable with a BMI of 22 kg/m².

Physical examination. At presentation, the patient had a height of 175 cm and a weight of 72.6 kg (BMI, 23.6 kg/m²). He was pleasant but disheveled, with a flat affect. He also had scoliosis, abdominal obesity, slight gynecomastia, and marked right-shoulder depression, more than would be expected in a right-handed person. A large rubbery mass was noted medial to the left scapular border. Manually raising the lipoma seemed to allow deeper breaths. Therefore, we hypothesized that surgical removal of the mass might improve his body mechanics. To help test this hypothesis, we created a soft elastic harness to distribute the weight of the lipoma across his torso (Figure 2). We measured his range of motion before and after applying the harness (and then, later, after surgical excision of the lipoma).

Figure 2: A harness was fashioned for redistributing the weight of the giant lipoma. The patient’s abdominal obesity is readily apparent.

Diagnostic tests. The results of basic laboratory tests, including a complete blood cell count, a comprehensive metabolic panel, and urinalysis, were within normal limits. Because lipomas represent a lipid abnormality, a lipid panel was performed, the results of which were unremarkable, which may have been a result of his dyslipidemia regimen. Because of an association of lipomas with hypothyroidism, a thyrotropin test was ordered, the results of which also were unremarkable, given that he was on thyroid-hormone replacement therapy. Testosterone levels also were studied because of theoretical concerns about peripheral conversion of androgens to estrogens in fatty tissue, especially in light of the slight gynecomastia and lipoma. His total testosterone level was high at 839 ng/dL, but his free testosterone was within normal limits at 9.4 ng/dL.

Treatment. Two months after initial presentation, the patient underwent resection of a 1.75-kg lipoma. Upon reexamination 6 months postexcision, he noted improved self-image and sleep comfort. He appeared clean-shaven and was more expressive. His trunk bore a healed 13 cm surgical scar (Figure 3).

Figure 3: Six months after surgery, the patient stands to the right of his genetically identical (but thinner) twin brother. The 13-cm surgical scar was well-healed. Although his range of motion had markedly improved, the neck list and right shoulder depression persisted.

Outcome of the case. Postsurgically, his shoulder internal rotation had increased 100% bilaterally to the normal range of 80° to 90° bilaterally (the harness had predicted a 75% increase on the left and a 22% increase on the right). Shoulder retraction had increased 50% on the left and 20% on the right to the normal range of 60° to 70° bilaterally (the harness had predicted a 50% increase on the left and a 17% increase on the right). Neck extension had increased by 100% to 80° and flexion by 40% to 50° (the harness had predicted a 13% to 14% increase for both flexion and extension). Thus, while the harness had correctly predicted improvement in shoulder and neck motions, it did so much more accurately with the shoulders.

Discussion. Lipomas, with a prevalence of approximately 1%, are the most common benign soft-tissue mesenchymal tumors. Formed of adipose tissue, most are less than 1 cm in diameter and are typically mobile and nontender. Lipomas may develop virtually anywhere, and, if close to vital tissues, can mimic conditions ranging from neuropathies to angina to stroke.

Postexcision weights may underestimate the potential for harm given the low density of fat. Masses anchored deeper than 5 cm and tightly anchored to underlying structures deserve close investigation; in such cases, liposarcomas should be ruled out, given the potential for metastasis, through imaging studies (radiography and/or magnetic resonance imaging) and biopsy.¹

For several decades, investigators have suspected a genetic link involving lipomas,² but this has been demonstrated only for certain lipomas,¹ including familial multiple lipomatosis and Dercum disease, involving multiple painful lipomas. Genetic factors associated with lipomas include hypothyroidism and, possibly, fat metabolism. Hypothyroidism has been implicated in fat metabolism irregularities, which theoretically might predispose to lipomas. Our patient was hypothyroid; however, so was his twin, who was unaffected by lipoma. Modifiable risk factors include excessive alcohol consumption and, potentially, trauma,¹ both of which our patient denied.

Although obesity is not universally cited as a lipoma risk factor, the individuals in a series of large lipomas had a BMI of 30 kg/m² on average.¹ Defects in HMGA2 (involved in adipogenesis) have been found to be associated with obesity as well as lipoma formation in mice.³ Potentially, this case study of twins helps strengthen the case for obesity as a risk factor for solitary lipomas, given that the twins shared all of their genetic material and had lived more than 90% of their lives together. Of course, the potential for epigenetic changes, environmental variables, and other potential confounders remains, which may be elucidated in the future by way of other cases of twins discordant for large lipomas.

The patient attributed much of his weight gain to antidepressants, which he had been taking since the 1970s. The twins’ psychological differences diverged with time, with the patient needing substantially higher dosages of antidepressants and mood stabilizers over 4 decades, which in turn may account for his increased obesity. It is interesting to conjecture about the existence of a positive feedback cycle in which adiposity of the lipoma contributed to further inflammation and depression.

More systematic studies could be done on the use of harnesses, such as the one applied here, to assess altered body mechanics caused by large masses and the potential for postsurgical improvement. This assessment with a harness also might help overcome patients’ reluctance to undergo surgical excision. 

References:

1. Aust MC, Spies M, Kall S, Jokuszies A, Gohritz A, Vogt P. Posttraumatic lipoma: fact or fiction? Skinmed. 2007;6(6):266-270.
2. Wakeley C, Somerville P. Lipomas. Lancet. 1952;260(6743):995-999.
3. Arlotta P, Tai AK-F, Manfioletti G, Clifford C, Jay G, Ono SJ. Transgenic mice expressing a truncated form of the high mobility group I-C protein develop adiposity and an abnormally high prevalence of lipomas. J Biol Chem. 2000;​275(19):14394-14400.

Acknowledgement: The authors thank the study twins for their cooperation; Arkadiy Stolyar, MD, for introducing us to the patient; and Mariuccia Vittoria, MBBS, for manuscript suggestions and proofreading.