Massive Localized Lymphedema in the Morbidly Obese Patient: A Clinical Entity Mimicking Lymphosarcoma

Massive localized lymphedema (MLL) is a benign soft tissue lesion that usually presents as a large mass in morbidly obese adults. Farshid and Weiss¹ first described MLL as an enlarging lesion in the obese population due to chronic lymph obstruction.¹ In a review of this rare pathology, Brewer and Singh² noted it is most commonly located in the lower extremities, followed by the anterior abdominal wall.² Even though the etiology of MLL is still unknown, the comorbidity common to all reported cases is obesity.³ Morbid obesity is thought to cause MLL by promoting either localized lymphatic obstruction or localized ischemia because of traction.^4,5,6 This rare lesion often mimics various morphological entities including malignancies, leading to possible misdiagnosis. However, with the prevalence of morbid obesity being on the rise,⁷ it is highly likely this pathology will be encountered more frequently in the future and will no longer be considered as rare. It is therefore important to be aware of this puzzling entity to avoid the misdiagnosis of a soft tissue malignancy. The objective of this article is to report a case of a rapidly growing MLL of the anterior abdominal wall, highlighting its clinical and pathologic features.

A 61-year-old, morbidly obese female (BMI = 42 kg/m²) presented with an adipose tissue mass of the right lower abdominal wall. She had a history of hysterectomy for uterine fibroids through a Pfannenstiel incision. The operation was complicated by occult small bowel injury, due to which she underwent a relaparotomy and resection of the injured small bowel loop, through a midline infraumbilical incision. After the second operation, she started developing a massive edema of the right lower abdominal wall, lateral to the midline incision. A computed tomography (CT) scan of the patient’s abdomen confirmed the absence of incisional hernia or sepsis of the abdominal wall. She refused further surgical intervention and was only treated conservatively with antibiotics and diuretics. However, the mass continued to grow and significantly affected her daily activities. Eventually, 5 years after the initial operation, the patient was referred to the authors’ department for resection of the mass along with apronectomy of the left lateral abdominal wall (Figure 1). Due to its poor blood supply and the inflammatory appearance of the surrounding skin, preservation of the umbilicus was not feasible. The operative specimen weighed 13.5 kg and consisted of 4 sizable adipose tissue areas measuring from 12 cm x 6 cm to 45 cm x 12 cm. The overlying skin showed contractures, accentuated skin folds and, in some locations, had a peau d’orange appearance. On sectioning, the adipose tissue was edematous and showed whitish areas. Microscopy showed strap areas of fibrotic adipose tissue, focal hyalinization and the presence of subtle calcifications. Sections from the skin showed mild chronic cellular perivascular inflammatory infiltration, thickened dermis, and the presence of dilated lymphatic channels in some areas (Figures 2 and 3). The postoperative period was uneventful. The patient recovered well and was discharged on the third postoperative day (Figure 4). At a 6-month follow-up after the surgery, she was well with no signs of recurrence.

Massive localized lymphedema is a unique presentation of lymphedema resulting in a large, benign, painless mass that develops in morbidly obese patients. It is most commonly located on the medial thigh; however, it can also develop on the posterior and anterior thigh, lower leg, suprapubic region, upper arm, popliteal fossa, scrotum, penis, groin, and vulva.⁸ Due to their large size and the rarity of this distinct entity, many MLL cases every year are misdiagnosed as chronic lymphedema or benign soft-tissue tumors. MLL is associated with obesity even though the exact mechanism causing it is still unknown. Therefore, even though it is a rare condition, MLL prevalence is likely to increase in the future alongside the increase in prevalence of morbid obesity. The pathogenesis of MLL is not clearly understood, but it is generally thought to be caused by disrupted lymphatic flow and drainage due to fat accumulation in morbidly obese individuals.⁹ Another potential mechanism is that tension from the excessive weight causes localized ischemia on the affected adipose tissue, which subsequently triggers a cascade of biochemical events leading to fibrosis and accentuated fat lobules.^2,10,11 To reach a diagnosis, clinical and pathologic features should be taken into consideration.¹²

Clinically, MLL presents as a large painless mass that slowly enlarges over many years. The overlying skin often exhibits induration and a peau d’orange appearance, consistent with chronic lymphedema, and the subcutaneous fat is greatly expanded. Occasionally, as in the described case, there is a history of trauma or cellulitis in the affected area.¹³ On sectioning, the adipose tissue is edematous and punctuated by thickening and edematous fibrous septa. Histopathologically, it is characterized by dilated lymphatic channels with fibrotic and edematous tissue, without evidence of malignancy. Additionally, striking dermal fibrosis, expansion of fibrous septa between fat lobules with increased numbers of stromal fibroblasts, lymphatic proliferation and lymhangiectasia, multinucleated fibroblastic cells, and marked vascular proliferation are usually present.^14,15 Because of its myxedematous characteristics, MLL is often misdiagnosed as benign fibroma or well-differentiated liposarcoma, earning the name “pseudosarcoma.” Notably, if left untreated, MLL can progress to angiosarcoma, a malignant sarcoma that has been observed in 13% of cases reported in literature.¹⁰ Most patients tend to seek medical attention only when the mass reaches such a size as to interfere with gait and other daily activities.^16,17 It is important to state that the diagnosis of MLL is primarily clinical. Preoperative biopsy is not mandatory and,when performed, it is rarely diagnostic. Imaging diagnostic studies, such as CT scans or magnetic resonance imaging, are usually difficult to obtain because of the patient’s size and weight. When performed, their primary role is to rule out malignancy rather than to confirm the diagnosis of MLL.^5,18 In the described case, CT was also necessary to exclude incisional hernia. Since the underlying pathology is lymphedema, the initial treatment of MLL is complete decongestive physiotherapy.⁵ However, as in this patient’s case, due to the size of the MLL collection and its awkward location, it is extremely difficult for the patient to effectively incorporate those massive edematous areas into the lymphedema bandages. As they see no or little result, they usually discontinue any conservative measure, leaving surgical removal as their only potential treatment. Surgical resection, although technically difficult, is usually the preferred approach. After excision, recurrence is frequent, especially when conscientious adherence to compression and weight management do not continue. In morbidly obese patients, it is advisable for the patient to undergo weight reduction surgery prior to the removal of the MLL. A significant weight reduction will facilitate the excision of the MLL and potentially reduce the chance of recurrence.¹³

Massive localized lympedema is a rare entity that is likely to increase in frequency in the future as an emerging complication of the obesity epidemic.¹⁹ The diagnosis of MLL is challenging due to its rarity and the unusual microscopic features of the lesions.²⁰ Awareness of this entity, clinical correlation, and gross pathological correlation are critical in the separation of this distinctive entity from various conditions with similar clinical features.^1,18 The main reason for seeking treatment is mobility limitation due to the size of the lesion.²¹ The initial management of MLL is conservative, involving complete decongestive physiotherapy and weight reduction. However, due to poor results, patients usually discontinue their treatment, leaving surgical removal as their only potential treatment. After excision, recurrence is frequent.

Affiliations: Aristotle University of Thessaloniki, Thessaloniki, Greece; 3D Department of Surgery, Aristotle University of Thessaloniki, Thessaloniki, Greece; and Department of Pathology, Aristotle University of Thessaloniki, Thessaloniki, Greece

Correspondence:
Efstathios Kotidis, PhD
skotidis@gmail.com

Disclosure: The authors disclose no financial or other conflicts of interest.