[71] Massive Localized Lymphedema: A Clinicopathological Study of 21 Cases of a Still Poorly Recognized Pseudosarcoma Occurring in Morbidly Obese Patients

M Manduch, AM Oliveira, AG Nascimento, AL Folpe. Mayo Clinic, Rochester, MN

Background: Massive localized lymphedema (MLL) is a rare, relatively recently described pseudosarcoma most often occurring in morbidly obese patients. Owing to its rarity, MLL remains poorly recognized. In this large series of cases we further expand the spectrum of clinicopathologic features of this unusual entity, and emphasize its differential diagnosis from soft tissue neoplasms of various types.
Design: We performed a retrospective review of all cases diagnosed as MLL. All H and E stained sections were reviewed. Clinical information was obtained from the referring pathologists and clinicians.
Results: 21 morbidly obese adults (mean patient weight 186 kg/ 411 lb.) presented with unilateral, large soft tissue lesions of longstanding duration. The clinical history was also notable in 3 patients for previous inguinal herniorrhapy, multiple surgeries for scrotal edema, and hemiparesis secondary to gunshot trauma. Most lesions involved the proximal medial thigh (9) or thigh (6), but also occurred in the distal medial thigh (1), posterior thigh (1), posterior calf (1) and lower leg (3). Clinically, most lesions were regarded as representing benign processes, including pedunculated lipoma (6), lymphocele (1) or recurrent cellulitis (4), although soft tissue sarcoma was also suspected in 2 cases. Pathologists, however, regarded the majority of cases as potentially malignant, with suggested diagnoses including well-differentiated liposarcoma (WDL, 10), myxoid liposarcoma (1), and angiosarcoma (1). Grossly, all masses showed peau d'orange skin changes, and were ill-defined, unencapsulated, lobulated, and very large (mean size 31 cm, range 15 - 61.5 cm, mean weight 3386 gm, range 1133 - 10800 gm). Histologically, all 21 cases demonstrated striking dermal fibrosis, expansion of the fibrous septa between fat lobules with increased numbers of stromal fibroblasts, lymphatic proliferation and lymphangiectasia. Multinucleated fibroblastic cells (4), marked vascular proliferation (5), moderate stromal cellularity (4) and fascicular growth raised concern among referring pathologists for WDL, angiosarcoma, and a fibroblastic neoplasm in 10, 1, and 1 cases, respectively.
Conclusions: Many cases of MLL continue to be misdiagnosed by clinicians and pathologists as various types of soft tissue neoplasms, in particular WDL. Awareness of this entity, clinical correlation and gross pathological correlation are essential in the distinction of this distinctive pseudosarcoma from its various morphological mimics.
Category: Bone & Soft Tissue

Monday, March 9, 2009 1:00 PM

Poster Session II # 2, Monday Afternoon