Massive localised lymphoedema (MLL) is a rare, relatively recently described pseudosarcoma most often occurring in morbidly obese patients.
To perform a retrospective review of all cases diagnosed as MLL.
Clinical information was obtained. 22 morbidly obese adults (mean patient weight 186 kg) presented with unilateral, large soft tissue lesions of longstanding duration. Most lesions involved the thigh, but also occurred in the posterior calf and lower leg. Clinically, most lesions were regarded as representing benign processes, including pedunculated lipoma, lymphocoele or recurrent cellulites, although soft tissue sarcoma was also suspected in two cases. Grossly, all masses showed markedly thickened skin with a "cobblestone" appearance, and were ill-defined, unencapsulated, lobulate, and very large (mean size 31 cm, range 15-61.5 cm, mean weight 3386 g, range 1133-10,800 g). Histologically, all 22 cases showed striking dermal fibrosis, expansion of the fibrous septa between fat lobules with increased numbers of stromal fibroblasts, lymphatic proliferation and lymphangiectasia. Multinucleated fibroblastic cells, marked vascular proliferation, moderate stromal cellularity and fascicular growth raised concern among referring pathologists for atypical lipomatous tumour/well differentiated liposarcoma, angiosarcoma, and a fibroblastic neoplasm such as fibromatosis in 10, 2 and 1 case, respectively.
The diagnosis of MLL continues to be challenging, in particular for pathologists. Awareness of this entity, clinical correlation and gross pathological correlation are essential in the separation of this distinctive pseudosarcoma from its various morphological mimics.