Massive localized lymphedema ("lymphedema pseudotumor") is a rare condition in which a large soft tissue mass forms at the site of long standing lymphedema. It may occur in association with obesity.

The section shows subcutaneous tissue with abundant capillary and small arteriolar insularity, along with zones of fibrosis encasing lobules of fat filled with spindled to polygonal stromal cells with plump dark nuclei. Numerous scattered mast cells are also present.

Immunohistochemistry demonstrates the following findings within the fibrous spindle cells: CD34+, CD31+, SMA-, desmin-, PanK-, CK14-, p63-, beta catenin-, c-myc-, MDM2 (cytoplasmic only), ER-, S100-.

It is important to exclude adipocytic neoplasms in such a case. In this case, the presence of skin changes and lack of nuclear MDM2 over-expression is reassuring. In addition, the proliferation, atypia, and other changes of lymphedema associated vascular lesions are not identified.

Massive localized lymphedema has a mostly benign clinical course, with most complications arising from the comorbidities that are often present in such cases. The goal of lymphedema therapy is to restore function, reduce physical and psychological suffering, and prevent the development of infection. In secondary lymphedema, the underlying etiology (neoplasm, infection) should also be properly treated in order to relieve the lymphatic obstruction. The pharmacological therapy includes benzopyrones, retinoid-like agents, anthelmintic agents, and antibiotics (eg, cefazolin, clindamycin, penicillin G). Conservative measures for managing lymphedema include the following: maintenance of appropriate hygiene and skin care, use of complex physical therapy (first-line treatment) and compression stockings, weight loss (if overweight), and avoiding trauma.

See related content for references:

1) Kurt et al., Mod Pathol 2016;29:75-82