Lipomatosis of Nerve Misdiagnosed as Primary Lymphedema: Report of Two Cases

Abstract

Primary lymphedema (i.e., a chronic condition characterized by the accumulation of protein-rich fluid in the interstitial spaces due to impaired lymphatic drainage) and lipomatosis of nerve (LN) (i.e., a congenital lesion characterized by the presence of fat interspersed within nerve) can involve a significant overgrowth of the affected limb, but their pathophysiology and treatment are totally different. This report addresses the misdiagnosis of both entities. The purpose is to highlight how both entities can be differentiated through two case reports. The first patient, a 69-year-old man, presented in our lymphedema clinic with multiple debulking operations; he was diagnosed with right upper extremity lymphedema during childhood. The thumb, index, and middle fingers had previously been amputated due to sequelae from the bony overgrowth. MRI of the right upper extremity showed pathognomonic features of LN affecting the median nerve associated with soft tissue fatty overgrowth. He had a 3 months follow-up for this condition in our institution during which his symptoms remained stable. The second patient, an 81-year-old man, presented in our lymphedema clinic. He carried a long time diagnosis of primary left lower extremity lymphedema and had been followed at our institution for more than 25 years. Physical examination revealed overgrowth (increased volume) affecting the entire leg and foot. MRI showed pathognomonic features of LN of the left sciatic nerve. No surgical interventions were performed. At the last follow-up, his extremity showed slightly worsened diameter measurements. Based on our 2 cases presented and 2 additional cases identified in the literature, we believe that primary lymphedema and LN are two different entities that could be confused. Plastic surgeons treating patients with lymphedema should be aware of LN and rule out this condition clinically and with imaging (US or MRI).