Case Report of Painful Nodules in Lipedema: Correlation between Qualitative Ultrasonographic Classification and Histological Findings

Lipedema is a chronic and progressive condition characterized by the disproportionate accumulation of subcutaneous adipose tissue predominantly in the upper and lower limbs, sparing the trunk, hands, and feet. It affects approximately 12.3% of the female population in Brazil. Clinically diagnosed, its most common symptoms include tenderness upon palpation and spontaneous bruising. During the development of a qualitative ultrasonographic classification for lipedema, termed Lipedema Dermis and Hypodermis Classification (LDHC), an echogenic nodule was identified in the superficial hypodermis. This nodule was painful upon superficial palpation and lacked ultrasonographic features of a lipoma. The patient presented with a nodule in the distal posterior region of the right thigh and another on the distal posterior of the right arm. Given the possible differential diagnoses, including neoplasia and angiodysplasia, an ultrasound-guided biopsy was performed. Macroscopic analysis revealed an oval-shaped, reddish nodule, suggestive of blood content. Histological analysis revealed areas of steatonecrosis, hemorrhagic foci, and neoangiogenesis with irregular architecture and fragile vessel walls. Complementary analysis of the resistance index (RI) of superficial hypodermal arteries demonstrated an increased RI in the lipedema patient compared to the control. All these findings suggest that the tissue is hypoxic and characterized by chronic inflammation, supporting the hypothesis of increased subcutaneous compartment pressure in lipedema. This case report elucidates the ultrasonographic findings of nodules classified by LDHC through microscopic anatomical correlation and aids in understanding the pathophysiological mechanisms underlying lipedema.