Herniated superficial lipomas in gluteal and thigh support areas: a special clinical ultrasound presentation

Lipomas are the most frequent benign tumor. They have been described as soft, well-defined, slow-growing palpable masses, and classified as deep or superficial.

To present the clinical and ultrasound findings of herniated superficial subcutaneous lipoma (HSL), located in pressure/support areas, not previously described.

A seven-year retrospective review was performed. Patients with a preoperative high-resolution ultrasound (HRUS) diagnosis of HSL archived in the computational system and histological study information were selected.

A total of 37 patients (mean age = 46 years) were recruited. The clinical diagnoses were "lipoma" or "suspected lipoma" in just 46% of the cases. This was three times more frequent in women. Tumors were located mainly in the gluteal (38%) and proximal thigh areas (35%). Clinically, all patients showed small, soft, rounded skin nodules. On HRUS, they appear as lipomatous tumors that protruded, compressed, and thinned the covering dermal layer. The subcutaneous portion was bigger than the herniated part, with an iceberg image.

HSL in support areas have a special clinical ultrasound presentation, not previously described. It is important to recognize them for a proper diagnosis and treatment, especially because they clinically may present as small superficial lesions; however, they are associated with a larger subcutaneous portion (iceberg image). It is probable that an estrogen influence on the adipose tissue can be suspected because of the female predominance.