Imaging description

A 17-year-old presented with a rapidly enlarging right hip mass after a fall while skateboarding. An MRI was obtained which demonstrated a fluid collection between the subcutaneous tissues and underlying fascia of the right hip. The fluid collection was hypointense on T1-weighted images and contained a hyperintense lobule of fat (Fig. 94.1a). On T2-weighted images with fat suppression, the fluid was hyperintense and the lobule of fat demonstrated suppressed, hypointense signal (Fig. 94.1b). The appearance was considered to be compatible with a Morel-Lavallée lesion. Conservative management was offered, with eventual resolution of the lesion.

A two-year-old male presented with a left thigh mass two weeks after having his left thigh pinned beneath a wheel of a truck. Initial radiographs were negative for osseous fractures. An ultrasound demonstrated an anechoic fluid collection with debris and septations (Fig. 94.2a). A subsequent MRI revealed a fluid collection beneath the subcutaneous tissues and overlying the fascia of the medial left thigh, compatible with a Morel-Lavallée lesion. The fluid collection was noted to be hypointense on T1-weighted images (Fig. 94.2b) and hyperintense on T2-weighted sequences (Fig. 94.2c, d). Rim enhancement was noted (Fig. 94.2e). This lesion similarly resolved with conservative management.