692 - Pseudotumor Tensor Fascia Lata Syndrome From Underlying Severe Lumbar Stenosis

Case Diagnosis: Pseudotumor of the tensor fascia lata

Case Description: A 65-year-old man presented to a Physical Medicine and Rehabilitation clinic with acute-on-chronic right gluteal and sacroiliac joint pain. MRI of the lumbar spine showed moderately severe central stenosis at L4-L5 and foraminal narrowing at L3-L4 and L4-L5 bilaterally. The patient was diagnosed with chronic low back pain and treated with physical therapy, home exercise, and steroid injections resulting in symptom improvement. 
However, 15 months after the initial consultation, the patient reported new swelling and discomfort in the right lateral gluteal region. Diagnostic ultrasound revealed a large, well-demarcated soft tissue mass or hypertrophy along the tensor fascia lata (TFL) and gluteus muscles. Subsequent MRI of the hip revealed a large TFL with a diameter of 5.2 cm. Diagnosed with pseudotumor syndrome of the TFL, the patient underwent ultrasound-guided TFL chemodenervation with increasing doses of botulinum toxin injections, resulting in reduced muscle mass and improvement in pain over the TFL.

Discussions: We present a case of a 65-year-old male with hypertrophy of the TFL linked to both denervation from L4 radiculopathy and mechanical factors including altered gait mechanics. This case is significant as it adds to the limited body of existing literature describing TFL hypertrophy and its possible etiologies. There is substantial overlap in the clinical presentation of TFL hypertrophy and the more serious diagnosis of sarcoma. Therefore, increasing clinical awareness of the potential diagnosis of TFL hypertrophy or pseudohypertrophy in relevant cases is important. 

Conclusions: A pseudotumor of the TFL is a rare condition characterized by hypertrophy of the TFL, typically presenting as a mass in the anterolateral thigh and accompanied by localized pain. Clinical assessment and MRI characteristics are crucial for an accurate diagnosis. To limit unnecessary diagnostic testing and invasive procedures, clinicians should be aware of TFL hypertrophy and its possible etiologies.