Working Diagnosis:
Adventitial bursitis of the left proximal medial thigh located medial to the ischial tuberosity and overlying the proximal attachment of the adductor magnus tendon.

Treatment:
The patient was advised to refrain from cycling for 6 weeks and subsequently begin a course of physical therapy. Because of the presence of possible fat necrosis, corticosteroid injection was not recommended.

Outcome:
The patient was advised to refrain from cycling for 6 weeks and subsequently begin physical therapy. She was referred to a sports-focused physical therapist with expertise in bicycle fitting and optimization for evaluation, bicycle fit recommendations, and therapeutic exercise instruction.

Because of the presence of possible fat necrosis, corticosteroid injection was not recommended.

The patient was ultimately lost to follow-up after these recommendations were provided.

Author's Comments:
Adventitial bursae develop in response to chronic friction, pressure, or repetitive shear forces and may occur in atypical anatomic locations. Although adventitial bursae differ histologically from native synovial bursae, often present with similar clinical symptoms and are managed using many of the same treatment principles, including activity modification, padding, anti-inflammatory measures, and physical therapy.

Editor's Comments:
This case highlights the importance of including adventitial bursitis in the differential diagnosis of focal soft tissue pain and palpable nodules in endurance athletes, particularly when symptoms correspond to areas of repetitive contact or pressure. Ultrasound was especially valuable in this case because it allowed dynamic assessment of the lesion, correlation with the patient's symptoms, and interval evaluation over time. As demonstrated here, ultrasound may provide greater clinical utility than magnetic resonance imaging for the diagnosis and monitoring of superficial adventitial bursae.

References:
1. Johnson DB, Varacallo MA. Ischial Bursitis. 2024 May 12. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2026 Jan. 2024 May 12. PMID: 29493912. https://www.ncbi.nlm.nih.gov/books/NBK482285/

2. Poenaru D. Cystic Degeneration of an Atypical Adventitial Bursitis: Case Report and Literature Review. Journal of Diagnostic Medical Sonography, 38(4), 365-368. http://dx.doi.org.proxy.library.upenn.edu/10.1177/87564793221076785

3. Sonographic Diagnostic of an Adventitial Bursitis on the Distal Forearm: A Case Report https://www.sdms.org/docs/default-source/jdmspdf/sonographic-diagnostic-of-an-adventitial-bursitis-on-the-distal-forearm-a-case-report.pdf?sfvrsn=2

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