A 40-year-old woman presented with chronic left anterior shoulder, upper arm, and axillary pain following a routine mammogram 3 years prior. Despite multiple interventions, her pain persisted significantly affecting her quality of life. Ultrasound examination revealed fascicular edema in the medial brachial cutaneous nerve (MBCN), intercostobrachial cutaneous nerve (ICBN), and a positive sono-Tinel. Ultrasound-guided hydrodissection of these nerves provided complete axillary pain relief and significant improvement in anterior arm pain, sustained for 6 months. This case highlights the diagnostic challenges of cutaneous nerve entrapment syndromes, often overlooked and misdiagnosed, especially without a clear inciting injury. Ultrasound proves superior to electrodiagnostic studies in visualizing nerve pathology, particularly in small cutaneous nerves. Incorporating ultrasound into the diagnostic process for nerve entrapments can reduce the need for more expensive tests like magnetic resonance imaging (MRI) with the added benefit of therapeutic intervention. Moreover, routine mammography should be considered a cause for ICBN and MBCN neuropathy, a rare but significant condition. Neuromuscular ultrasound offers distinct advantages in diagnosing and treating such neuropathies, exemplified by the successful management of our patient's condition.