Ultrasound-Guided Diagnosis of Intermetatarsal Bursitis Mimicking Morton's Neuroma: A Case Report.

Metatarsalgia, a common cause of foot pain, significantly impairs quality of life and increases the risk of falls. Differentiating its underlying causes, such as Morton's neuroma and intermetatarsal bursitis, is crucial due to their distinct pathophysiology and management strategies. Clinical diagnosis can be challenging due to overlapping symptoms, underscoring the value of ultrasonography. This case report describes a 60-year-old woman with persistent metatarsalgia in the second and third interdigital spaces. While clinical findings suggested Morton's neuroma (positive Mulder test), ultrasound revealed a hypoechoic fluid collection measuring 8 × 4 mm with a thickened bursal wall, indicative of intermetatarsal bursitis, and, notably, no nerve thickening. This led to the exclusion of Morton's neuroma. The patient reported a pre-treatment Visual Analog Scale pain score of 8/10, which significantly improved to 2/10 following a steroid infiltration and custom insoles. This case highlights the importance of ultrasonography in accurately diagnosing metatarsalgia by differentiating between conditions with similar clinical presentations, thereby guiding appropriate treatment and improving patient outcomes.