Central Metatarsalgia and Walking on Pebbles: Beyond Morton Neuroma

Central metatarsalgia relates to abnormalities of the second, third, and fourth metatarsals and their respective metatarsophalangeal joints. A variety of disorders present with central forefoot pain; they range from traumatic lesions (acute or chronic repetitive), inflammatory and infective disorders, nonneoplastic soft-tissue lesions, and benign tumors to malignant lesions. Patients often present with symptoms of localized pain in the forefoot that worsens on weight bearing (walking or running), which can be sharp or dull and often is perceived as a lump felt inside or underneath the foot and described as walking on a marble or pebbles. These patients are labeled as having central metatarsalgia and are further evaluated with ultrasound or MRI to establish a diagnosis. In this article, we review metatarsal and intermetatarsal lesions of the foot that present with central forefoot pain and a sensation of walking on pebbles, focusing on conditions mimicking Morton neuroma clinically or on imaging. We also briefly review some other plantar lesions and arthropathy that can present with awareness of lump underneath the foot.