A 47-year-old woman comes to the physician with foot pain for several months. Pain occurs in the ball of her right foot between the 3^rd and 4^th toes. It is especially intense when she wears high heels or drives. She often has the sensation of stepping on a marble just beneath her toes. She normally walks 2-3 miles about 3 times a week for exercise but the discomfort has prevented her from doing so. She has no history of foot trauma and the pain does not bother her at night. She has no other musculoskeletal symptoms.
Her other medical problems include type 2 diabetes mellitus and hypertension.
Her blood pressure is 134/84 mm Hg and pulse is 76/min. BMI is 30 kg/m². Foot examination reveals bilateral full and symmetric pulses and small bunions. There is unilateral pain to deep palpation at the base of the web space between the 3^rd and 4^th toes on the right. No lesions are palpable. Foot sensation to light touch, position, and tuning fork is normal. There are no obvious deformities of her feet and ankles. Range of motion of her ankles and toes is normal.
X-ray of the foot show no abnormalities.
What is the most likely diagnosis?

Question

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11ec193a_987d_2b59_853d_278f34a79cef_MD0002_00 This patient's presentation is consistent with Morton's neuroma (interdigital nerve compression). This condition is common in women who wear high-heeled shoes, runners, and people with flat feet. Repetitive injury leads to painful enlargement of the plantar digital nerve between the metatarsal heads. Patients complain of numbness and burning pain. Pain is located along the plantar aspect of the forefoot, usually between the 3^rd and 4^th metatarsals. ^rd ^th Treatment involves conservative measures such as orthotic footwear and NSAIDs. Corticosteroid injections can be used for symptomatic relief in patients who fail conservative measures. Surgical excision can be performed for patients who fail all such therapy and remain symptomatic after 1 year. (Choice A) Charcot joint results from progressive degenerative joint disease due to peripheral neuropathy. Physical examination usually shows swelling, erythema, and loss of sensation near the involved joint. This patient has no such signs. (Choice B) Patients with diabetic neuropathy complain of pain, paresthesias, or dysesthesias. Examination shows impaired pain sensation, light touch, and vibratory and position sense. (Choice C) Metatarsal stress fracture occurs in runners due to repetitive stress injury. Examination shows focal point tenderness near the metatarsal shaft. Differentiating a stress fracture from Morton's neuroma can be difficult. Stress fractures may not be seen on plain films during the first 2 weeks after injury; however, this patient has had symptoms for several months and a fracture would have been visible. (Choice E) Plantar fasciitis usually results in heel pain and would be an unusual cause of forefoot pain. Educational objective: Morton's neuroma (interdigital nerve compression) results from painful enlargement of the plantar digital nerve between the metatarsal heads. Patients complain of burning pain and numbness usually between the 3^rd and 4^th metatarsals. Treatment is conservative. ^rd ^th __________ References: Interventions in the treatment of Morton's neuroma. (http://www.ncbi.nlm.nih.gov/pubmed/15266472) Morton's interdigital neuroma: a clinical review of its etiology, treatment and results. (http://www.ncbi.nlm.nih.gov/pubmed/8722878)

A 47-Year-Old Woman Comes to the Physician with Foot Pain