Intermetatarsal bursitis as first disease manifestation in different rheumatological disorders and related MR-imaging findings

Metatarsalgia defined as pain at the plantar aspect of the forefoot. Intermetatarsal bursitis is considered one potential soft-tissue cause of metatarsalgia that is presumably under-estimated, under-investigated, and, consequently, often misdiagnosed. To assess the role of MRI in the elucidation of the cause of metatarsalgia in patients with different autoimmune disorders presenting primarily with this symptom and to present the accompanying clinical and radiological findings of intermetatarsal bursitis. Retrospective evaluation of the medical records of patients with different rheumatological conditions claiming primarily of pedal pains suggests metatarsalgia and who underwent, therefore, all magnetic resonance imaging between March 2010 and April 2018. Of them, six patients fulfilled these criteria and were diagnosed subsequently with intermetatarsal bursitis. Several underlying autoimmune conditions were diagnosed. All patients were clinically assessed by the squeeze test and radiologically investigated with MRI; three patients underwent additional sonography. All patients presented intermetatarsal bursitis as first disease manifestation. The number of involved bursae ranged from one to three on one side. The main MR findings were distension of the intermetatarsal bursa with increased signal intensity on T2-weighted and post-contrast fat saturation T1-weighted images. Most frequent locations were the second and third intermetatarsal spaces. The size of the intermetatarsal bursitis and its plantar extension were correlated in all patients. Intermetatarsal bursitis can potentially be the first manifestation of different rheumatological diseases. Awareness of this potential association as well as cognizance of its imaging findings can help for making a more accurate and prompt earlier diagnosis of the underlying disease changing also the therapeutic approach.