Rheumatoid nodule presenting as Morton's neuroma

Abstract

Among 101 feet that presented with symptoms and signs similar to Morton's neuroma, intermetatarsal rheumatoid nodules were found in five feet (three patients). Two patients had bilateral involvement. Histology of the excised tissue showed the presence of a rheumatoid nodule and Morton's neuroma in four feet and a rheumatoid nodule with unremarkable nerve bundles in one. A rheumatoid nodule can coexist with Morton's neuroma, as seen in our patients, and the presentation is often similar to that of a Morton's neuroma. Our patients were rendered asymptomatic with surgical treatment and went on to have appropriate management of rheumatoid arthritis. Rheumatoid nodule should be considered in the differential diagnosis of Morton's neuroma in not only rheumatoid arthritis patients but also asymptomatic patients who have never been tested for rheumatoid antibodies.

Fig. 1

Fullness in the second intermetatarsal space, with splaying of the surrounding toes

Fig. 2

Hematoxylin and eosin ×100. Central fibrinoid necrosis rimmed by palisaded fibroblasts and histiocytes indicating a rheumatoid nodule

Fig. 3

Hematoxylin and eosin ×25. Thickened blood vessels and nerve bundles that are rimmed by fibrous tissue consistent with Morton’s neuroma