Patient History
80-year-old man with a several-year history of a painful “lump” on the bottom of his left foot.
Findings
Skeletal/osseous:
No micro- or macro-trabecular fracture. No osseous contusion. No reactive pattern of marrow edema. Aggressive osseous abnormality.
Incidental partially segmental or bipartite tibial sesamoid. Unremarkable fibular sesamoid. No sesamoid osteoedema/sesamoiditis.
Articulations:
Unremarkable.
Lisfranc joint:
Intact.
Tendons:
Intact.
Ligaments:
Intact.
Plantar plates:
Intact.
Soft tissues:
Dumbbell-shaped intermediate T1 signal, intermediate to slightly increased T2 signal dumbbell-shaped soft tissue mass, wedged between the 3rd and 4th metatarsal heads (3rd intermetatarsal space), measuring 2.8 x 2.5 x 2.0 cm. The mass is centered around the plantar digital nerve region. Prominent enhancement post contrast is noted. Preservation of the adjacent metatarsal cortices (no aggressive features).
A similar, smaller, less florid process is seen between the 2nd and 3rd metatarsal heads within the 2nd intermetatarsal space (measuring 0.8 x 0.6 cm).
Peri-sesamoid soft tissue thickening/callus formation is seen.
Other:
Diffuse muscle atrophy and fatty infiltration involving intrinsic muscles of the forefoot, likely disuse atrophy versus diabetic amyotrophy.
Impressions
1. Giant M3-M4 Morton neuroma.
2. Smaller M2-M3 Morton neuroma/perineural fibrosis.
