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Remote Fellowship – Foot & Ankle Fundamentals – 11/2/2020

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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.