Patient History

56-year-old woman with previous injury to the peroneal tendons now complaining of chronic foot/ankle pain.

Findings

SKELETAL/BONES:

Pressure erosions throughout the ankle, most prominent at the dorsal aspect of the talus and inferior talus surrounding the sinus tarsi. Further smaller pressure erosion posterior distal fibular tip.

No aggressive osseous abnormality. No reactive osteoedema, micro- or macro-trabecular fracture.

ARTICULATIONS:

Tibiotalar joint/talar dome: Extensive metaplastic tumefactive synovial thickening throughout the entire ankle, most pronounced laterally, anterolaterally and anteriorly, with innumerable scattered low signal foci of siderosis, consistent with PVNS.

Ankle mortise/syndesmosis: The ankle mortise is in anatomic alignment. No syndesmotic widening.

Chopart joint: Tumefactive synovial thickening with foci of susceptibility/siderosis through the sinus tarsi and adjacent to the posterior facet of the subtalar joint.

Midfoot/hindfoot: No fracture or injury of the anterior calcaneal process. No prominent midfoot or hindfoot arthrosis.

LIGAMENTS:

High ankle: Completely insinuated and obscured by the metaplastic tumefactive synovial mass.

Low ankle: Completely insinuated and obscured by the metaplastic effective synovial mass.

Subtalar/Chopart: Intact.

TENDONS:

The metaplastic tumefactive synovial mass completely encases the peroneal tenosynovial complex, containing the tendons within it, extending from 5 cm above the fibular tip to approximately 2 cm proximal to the peroneus brevis tendon insertion at the base of the 5th metatarsal. Total craniocaudal extent of the mass is approximately 10 cm length.

Otherwise intact extensor, flexor and Achilles tendons.

GENERAL:

Sinus tarsi: Tumefactive synovial thickening throughout the sinus tarsi with adjacent talar pressure erosion.

Muscles: Unremarkable.

Soft tissue: Bimalleolar soft tissue edema.

Plantar fascia: Diffuse mildly to moderately thickened central cord of the plantar fascia, consistent with chronic plantar fasciitis. No evidence for active plantar fasciitis.

Neurovascular complex/tarsal tunnel: Unremarkable. No evidence of entrapment neuropathy.

Intra-articular/loose bodies: None.

Discussions

  1. Massive PVNS involving the ankle joint, subtalar joint and peroneal longus and brevis tendons/tendon sheaths. Mass measures approximately 10 cm in craniocaudal dimension.
  2. Complete encasement/involvement of the peroneal tenosynovial complex.
  3. Prominent pressure erosions surrounding the ankle joint and sinus tarsi.