Ankle – Pigmented villonodular synovitis

CASE HISTORY

Injury one week previously presents with severe bruising and pain especially medially and along the calcaneus. No history of prior surgery. Please evaluate. 

TECHNICAL FACTORS

Long- and short-axis fat- and water-weighted images were performed. 

KEY IMAGES

This case has no key images.

CASE FINDINGS

• Moderate diffuse ill-defined subcutaneous edema throughout the medial aspect of the ankle extending to the calcaneus. In addition prominent soft tissue swelling of the dorsal soft tissues immediately superficial to the talar neck and anterior process. Within this region there is an approximately 1.5 x 1.5 x 1cm elliptical soft tissue mass-like area that more than likely represents hematoma. Subtle cortical irregularity of the adjacent anterior talar neck with remodeling consider localized PVNS or localized giant cell tumor of tendon. Ill-defined osteoedema within the adjacent anterior medial aspect of the tibia without macrofracture. 
• Undersurface fraying of the distal visualized portions of the anterior tibial tendon. The adjacent extensor hallucis and digitorum longus tendons are unremarkable. 
• The distal 2cm of the posterior tibial tendon are thickened and tendinopathic. No fluid in the tendon sheath. Flexor digitorum and hallucis longus tendons unremarkable. Superficial and deep components of the deltoid ligament intact as is the calcaneonavicular ligament. 
• Mild indistinctness of the anterior talofibular ligament with similar findings of the calcaneofibular ligament. The anterior and posterior tibiofibular ligaments are intact as is the tibiofibular syndesmosis. Peroneus brevis and longus tendons unremarkable. 
• Achilles tendon and visualized portions of the plantar aponeurosis are unremarkable. 
• Sinus tarsus and tarsal tunnel unremarkable.

CASE CONCLUSION

• Ill-defined soft tissue mass-like area along the dorsum of the ankle immediately adjacent to the talar neck. The appearance suggests a hematoma. Subtle cortical irregularity of the adjacent anterior talar neck with remodeling consider localized PVNS or localized giant cell tumor of tendon. A plain film with particular attention to the lateral view may aid in further characterizing this finding. In addition at least moderate ill-defined subcutaneous soft tissue swelling throughout the medial ankle with sprain of the adjacent medial retinaculum. 
• Undersurface frying of the distal portion of the anterior tibial tendon. 
• Tendinopathy of the distal 1.5cm of the posterior tibial tendon. 
• Mild strain/tear of the anterior talofibular and calcaneofibular ligaments. 
• Subtle contusion within the anterior medial aspect of the distal tibia without macrofracture. 
• Remainder of the examination unremarkable as described above.