Age / Sex : 77 / M

Chief complaint : Pain on right ankle, with bulging around right lateral malleolus
- onset : 2 years ago

What is your diagnosis?

Two weeks later, you can see the final diagonosis with a brief discussion of this case (Please submit only one answer)

Courtesy : 김상운 (Sangun Kim), 고려대학교 안암병원 (Korea University Anam Hospital)

Tophaceous pseudogout (Tumoral CPPD)

Discussion

Disease definition
- Tumoral CPPD (or tophaceous pseudogout) is one of the rarest clinical forms of CPPD, characterized by CPPD crystal deposition that forms a solitary bulky mass in the joint, mimicking tophaceous gout, tumoral calcinosis, malignant or benign tumors.

Findings
Osteoarthritis of right ankle with joint space narrowing in medial tibiotalar joint.
Periarticular ligamentous calcifications near tibiotalar and talofibular joints.
Tumefactive soft tissue calcific deposit in lateral malleolus.

References
Tsuyoshi Ishida et al., Tophaceous pseudogout (tumoral calcium pyrophosphate dihydrate crystal deposition disease), Human Pathology 26(6) p587-593, 1995.
Antonio Catelli et al., Calcium pyrophosphate deposition disease: The role of imaging in their detection and in differential diagnosis of crystal arthropathies., Radiology Case Reports 15 (2020) 1773–1776