title: Tophaceous calcium pyrophosphate dihydrate deposition disease of the knee mimicking an aggressive soft tissue tumour.
abstract: Calcium pyrophosphate crystal deposition disease (CPPD), previously pseudogout, is the second most common crystal arthropathy after gout. There is increased radiographic prevalence associated with age, trauma and several metabolic disorders. Tophaceous CPPD (T-CPPD) is a rare form of CPPD which, though non-neoplastic, mimics a bone or soft tissue malignancy. T-CPPD usually presents as a mass in the temporomandibular joint and occasionally in the paraspinal tissues, but rarely in the joints of the extremities. We present an exceptionally rare case of T-CPPD that was subtle on plain radiography, presenting as a soft tissue mass in the knee joint.
authors.affiliation: Department of X-ray, Royal National Orthopaedic Hospital NHS Trust, Middlesex, Stanmore, UK.
authors.forename: Christopher
authors.initials: C
authors.lastname: Watura
authors.affiliation: Department of X-ray, Royal National Orthopaedic Hospital NHS Trust, Middlesex, Stanmore, UK.
authors.forename: Asif
authors.initials: A
authors.lastname: Saifuddin
mesh_terms: D002805:Chondrocalcinosis / Q000175:diagnosis*; D003937:Diagnosis, Differential; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000473:pathology*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D012983:Soft Tissue Neoplasms / Q000175:diagnosis*; D014057:Tomography, X-Ray Computed