"The nomenclature of this entity is variable. Adverse reaction to metal debris is, as an umbrella term, sometimes interchanged with metallosis 4. More commonly, metallosis refers either to deposition of metallic wear debris (without specifying the nature of the tissue reaction) 1, or to the less aggressive end of the range of possible biologic reactions 2,5,6. See the separate article: metallosis."
"The soft tissue surrounding the implant appears thickened, fibrotic, and partly necrotic (often "cheesy" in texture) and may be discolored due to metallic deposits 6. There is variable fluid collection. Extensive reaction may form a solid and cystic mass, clinically termed a pseudotumour."
"Both ultrasound, CT and MRI can depict a pseudotumour as a mixed fluid/solid soft-tissue mass centred around the prosthesis and distending the trochanteric or iliopsoas bursa."