Season 7 Case 27

Season 7 Case 27

Case 27

History: 24 yo with knee swelling (be specific)


Answer:

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Parosteal Osteosarcoma

Dense ossified mass arising from the posterior metaphysis of the distal femur in a 20-ish yo person.

Classic age, Classic location, Classic appearance for parosteal type

Parosteal arises from the outer fibrous periosteum so sometimes you can see a slight cleavage plain between the mass and the cortex (not here).

Actually low grade so better than the classic osteosarcoma and the rarer periosteal type

ref: https://radiopaedia.org/articles/parosteal-osteosarcoma-1?lang=us