1. HPI 48 yo F comes to the clinic complaining of left knee pain What questions would you like to ask?

2. HPI 2 month history of L knee pain, worse with ROM Reports noticeable L knee “stiffness” Recently noticed a “bump” behind the left knee - history of recent falls or trauma to the knee Denies other joint pain/discomfort

3. PMH: HTN, DM PSH: cholecystectomy Family Hx: colon cancer Social: social drinker, ½ pack/day smoker, denies illicits Meds: HCTZ, lisinopril Allergies: none Differential Diagnosis?

4. Differential Diagnosis Osteoarthritis Baker’s cyst Rheumatoid arthritis Ligamentous, meniscal injury Soft tissue/ bone tumor

5. PE Vitals: AVSS CV, Pulm, Abd: WNL Musc: Left knee exam: Fixed solid mass palpated over the posterior knee. No warmth, erythema appreciated. No joint line tenderness. Tender to palpation over posterior aspect of the knee. Decreased ROM (0- 90 degrees). Negative anterior/posterior drawer. Negative Mcmurray’s. Neurovascularly intact distal to R knee. Labs:WNL

6. Xray (AP)

7. Xray (Lateral)

8. MRI (T1) Coronal

9. MRI Sagittal

10. Histology

12. Giant Cell Tumor benign but aggressive tumor primarily found in the epiphysis of long bones Epidemiology Predominance in females ages 30-50 years 50% occur around the knee (distal femur or proximal tibia) 10% in sacrum and vertebrae (sacrum is most common site in axial skeleton) distal radius is third most common location Presentation: pain, decreased range of motion at the affected joint Malignant Potential: Metastatic to the lung in 2-5% Hand lesions have greater chance of metastasis 1.Orthobullets.com/pathology 2.Miller’s review of orthopaedics

13. Characteristic Features Xray eccentric lytic epiphyseal/metaphyseal lesion that often extends into the distal epiphysis and borders subchondral bone

14. Characteristic Features MRI clear demarcation on T1 image between fatty marrow and tumor

15. Bone scan is very “hot” Characteristic Features

16. Histology Characteristic cell is the mononucleur stromal cell hallmark giant cells are numerous nuclei of giant cell appears same as stromal cells