HPI• 48 yo F comes to the clinic complaining

of left knee pain

What questions would you like to ask?

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

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?

Differential Diagnosis

• Osteoarthritis• Baker’s cyst• Rheumatoid arthritis• Ligamentous, meniscal injury• Soft tissue/ bone tumor

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

Xray (AP)

Xray (Lateral)

MRI (T1)Coronal

MRI Sagittal

Histology

Histology

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/pathology2. Miller’s review of orthopaedics

Characteristic Features

• Xray• eccentric lytic epiphyseal/metaphyseal lesion that often extends

into the distal epiphysis and borders subchondral bone

Characteristic Features

• MRI • clear demarcation on T1 image between fatty marrow and tumor

• Bone scan is very “hot”

Characteristic Features

Characteristic Features

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