1. Case M/23 C.C. : 1 st MTP joint pain (1YA)

2. 20070210 Foot AP/ sesamoid

3. 20061202 Outside CT (Rt. Foot)

4. Radiologic findings-CT Expansile osteolytic mass at medial sesamoid of hallux - with suspicious fracture lines -> DDx) 1. chondroblastoma or GCT 2. ABC 3. intraosseous gout Rec) Rt foot MRI using microcoil

5. 20070220 Foot MRI (Rt.)_Contrast T1 sagittal T1 sagittal (FS/Gd+) T1 coronal

6. 20070220 Foot MRI (Rt.)_Contrast T1 axialT2 axial T1 axial (FS/Gd+)

7. Radiologic findings-MRI Expansile mass involving medial sesamoid of hallux - peripheral irregular thick enhancement and central nonenhancing cystic or necrotic area - with its associated synovial enhancement of lst MTP joint - with bony erosion at lst metatarsal neck c reactive bone marrow edema -vascular structures anterior to the mass -closely abutting flexor hallucis tendon ->DDx) 1. intraosseous gout,most likely 2. tbc 3. tumorous condition such as giant cell tumor or chondroblastoma

8. Hospital course Op: Excision of Sesamoid, Rt.(2007-02-26) Pathologic diagnosis –Soft tissue, right foot, excision 1. Numerous rhomboid crystals showing birefringence 2. Some foci of calcium deposit 3. Chronic granulomatous inflammation with 1) multinucleated giant cells 2) central hyaline degeneration  consistent with calcium pyrophosphate dihydrate deposition disease

9. Calcium pyrophosphate dihydrate (CPPD) crystal deposition disease Etiology –Idiopathic: most common Increased with age (7% of population near age 70 and 30-60% by the age 80) –Hereditary: autosomal dominant condition Maybe associated with ANK(chromosome 5p15) –Secondary: 5-10% of patients have metabolic disease. Hyperparathyroidism, Hemochromatosis, Hypophosphatasia… Clinical patterns –Asymptomatic chondrocalcinosis –CPPD crystal arthropathy Pseudogout (18%), pseudo-osteoarthritis with/without synovitis (40%/18%), pseudorheumatoid arthritis (8%) Common location: Knee, wrist, MCP joint Seminars in musculoskeletal radiology 2003;07:175-186

10. Calcium pyrophosphate dihydrate (CPPD) crystal deposition disease Diagnositic imagings –Conventional radiography Calcification within or around joints –Chondrocalcinosis –Synovial and capsular calcifications –Other soft tissue calcification Findings of pyrophosphate arthropathy –Bilateral, symmetrical involvement of affected articulations –Cartilage loss, subchondral plate sclerosis, subchondral cyst formation –Subchondral collpase, fragmentation, intra-articular loose body –MRI Less dense calcium deposition->GRE sequence is more sensitive than conventional radiography. Seminars in musculoskeletal radiology 2003;07:175-186