Age / Sex : 9 / M

Chief complaint : left lower extremity trauma, incidental lesion


What is your diagnosis?

Two weeks later, you can see the final diagonosis with a brief discussion of this case (Please submit only one answer)

Courtesy : 정유미 (Yu Mi Jeong), 가천대 길병원 (Gachon University Gil Hospital)

Asymmetric(or delayed) closure of ischiopubic synchondrosis (=osteochondrosis of ischiopubic synchondrosis, =van Neck-Odelberg disease)

Discussion

Findings
1. Plain radiograph
- well-defined radiolucent bony enlargement at right ischiopubic junction
2. MRI
- fusiform enlargement of right ischiopubic synchondrosis, with bone marrow edema/enhancement and surrounding soft tissue edema

Discussion
1. Ischiopubic synchondrosis (IPS) is a temporary joint, occurring in childhood prior to fusion of the ischial and pubic bones. 
2. Considered to be a normal variant, can frequently be seen on conventional radiographs
3. In general, the fusion of the ischial and the pubic bones causes no symptoms.
4. In some children, pain in the groin and restriction in the movement of the hip joint
5. MRI :
Fusiform swelling of ischiopubic zone, with bone marrow signal alteration and enhancement, surrounding soft tissue edema
T1/T2-hypointense band at the synchondrosis, representing fibrous bridging
6. DDx : stress fracture, osteomyelitis, tumor, posttraumatic osteolysis

References
1. Sabir N, Çakmak P, Yılmaz N,et al. Osteochondrosis of Ischiopubic Synchondrosis: Van Neck–Odelberg Disease, J Pediatrics 2021;229:307-308.doi: 10.1016/j.jpeds.2020.09.027.
2. Herneth AM, Trattnig S, Bader TR, et al. MR imaging of the ischiopubic synchondrosis. Magn Reson Imaging. 2000 Jun;18(5):519-24. doi: 10.1016/s0730-725x(00)00138-7.