Ischiopubic synchondrosis (IPS) is a temporary joint that exists only in childhood, during bone maturation. On occasion it produces pain, whereas on others, it is an incidental finding revealed by plain radiography. Given its tumor-like aspect, it is necessary to perform magnetic resonance imaging (MRI) to differentiate it from pathological conditions.

The patient was an 8-year-old boy with no significant medical history. He reported that, for the last year, he was having weekly episodes of intense pain in right lower limb that lasted at least an hour. The pain was located in anterior aspect of his thigh and gluteal region, and limited his mobility. He had no fever or constitutional symptoms. The clinical signs and symptoms remitted with rest and the usual analgesics.

Physical examination confirmed that the child was obese (body mass index=24; >97th percentile). There was no evidence of inflammation, limitation of mobility or neurological deficits. Complete blood count, laboratory tests and acute-phase reactants were normal.

An anteroposterior radiograph of the pelvis (Fig. 1) revealed enlargement of right-sided IPS, with small irregularities of pseudotumoral aspect. Magnetic resolution produced (Fig. 2) an asymmetrical and irregular image, like a “fibrous bridge”, affecting right ischiopubic syndesmosis (T1) and a hyperintense signal with associated soft-tissue edema in T2-weighted and short tau inversion recovery (STIR) sequences. This is all compatible with a diagnosis of “Van Neck-Odelberg osteochondritis”.

Fig. 1.

Anteroposterior radiograph of pelvis: swelling of right ischiopubic synchondrosis.

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Fig. 2.

Axial magnetic resonance imaging (short tau inversion recovery) of pelvis: swelling of right ischiopubic synchondrosis, with irregular margins. Signal alteration in bone marrow and edema of the surrounding soft tissue.

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Van Neck-Odelberg disease is a benign process that develops in children between the ages of 4 and 16 years. It is characterized by pain in the lower limb due to osteochondritis of the ischiopubic ramus.1,2

There is swelling of the IPS with no clinical manifestations, but it can be associated with pain in the thigh, groin region or buttock, with limitation of the mobility of the extremity and limping.3

Plain radiography usually shows an enlargement of the synchondrosis with radiolucent and osteolytic areas. The typical MRI findings include changes in bone marrow and perilesional soft-tissue edema.2–4

The tumor-like appearance in radiographs may lead to a diagnosis of stress fracture, an infectious process or tumor.1–5 The absence of fever and normal results on laboratory tests facilitates the differential diagnosis.1

This condition usually has a favorable outcome after 2 or 3 weeks of anti-inflammatory therapy and rest.2,3,5,6

The authors declare they have no conflicts of interest.