Aims A nine-year-old girl with Chronic Recurrent Multifocal Osteomyelitis (CRMO) developed asymptomatic bilateral pulmonary consolidation that was thought to be part of the CRMO disease process. Approximately 25% of patients with CRMO have another inflammatory disorder; usually of the skin or gastrointestinal tract. The association of CRMO with pulmonary lesions has been reported only twice in the literature. This case is the first reported in which lung infiltrates were successfully treated with azithromycin.
Methods The patient presented with nine-months of right leg pain. MRI showed an area of high signal in the right femoral diaphysis. Biopsy was negative for pathogens and malignancy. She developed painful swelling of the right clavicle and spinal discomfort. An isotope bone scan showed abnormal uptake in both clavicles and one vertebral body and CMRO was diagnosed. She responded to ibuprofen but symptoms returned. Repeat isotope bone scan showed improved appearances at the bony sites, however low resolution CT scan performed as part of this showed bilateral pulmonary infiltrates. Chest radiographs showed left mid-zone consolidation. After four months this resolved but new infiltrates were seen in the left apex and right upper-zone. There were no clinical features of infection, serum C-reactive protein and white cell count were normal. She was given azithromycin for 4 weeks in view of its known anti-inflammatory properties; in one study seven of thirteen patients with CRMO showed a rapid clinical improvement in bone lesions when given azithromycin.
Results Radiographs taken 2 and 6 months after azithromycin found near complete resolution of the pulmonary abnormalities. She received eight pamidronate infusions and symptoms resolved except for clavicular discomfort. Inflammatory bone lesions resolved on pelvic MRI. The two previous cases of pulmonary involvement in CRMO received prolonged antibiotics for two  and six months .
(A) Axial proton density MRI image through right thigh showing cortical high signal lesion (arrow) with evidence of marrow oedema. (B) Clinical photograph demonstrating bony prominence of the medial ends of each clavicle. (C) Coronal CT image of the thorax demonstrating bilateral pulmonary infiltrates. (D) Anterior view only from isotope bone scan showing increased activity arising from both clavicles. The right femoral lesion can just be appreciated. (E) Chest radiograph showing left midzone infiltrate. (F) Chest radiograph demonstrates new infiltrates at left apex and right mid zone (G) Chest radiograph taken two months following completion of azithromycin therapy demonstrating near complete resolution of the pulmonary infiltrates.
Conclusions Our observations of pulmonary involvement add to the understanding that CRMO is a heterogeneous disease; it is likely that such prolonged and atypical pulmonary changes are part of the disease process of CRMO. Pulmonary consolidation is a rare complication of CRMO, should be looked for in patients with refractory disease and may respond to azithromycin.
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