Chronic recurrent multifocal osteomyelitis (CRMO) is a rare auto-inflammatory disease affecting children and adolescents, characterized by relapsing and remitting pain related to the presence of foci of sterile bone inflammation. Diagnosis is often challenging because it presents with an insidious onset of signs and symptoms usually without objective findings.
Imaging is essential for diagnosis and bone scintigraphy (BS) has shown to be an excellent tool for identifying both symptomatic and silent sites of disease and for monitoring disease activity during therapy and follow-up.
Aim of our work is to underline role and feasibility of BS in diagnostic assessment of children with suspected CRMO, supporting subsequent patient management.
Among 115 BS performed in 47 consecutive children (22 males, median age at presentation 9 years, range 1-18) treated at our Institution for CRMO from 2004 to 2014, we retrospectively evaluated each patient’s first BS, performed during diagnostic workup, for a total of 48 BS. All patients underwent two-phase whole-body BS, consisting in a blood pool whole-body scan (BP-BS), acquired over 5 min after i.v. 99mTc-MDP injection, and a late whole-body scan (L-BS) three hours later. Sedation was not administered in any patient. Clinical features and other imaging findings were recorded.
At onset, 15/47 (32%) patients had history of localized bone pain and 32/47 (68%) had multifocal symptoms; 35/47 (74%) patients presented limited mobility. Plain radiography was performed in 23/47 (49%), ultrasonography in 18/47(38%), segmental MRI in 38/47 (81%) and whole-body MRI in 3/47 (1%) patients, respectively.
39/47 (83%) BP-BS were positive. Most frequently involved sites were ankle (9/39, 23%; 2/9 bilaterally), femur, tibia and sternoclavicular joint (6/39; 15%) respectively.
All L-BS were positive but one; most frequently involved sites were tibia (24/46, 52%; 8/24 bilaterally) and femur (15/46, 33%; 6/15 bilaterally), predominantly the metaphyses.
There was correspondence between radiotracer uptake at L-BS and symptomatic sites in all 15 patients with localized bone pain, but one, who showed no uptake at both BP-BS and L-BS. In this patient, a CT scan showed a lytic lesion in the heel and histologic examination revealed a sub-acute inflammatory pattern; moreover, in 7/15 (47%) patients L-BS scan revealed additional pathological lesions, suggesting multifocal disease and supporting diagnosis.
In patients with multifocal bone pain, L-BS allowed to identify more accurately lesions site and helped in identification of active lesions accessible for biopsy in 24/32 (75%) patients.
Diagnosis was histologically confirmed in 37/47 (79%) patients, while in 10/47 (21%) patients, it was based on clinical course, image findings and response to therapy.
Our ten-year experience confirms BS as a useful and simple tool in the detection of CRMO lesions, both in patients with unifocal and multifocal disease.