Bone Abstracts

Chronic recurrent multifocal osteomyelitis (CRMO) is a rare, auto-inflammatory disorder of unknown cause that affects children and adolescents. CRMO is characterized by periodic bone pain, fever, multiple bone lesions occurring at any skeletal site, even if the metaphyseal area of long bones, clavicle and shoulder girdle are the most common locations. Dermatological manifestations include psoriasis, acne and pustules. The clinical and radiological features of the disease are variable and diagnosis can be difficult. Medical management includes nonsteroidal anti-inflammatory drugs, oral steroids and immunosuppressive drugs.

Two previously healthy boys, 13-year old (case 1) and 9-year old (case 2), with a recent diagnosis of CRMO, were referred to our department for a deeper evaluation of calcium metabolism and bone mineralization.

Case 1 had back pain, difficulty walking, and osteolytic lesions at right ulna and right trochanteric region. Case 2 had back pain, difficulty walking, skin lesions (pustules) on right leg, and osteolytic lesions at left femur and dorsal spine.

Both boys had been treated with oral steroids in the previous months with reduction of the osteolytic lesions.

Serum calcium, phosphate, magnesium, PTH and 25-OH vitamin D were normal for age. Phosphaturia was normal, calciuria was reduced. Bone turnover markers were moderately increased for age. Thyroid and gonadic function were normal. No other laboratory abnormalities were found.

Spine x-ray and MRI showed the presence of vertebral fractures: T₄ and T₆ in case 1; T₅ and T₆ in case 2.

Bone mineral density (BMD): case 1, spine z-score −0.6, femoral z-score −1.2 and total-body less head (TBLH) z-score −1.3; case 2, spine z-score −3.2; femoral z-score −2.1 and TBLH z-score −1,8.

Considering the presence of vertebral fractures, intravenous pamidronate (0.5 mg/kg, threee infusions in a week, once every 3 months) was started. After the second cycle, there was an improvement in both patients: pain disappeared, bone lesions and vertebral fractures stabilized, and walking was normalized.

A longer follow-up is needed to see the long-term effect on the disease and bone involvement (fractures and BMD).

Disclosure: The authors declared no competing interests.