The nidus mineralization ratio of osteoid osteomas increases significantly with pain duration and may be a marker of tumor age, according to a study published in the June issue of Radiology.

Osteoid osteomas have a complicated pathophysiology and natural history, and diagnosis is based on the identification of a typical nidus at cross-sectional imaging. Lead author Sebastien Touraine, MD, of Hôpital Lariboisière in Paris, and colleagues aimed to assess the morphologic changes of osteoid osteomas in association with the patients’ pain duration by studying a series of patients with pathologically proven osteoid osteomas.

During the study, the researchers assessed age, sex, bone location, bone segment, location of the osteoid osteoma in relation to the native cortex, nidus area, nidus calcification area and attenuation at CT in 96 patients.

A significant increase between the patients’ age and nidus mineralization ratio with pain duration was observed, as the hazard ratios were 0.975 and 0.193, respectively. No significant association was discovered between pain duration and other variables, including the nidus area.

In long bones, diaphyseal osteoid osteomas were significantly less mineralized than those in other locations.

The mean duration of pain before the day of treatment was 17.24 months, and was not significantly different according to sex or location of the osteoid osteoma in relation to the native cortex.

Given the study’s results, the researchers believe the nidus mineralization ratio could represent a marker of the age of the osteoid osteoma and should be considered when conservative treatment is discussed.

However, “Further studies are needed to determine if the nidus mineralization ratio represents an important element in deciding between interventional and conservative treatments, especially in critical locations or when the patient declines the percutaneous ablation,” wrote the authors.