Vertebral fracture characteristics are useful for distinguishing indolent systemic mastocytosis (SM) from primary osteoporosis, according to a scientific abstract recently published in the Annals of the Rheumatic Diseases.
One of the possible complications of SM is bone weakness. In about a fifth of patients, this manifests as spinal (vertebral) fractures. Anecdotal evidence suggests that a specific type of fracture called biconcave vertebral fractures are associated with indolent SM, but this has never been investigated in detail.
Investigators thus sought to assess the specific shape of vertebral fractures in indolent SM and investigate if this information may be useful in distinguishing this disease from primary osteoporosis, which is also often characterized by vertebral fractures.
The investigators in this study evaluated the clinical records of patients with indolent SM at a medical center in Italy. Specifically, they looked into patients who had at least one fragility vertebral fracture. The two types of vertebral fractures under investigation were biconcave fractures and wedge fractures. Both these fractures are characterized by their shape; biconcave fractures have the middle part collapsed inward, while in wedge fractures the front part of the vertebrae collapses, forming a wedge shape. As their names suggest, biconcave fractures have a biconcave appearance, while wedge fractures have a wedge-like shape.
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The research team discovered that patients with indolent SM had a significantly higher rate of biconcave vertebral fractures, while patients with osteoporosis more frequently had wedge fractures. In this study, more than 90% of patients with indolent SM had a combined total of more than 50% of biconcave fractures.
Furthermore, the region of the spine that was affected differed between patients with indolent SM and those with osteoporosis.
Statistical studies show that the number and percentage of biconcave vertebral fractures were sufficient to discriminate between patients with indolent SM and those with primary osteoporosis. The presence of at least two biconcave vertebral fractures had a high sensitivity (0.86) and specificity (0.84) for the correct classification of indolent SM in patients.
“[Indolent SM] patients have a higher number and rate of [vertebral fractures] with biconcave morphology than controls,” the research team concluded. “Vertebral fractures morphology and distribution can help discriminate [indolent SM] from primary osteoporosis.”
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