Computed tomography (CT) scans could become a tool to help diagnose patients with systemic mastocytosis (SM), according to an article recently published in Scientific Reports.

“The technique allows noninvasive assessment of the mast cell burden and may therefore serve as a supplementary tool for diagnosis, subclassification and monitoring of the SM disease course,” the authors wrote.

This retrospective study included 18 patients of both sexes, aged 15 to 86 years, who were previously diagnosed with SM. The control cohort consisted of 18 individuals diagnosed with nonmetastatic malignant melanoma without any other hematologic neoplasm.

Each participant underwent dual-energy CT of the axial skeleton and evaluation of virtual-non-calcium attenuation values (VNCa-AV) in 5 representative vertebrae.

Read more about the diagnosis of SM

VNCa-AV was consistently elevated in patients with smoldering SM and advanced SM, with a mean of -9 HU, when compared to individuals from the control group (mean, -38 HU). Participants with indolent SM had the lowest values, with a mean of -54 HU.

Moreover, VNCa-AV showcased a clear association with the degree of mast cell infiltration in the bone marrow. A similar correlation occurred between VNCa-AV and tryptase levels in the blood.

Importantly, VNCa-AV could be a potential marker to identify advanced SM since 90% of the cases with values of -30 HU or higher corresponded to this subtype, and values above -10 HU were exclusively present in patients with advanced SM.

A theory that explains these findings states that hypercellularity could cause an abnormal elevation of VNCa-AV, especially since associated hematologic neoplasms could occur in up to 80% of patients with advanced SM.

“However, the strong association between VNCa-AV and several SM-specific factors outside of the bone marrow such as serum tryptase levels and to a lesser extent alkaline phosphatase, albumin and KIT D816V are clearly in favor of SM,” the authors noted.

Hence, it is more likely that the pathophysiology lies in the displacement of healthy adipose marrow by mast cells, Riffel and colleagues concluded.

Reference

Riffel J, Lübke J, Naumann N, et al. Functional imaging with dual-energy computed tomography for supplementary non-invasive assessment of mast cell burden in systemic mastocytosis. Sci Rep. 2022;12(1):14228. doi:10.1038/s41598-022-18537-6