Computed tomography-based radiological gynecomastia in SBMA as an independent differential diagnostic biomarker: a retrospective study

Spinal bulbar muscular atrophy (SBMA) and amyotrophic lateral sclerosis (ALS) are motor neuron disorders that demonstrate overlapping clinical features, especially in the early stage. Therefore, the aim of this study was to investigate the utility of chest tomography (CT) imaging in distinguishing between SBMA and ALS.

This was a retrospective study reviewing CT images from patients with SBMA and sporadic ALS and those in the control group. The CT images were assessed to measure the diameter and morphology of glandular tissue associated with gynecomastia. We compared CT-measured gynecomastia between the SBMA, ALS, and control groups. Additionally, correlation analyses were performed between the quantitative measurements of gynecomastia obtained from CT scans and various clinical/laboratory parameter in the SBMA group.

15 chest CT images were collected from SBMA, 41 from ALS, and 29 from control group. No statistical differences were observed in BMI, functional scales, or age at the time of CT scans between the SBMA and ALS groups. Despite similar functional scales and age in both groups, the mean glandular tissue diameter of breast tissue observed in chest CT imaging differed significantly between SBMA, ALS, and controls: 32.22 ± 12.57 mm, 15.91 ± 4.81 mm, and 15.76 ± 7.26 mm, respectively. This disparity allowed for the differentiation of SBMA from ALS and controls with statistical significance. Clinical gynecomastia was 80%, while radiological gynecomastia was 93.3% in SBMA. A significantly higher prevalence of diffuse glandular morphology pattern in SBMA (50%) was observed, contrasting with the predominance of nodular morphology in ALS and controls (9.1% and 20%). Correlative analysis between glandular tissue diameter and other clinical/laboratory parameters within the SBMA group showed no specific finding.

CT-based radiological gynecomastia effectively differentiated SBMA from ALS. These findings support the usefulness of radiological gynecomastia as a potential differential diagnostic marker for SBMA, especially in the early stages.