CT manifestations of pulmonary mucormycosis: Influence of risk factor, symptom duration, and glycemic control

Pulmonary mucormycosis (PM) imaging has been characterised primarily in patients with hematologic malignancies. Imaging patterns may differ in diabetes mellitus-associated PM (DAPM), the most common risk factor globally, due to different immunologic profiles and disease progression. The impact of glycemic control on CT findings in DAPM is unknown.

We retrospectively analysed chest CT scans of patients with PM, compared DAPM with PM in other risk factors (PMOR), and evaluated imaging features across glycated haemoglobin (HbA1c) categories. The secondary objective was to determine associations between imaging features and mortality in DAPM. Imaging patterns recorded by two radiologists were compared between study groups, and multivariable logistic regression analysis of mortality was performed.

Among 193 patients (161 DAPM, 32 PMOR), consolidation (97%) and cavitation (84%) were the most frequent. DAPM presented significantly later (median 30 vs. 7 days; P < 0.001) and showed distinct features: smaller nodules (62%, <10 mm) with centrilobular distribution (37.4%), while PMOR had larger nodules (10-30 mm, 55.0%) with random distribution (75.0%). Lymphadenopathy was more common in DAPM (26.0% vs. 9.4%, P = 0.043). Among DAPM, Bird's nest sign increased with HbA1c severity: 7.7% (HbA1c ≤7%), 33.3% (HbA1c 7-9%), and 43.3% (HbA1c>9%), P = 0.030. Overall, 12-week mortality was 47.9%. Although the reversed halo sign and bird's nest sign were associated with mortality on univariable analysis, neither was significant after adjusting for clinical factors.

DAPM presents later and exhibits distinct imaging features compared to PMOR. Bird's nest sign is more frequent with HbA1c >9%. No imaging features were independently associated with mortality.