Adrenal and juxta-adrenal schwannomas: A single-centre study

Objective: Adrenal schwannomas and juxta-adrenal schwannomas are rare tumours. We aimed to summarise their clinical, biochemical and imaging characteristics. Design: Single-centre retrospective study of eligible patients between 1995 and 2022. Patients and Measurements: Patients with a histopathologic diagnosis of adrenal or juxta-adrenal schwannoma. Results: Twenty-four patients were diagnosed with either primary adrenal schwannoma (8, 33%) or juxta-adrenal schwannoma (16, 67%). Most tumours (21, 88%) were discovered incidentally on imaging. All tumours were unilateral, with 15 (62%) on the left and 9 (38%) on the right. At diagnosis, the median tumour size was 4 cm (range, 2–13 cm). Adrenal schwannomas were smaller when compared to juxta-adrenal schwannomas (median of 3.1 cm [range, 2–9 cm] vs. 4.6 cm [range, 2.3–13.3 cm], p =.037). On imaging, the tumours were round or oval in shape in 16 (70%), lobulated in 7 (30%), solid in 15 (68%), solid-cystic in 7 (32%), heterogeneous in 14 (61%) and homogeneous in 9 (39%). The median unenhanced computed tomography attenuation was 30 Hounsfield units (HU) (range, 12–38 HU). Of the 20 patients who underwent complete hormonal testing, all had nonfunctioning tumours. There was no recurrence or new tumour development in our cohort. Conclusions: Adrenal and juxta-adrenal schwannomas are nonfunctioning benign tumours that present with indeterminate radiographic features, including large tumour size and increased unenhanced CT attenuation. We did not find an imaging phenotype that was diagnostic of schwannoma. The diagnosis of this rare tumour is based on biopsy or resection.