Gonadal MRI in Complete Androgen Insensitivity Syndrome: Pathologic Correlation and Low-Risk Features.

Abstract

In complete androgen insensitivity syndrome (CAIS), gonadectomy is increasingly deferred until after puberty, creating a need for imaging-based strategies that distinguish low-risk gonads from those warranting surgical intervention. To define multiparametric MRI features associated with absence of clinically relevant macroscopic gonadal neoplasia in postpubertal individuals with molecularly confirmed CAIS. We retrospectively evaluated 32 gonads from 16 postpubertal individuals with molecularly confirmed CAIS who underwent preoperative pelvic MRI, including diffusion-weighted imaging, followed by bilateral gonadectomy. MRI findings were reviewed by expert radiologists and correlated with gonadal volume and histopathologic assessment. Macroscopic neoplasia was identified in three patients and included seminoma with adjacent germ cell neoplasia in situ, a large-cell calcifying Sertoli cell tumor, and a serous borderline tumor of Müllerian type. Homogeneous MRI signal and absence of diffusion restriction were each associated with absence of macroscopic neoplasia and yielded a negative predictive value of 100% in this cohort. Gonadal volume also separated benign from neoplastic lesions: all non-neoplastic gonads measured ≤21.9 cm3, whereas all neoplastic lesions measured ≥116.4 cm3. False-positive diffusion restriction occurred only in small gonads and corresponded histologically to Leydig cell hyperplasia. In postpubertal CAIS, homogeneous signal, absence of diffusion restriction, and low gonadal volume may identify gonads at low risk for macroscopic neoplasia and support conservative surveillance in selected individuals. Diffusion-weighted imaging on MRI should be interpreted cautiously, particularly in small gonads, where Leydig cell hyperplasia may mimic neoplasia.