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Gonadal MRI in Complete Androgen Insensitivity Syndrome: Pathologic Correlation and Low-Risk Features
Rafael Loch Batista1,2,3, Filomena Marino Carvalho4, Fernando Morbeck Almeida Coelho5
1Developmental Endocrinology Unit, Hormone and Molecular Genetics Laboratory (LIM/42), Endocrinology Division, Internal Medicine Department, Medical School, University of São Paulo (USP), São Paulo, SP, 05403-000, Brazil.
Context:
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.
Objective:
To define multiparametric MRI features associated with absence of clinically relevant macroscopic gonadal neoplasia in postpubertal individuals with molecularly confirmed CAIS.
Methods:
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.
Results:
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.
Conclusion:
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.
Insights
Multiparametric MRI can identify low-risk gonads in individuals with complete androgen insensitivity syndrome (CAIS). Homogeneous signal, no diffusion restriction, and small gonadal volume suggest absence of neoplasia, supporting surveillance.
Area of Science:
- Radiology
- Oncology
- Endocrinology
Background:
- Complete androgen insensitivity syndrome (CAIS) management often defers gonadectomy post-puberty.
- This necessitates imaging strategies to differentiate low-risk gonads from those requiring intervention.
Purpose of the Study:
- To identify multiparametric MRI features predicting the absence of macroscopic gonadal neoplasia in postpubertal individuals with CAIS.
Main Methods:
- Retrospective analysis of 32 gonads from 16 postpubertal CAIS patients.
- Preoperative pelvic MRI, including diffusion-weighted imaging (DWI), followed by gonadectomy.
- Correlation of MRI findings with gonadal volume and histopathology.
Main Results:
- Homogeneous MRI signal and absence of diffusion restriction were 100% accurate in predicting the absence of macroscopic neoplasia.
- Neoplastic lesions were significantly larger (≥116.4 cm³) than benign gonads (≤21.9 cm³).
- Diffusion restriction in small gonads indicated Leydig cell hyperplasia, not neoplasia.
Conclusions:
- Homogeneous signal, absent diffusion restriction, and low gonadal volume on MRI can identify low-risk gonads in postpubertal CAIS.
- These findings support conservative surveillance for selected individuals.
- DWI interpretation requires caution in small gonads due to potential mimicry by Leydig cell hyperplasia.
