Bilateral gynaecomastia as the sole presenting feature of a Y chromosome abnormality complicated by a gonadal tumour in an otherwise phenotypically normal male

¹ Departments of Medicine, University Hospital of Wales, Cardiff, Wales, UK
² Department of Genetics, University Hospital of Wales, Cardiff, Wales, UK
³ Department of Medicine, Llandough Hospital Cardiff, Wales, UK

We report the case of a 33-year-old male presenting with bilateral gynaecomastia whose karyotype was mosaic with 60% of the cells showing an isochromosome for the short arm of the Y chromosome and 40% showing 45,X complement. Further investigation revealed evidence of a stage one seminoma of the right testis and complete azoospermia. He was treated with bilateral orchidectomy and adjuvant radiotherapy and made an uneventful recovery. The case highlights the importance of cytogenetic investigation and appropriate testicular imaging in patients who present with gynaecomastia.