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Klinefelter syndrome presenting as metastatic bilateral breast cancer: missed diagnostic opportunities
  1. Roxana Maria Tudor1,2,
  2. Elsheikh Mohammed Ali1,
  3. Salman Ullah Khan3 and
  4. John McDermott1,2
  1. 1Academic Department of Endocrinology and Diabetes, Connolly Hospital Blanchardstown, Dublin, Ireland
  2. 2Royal College of Surgeons in Ireland, Dublin, Ireland
  3. 3General Internal Medicine Department, Mater Private Dublin, Dublin, Ireland
  1. Correspondence to Dr Roxana Maria Tudor; roxanamariatudor21{at}


Klinefelter syndrome (KS) is the most common cause of primary hypogonadism in male patients; however, the diagnosis of KS is frequently delayed or missed. This delay can lead to undesirable outcomes for patients, especially considering that individuals with KS have a higher risk of developing specific malignancies, including breast cancer, non-Hodgkin’s lymphoma and mediastinal germ cell tumours. We present a case of a male patient in his 60s, where the established diagnosis of metastatic bilateral breast cancer prompted us to investigate and subsequently confirm a diagnosis of KS. This case highlights the diagnostic challenges of KS and emphasises the unfavourable consequences of a delayed diagnosis. We aim to raise awareness and enhance physicians’ understanding of KS and its non-reproductive manifestations, with a view to promote early recognition and improve patient outcomes.

  • Genetics
  • Reproductive medicine
  • Breast cancer

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  • Contributors The following authors were responsible for drafting of the text, sourcing and editing of clinical images, investigation results, drawing original diagrams and algorithms, and critical revision for important intellectual content: RMT, JM, SUK and EMA. The following author gave final approval of the manuscript: JM.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Case reports provide a valuable learning resource for the scientific community and can indicate areas of interest for future research. They should not be used in isolation to guide treatment choices or public health policy.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.