[45,X/46,XY/47,XXY chromosome mosaicism as a cause of hypergonadotropic hypogonadism diagnosed in late middle age].

UNLABELLED

HISTORY AND FINDINGS ON EXAMINATION: A 62-year-old man complaining of increasingly painful swelling in both breasts over the previous 6 months was admitted to hospital because an endocrine tumour or paraneoplasia was suspected. Unmarried and childless he had always been well except for mild diabetes treated with glibenclamide. On examination both breasts were enlarged with easily palpable glandular tissue; the testes were small and atrophic. Hair growth and distribution were normal.

LABORATORY TESTS

Serum testosterone concentration was low (1.3 ng/ml), while luteinizing and follicle-stimulating hormones (27.3 mU/ml and 95 mU/ml, respectively) were raised. Chromosome analysis revealed 45,X/46,XY/47,XYY mosaicism without evidence of structural aberrations. Mammography showed true gynecomastia without signs of malignancy.

TREATMENT AND COURSE

Hypergonadotrophic hypogonadism having been diagnosed the patient was given substitution treatment with 250 mg testosterone, 250 mg i.m. every 3 weeks. The concentrations of luteinizing and follicle-stimulating hormones became normal and the gynecomastia regressed over the subsequent 6 months.

CONCLUSION

Mosaicism of the sex chromosomes should be considered in the differential diagnosis of late-onset hypogonadism, even in phenotypically unremarkable men.