Objectives: Oestrogen deficiency is a rare disease and leads inter alia to arthralgia and osteoporosis in men. The clinical relevance of aromatase to a functioning male metabolism has become evident since 1991, when cases of patients with oestrogen deficiency caused by aromatase mutation were first described. Only few cases are known so far, which will now be presented in a case report and review of the literature.
Methods: All available publications since the first description in 1991 dealing with loss-of-function aromatase mutation in men were summarised and our case report was added.
Results: The mutations that cause the aromatase protein to lose function leads to a rather heterogeneous clinical picture. It is, however, clear that oestrogens play a central role in male patients, especially in bone metabolism. Most frequently, tall stature, unclosed epiphyseal joints, and osteoporosis are detected in affected individuals as a consequence of the change in hormonal status.
Conclusions: As low oestrogen is associated with arthralgia, patients with aromatase mutation may be referred to a rheumatologist. Despite aromatase deficiency being a rare disease, the study of the effects of oestrogen on male bone development provides important insights for endocrine bone regulation. It has been demonstrated that androgens alone are not sufficient for adequate skeletal development in males. The described effects of loss of oestrogens are known from the aromatase inhibitor therapy in breast cancer treatment. This work highlights the important role of oestrogens in individual health and disease in men. Molecular effects of oestrogens on bone metabolism are summarised.