LAUSR

Background Gynaecomastia is a fairly common condition in puberty but is rare in prepubertal boys. While it is necessary to exclude possible endocrinopathay in prepubertal gynaecomastia, medication is an important and potentially reversible cause to consider in new onset gynaecomastia. Isoniazid-induced gynaecomastia has been reported in adult males, but none was reported in the paediatric population and general paediatricians may not be aware of this uncommon side effect. Case presentation We hereby report a 11-year-old prepubertal boy who developed gynaecomastia while taking anti-tuberculosis drugs. Investigations excluded endocrinopathies. Gynaecomastia subsided 8 weeks after stopping isoniazid. Conclusion This case is the first paediatric case report describing the association of gynaecomastia with isoniazid use. It is important for general paediatricians to recognize this entity, as prompt diagnosis and cessation of the offending drug can lead to resolution of the problem.