ORIGINAL ARTICLE Overview of Gynecomastia in the Modern Era and the Leeds Gynaecomastia Investigation Algorithm Samir Rahmani, MB.ChB, MRCS, Diploma & MSc General Surgery,* Philip Turton, FRCSEd FRCS(genSURG) MD(Hons),* Abeer Shaaban, MBBCh, PhD, FRCPath, Dip Health Resources,   and Barbara Dall, MBBCh, MD, FRCRad à *Department of Breast & Reconstructive Surgery, The Leeds Teaching Hospitals Trust, Leeds, United Kingdom;   Department of Pathology, The Leeds Teaching Hospitals Trust, Leeds, United Kingdom; and à Department of Radiology, The Leeds Teaching Hospitals Trust, Leeds, United Kingdom n Abstract: Gynecomastia is a benign enlargement of male breast glandular tissue. At least a third of males are affected at some time during their lifetime. Idiopathic causes exceed other etiologies and relate to an imbalance in the ratio of estrogen to androgen tissue levels or end-organ responsiveness to these hormones. Assessment must include a thor- ough history and clinical examination, specific blood investigations and usually tissue sampling and ⁄ or breast imaging. Man- agement consists of a combination of measures that may include simple reassurance, pharmacological manipulation, medical treatment or surgery. Hormone therapy may help to abort the acute proliferative phase of gynecomastia with a 30% response rate but should not be considered in chronic established cases. Surgical treatment may comprise simple liposuction for a predominant fatty component or direct excision when glandular tissue is predominant. The main aim is to control the patient’s symptoms and to exclude other etiological factors. n Key Words: breast tissue sampling and imaging, gynecomastia, investigation algorithm, management, surgery G ynecomastia is a common clinical condition in men consisting of a benign progressive enlarge- ment or proliferation of male breast glandular tissue. It often presents as a diffuse or a discrete retro-areola lump. It may be an incidental finding on routine examina- tion. More commonly it presents as an acute, unilateral or bilateral, tender swelling beneath the areola region. The vast majority of cases of gynecomastia are consid- ered to be idiopathic. However, in some patients, for teenagers and young men in particular it may lead to significant embarrassment and social impediments lead- ing to decreased participation in physical activities, social activities, and even formation of relationships. It is critical to recognize those patients who may have an underlying pathological condition or who do not have gynecomastia but other causes for a male breast lump. If the gynecomastia is not idiopathic, referral to a specialist is often warranted. This can be achieved in the majority of cases by taking a thorough history, performing a comprehensive clinical examina- tion and checking a few screening laboratory tests where indicated. In this era of increasing levels of obesity, primary and secondary care is seeing increasing numbers of patients with pseudogynecomastia. For these cases only simple reassurance coupled with advice on diet- ing and exercise may be needed (1,2). In a number of cases psychological counseling, medical intervention and ⁄ or surgical intervention may be required (3). When referral to secondary care occurs, teenagers will usually be reviewed initially by a pediatric endo- crinologist, although adults are commonly seen by specialist breast surgeons. PREVALENCE Depending on the criteria used for diagnosis, gynecomastia or excessive male breast development may have prevalence between 32% and 65% of the Address correspondence and reprint requests to: Samir Rahmani, MB.ChB, MRCS, Diploma & Msc General Surgery, Clinical Research Fellow in General Surgery, Breast and Reconstructive Surgery, Leeds General Infir- mary, Leeds Teaching Hospitals, Great George Street, Leeds, LS1 3EX, UK, or e-mail: rahmanisamir@hotmail.com. DOI: 10.1111/j.1524-4741.2011.01080.x Ó 2011 Wiley Periodicals, Inc., 1075-122X/11 The Breast Journal, Volume 17 Number 3, 2011 246–255