madman
Super Moderator
Abstract
Breast tissue undergoes a series of changes from birth to puberty. The majority of the changes are transient, and related to physiological hormonal changes. Although the breast is identical in both sexes at birth, its histology and development will eventually differ. It is important for radiologists to have a basic understanding of endocrinological changes and appearance on imaging to avoid potential pitfalls, particularly on ultrasound, which is the primary modality used to evaluate the breast.
Introduction
Boys and girls undergo endocrinological changes that influence normal breast development until puberty. In some children, these hormonal changes can lead to an unusual but transient appearance, potentially becoming a source of anxiety to patients and their parents and a source of confusion to clinicians and radiologists. From birth to puberty, pathological conditions of the breast are mostly benign and very often a transient part of normal development. Furthermore, malignant breast lesions, especially the adult-type primary breast carcinoma, in the pediatric population are exceedingly rare [1–3]. Most breast changes in the pediatric population can be diagnosed clinically, but sometimes imaging evaluation is recommended. Ultrasound (US) is the imaging modality of choice to evaluate the breast in pediatrics [4, 5]. Thus, familiarity with these transient changes and the occasional pathological conditions is important in order to avoid unnecessary and costly work-ups and to prevent stress and anxiety for patients and parents.
In this article, we focus on some basic but key endocrinological principles, normal physiological changes of the pediatric breast and its variants, and common pathologies of breast development throughout childhood and adolescence. We also describe the US appearance of the normal breast in childhood and adolescence, physiological variations, and certain pathological conditions that occur during this period. As the focus of this article is the spectrum of breast development throughout childhood, breast neoplasms are not discussed.
*Imaging of the breast in the pediatric population
*Breast development in utero
*Breast changes in the newborn period
*Neonatal breast enlargement
*Neonatal mastitis (mastitis neonatorum)
*Breast changes in infancy and the concept of mini-puberty of infancy
*Infantile mammary duct ectasia
*Breast changes in the prepubertal child (toddler and early childhood)
-Gynecomastia in the prepubertal boy
-Isolated premature thelarche and central precocious puberty in girls
*Breast changes during puberty
Breast changes in boys during puberty
At the beginning of puberty in boys, levels of estrogen increase transiently, stimulating the growth of breast tissue; however, this is quickly followed by a surge in testosterone, antagonizing the estrogen effect. The lack of a progesterone surge in boys precludes the development of terminal lobular units. This means that there is a temporary proliferation of breast ducts and stroma followed by their rapid involution. Cooper ligaments are also absent in boys, whereas pectoralis muscles are more prominent than in girls. The sonographic appearance of the normal pubertal breast in boys is no different from its prepubertal appearance with visualization of subcutaneous fat and a faint nipple shadow [38–40]
Gynecomastia in the adolescent boy
Gynecomastia is defined as the development of mammary glandular tissue in the male, more precisely ductal and stromal tissue proliferation, due to an imbalance of the testosterone/ estrogen ratio [38, 41]. Gynecomastia is commonly seen during early and mid-puberty, with a reported incidence of 30% to 60% at this age [41].
Gynecomastia can be unilateral or bilateral, symmetrical or asymmetrical, and synchronous or metachronous. Laboratory testing usually fails to reveal abnormal circulating estrogen and/or androgen levels. Most cases of physiological gynecomastia resolve spontaneously as androgen levels continue to rise later in puberty, lasting no longer than 2 years [42, 43]. Upon physical examination, a subareolar, palpable, mobile lump, sometimes tender, is palpated. Occasionally, US is requested to rule out a mass or to differentiate it from pseudogynecomastia or lipomastia, which is the focal accumulation of adipose tissue, usually in overweight adolescents, that is always bilateral [40, 44]. Three patterns of gynecomastia have been described on US imaging: 1) a nodular pattern occurring in the early phase, seen as a hypoechoic disc-shaped mass beneath the nipple surrounded by fatty tissue (Fig. 5); 2) a dendritic pattern during the chronic phase, seen as a flame shape of hypoechogenicity in the retroareolar region with irregular margins that infiltrate the adjacent subcutaneous fat (Fig. 6); and 3) a diffuse pattern, seen on sonography, identical to the female dense heterogeneous breast [4, 38, 44, 45]. In US, lipomastia is seen as diffuse adipose tissue proliferation without fibroglandular tissue. No discrete mass should be present and, different from gynecomastia, no distinct borders are identified (Fig. 7) [40]. Treatment is not necessary in most cases because physiological pubertal gynecomastia resolves spontaneously. However, when gynecomastia is severe and persistent, pharmacological treatment or surgery might be indicated [46].
Pathological gynecomastia is rare in pediatric patients and young adults, and it is secondary to elevated levels of exogenous or endogenous estrogens or to low production of testosterone [46]. The age of appearance and progression of gynecomastia is very important, with adolescents with late-onset gynecomastia deserving a more detailed evaluation. A thorough clinical history, including the age of pubertal development, exposure to hormones, medications with antiandrogenic actions, consumption of marijuana, and family history of gynecomastia, should be explored (Table 1) [47]. US evaluation of the testicles is indicated when testicular asymmetry is found or a mass is palpated upon physical examination. If suspected, especially when FSH levels are elevated, a karyotype should be ordered to exclude Klinefelter syndrome.
*Breast changes in girls during puberty
*Asymmetrical breast development during puberty
*Mammary ductal ectasia in the pubertal girl
*Juvenile breast hypertrophy
*Fibrocystic changes
Conclusion
The breast has an identical histological composition in both sexes until puberty when it differentiates. Until puberty, the breast in both boys and girls undergoes transient changes triggered by physiological hormonal changes. It is important to be familiar with some basic endocrinological principles, such as perinatal hormonal changes and the so-called mini-puberty of infancy in early childhood, as well as with hormonal changes during puberty that can affect the clinical and imaging appearance of the developing breast in both sexes. In the pediatric population, US is the imaging modality of choice to evaluate the breast. Physiological changes of the developing breast can be unilateral, affect both sexes, and can simulate pathology causing parental anxiety that could lead to unnecessary workup. Furthermore, because primary breast malignancies are very rare in this population and invasive procedures can cause the arrest of the breast bud development, any possible breast intervention should be carefully scrutinized.
Breast tissue undergoes a series of changes from birth to puberty. The majority of the changes are transient, and related to physiological hormonal changes. Although the breast is identical in both sexes at birth, its histology and development will eventually differ. It is important for radiologists to have a basic understanding of endocrinological changes and appearance on imaging to avoid potential pitfalls, particularly on ultrasound, which is the primary modality used to evaluate the breast.
Introduction
Boys and girls undergo endocrinological changes that influence normal breast development until puberty. In some children, these hormonal changes can lead to an unusual but transient appearance, potentially becoming a source of anxiety to patients and their parents and a source of confusion to clinicians and radiologists. From birth to puberty, pathological conditions of the breast are mostly benign and very often a transient part of normal development. Furthermore, malignant breast lesions, especially the adult-type primary breast carcinoma, in the pediatric population are exceedingly rare [1–3]. Most breast changes in the pediatric population can be diagnosed clinically, but sometimes imaging evaluation is recommended. Ultrasound (US) is the imaging modality of choice to evaluate the breast in pediatrics [4, 5]. Thus, familiarity with these transient changes and the occasional pathological conditions is important in order to avoid unnecessary and costly work-ups and to prevent stress and anxiety for patients and parents.
In this article, we focus on some basic but key endocrinological principles, normal physiological changes of the pediatric breast and its variants, and common pathologies of breast development throughout childhood and adolescence. We also describe the US appearance of the normal breast in childhood and adolescence, physiological variations, and certain pathological conditions that occur during this period. As the focus of this article is the spectrum of breast development throughout childhood, breast neoplasms are not discussed.
*Imaging of the breast in the pediatric population
*Breast development in utero
*Breast changes in the newborn period
*Neonatal breast enlargement
*Neonatal mastitis (mastitis neonatorum)
*Breast changes in infancy and the concept of mini-puberty of infancy
*Infantile mammary duct ectasia
*Breast changes in the prepubertal child (toddler and early childhood)
-Gynecomastia in the prepubertal boy
-Isolated premature thelarche and central precocious puberty in girls
*Breast changes during puberty
Breast changes in boys during puberty
At the beginning of puberty in boys, levels of estrogen increase transiently, stimulating the growth of breast tissue; however, this is quickly followed by a surge in testosterone, antagonizing the estrogen effect. The lack of a progesterone surge in boys precludes the development of terminal lobular units. This means that there is a temporary proliferation of breast ducts and stroma followed by their rapid involution. Cooper ligaments are also absent in boys, whereas pectoralis muscles are more prominent than in girls. The sonographic appearance of the normal pubertal breast in boys is no different from its prepubertal appearance with visualization of subcutaneous fat and a faint nipple shadow [38–40]
Gynecomastia in the adolescent boy
Gynecomastia is defined as the development of mammary glandular tissue in the male, more precisely ductal and stromal tissue proliferation, due to an imbalance of the testosterone/ estrogen ratio [38, 41]. Gynecomastia is commonly seen during early and mid-puberty, with a reported incidence of 30% to 60% at this age [41].
Gynecomastia can be unilateral or bilateral, symmetrical or asymmetrical, and synchronous or metachronous. Laboratory testing usually fails to reveal abnormal circulating estrogen and/or androgen levels. Most cases of physiological gynecomastia resolve spontaneously as androgen levels continue to rise later in puberty, lasting no longer than 2 years [42, 43]. Upon physical examination, a subareolar, palpable, mobile lump, sometimes tender, is palpated. Occasionally, US is requested to rule out a mass or to differentiate it from pseudogynecomastia or lipomastia, which is the focal accumulation of adipose tissue, usually in overweight adolescents, that is always bilateral [40, 44]. Three patterns of gynecomastia have been described on US imaging: 1) a nodular pattern occurring in the early phase, seen as a hypoechoic disc-shaped mass beneath the nipple surrounded by fatty tissue (Fig. 5); 2) a dendritic pattern during the chronic phase, seen as a flame shape of hypoechogenicity in the retroareolar region with irregular margins that infiltrate the adjacent subcutaneous fat (Fig. 6); and 3) a diffuse pattern, seen on sonography, identical to the female dense heterogeneous breast [4, 38, 44, 45]. In US, lipomastia is seen as diffuse adipose tissue proliferation without fibroglandular tissue. No discrete mass should be present and, different from gynecomastia, no distinct borders are identified (Fig. 7) [40]. Treatment is not necessary in most cases because physiological pubertal gynecomastia resolves spontaneously. However, when gynecomastia is severe and persistent, pharmacological treatment or surgery might be indicated [46].
Pathological gynecomastia is rare in pediatric patients and young adults, and it is secondary to elevated levels of exogenous or endogenous estrogens or to low production of testosterone [46]. The age of appearance and progression of gynecomastia is very important, with adolescents with late-onset gynecomastia deserving a more detailed evaluation. A thorough clinical history, including the age of pubertal development, exposure to hormones, medications with antiandrogenic actions, consumption of marijuana, and family history of gynecomastia, should be explored (Table 1) [47]. US evaluation of the testicles is indicated when testicular asymmetry is found or a mass is palpated upon physical examination. If suspected, especially when FSH levels are elevated, a karyotype should be ordered to exclude Klinefelter syndrome.
*Breast changes in girls during puberty
*Asymmetrical breast development during puberty
*Mammary ductal ectasia in the pubertal girl
*Juvenile breast hypertrophy
*Fibrocystic changes
Conclusion
The breast has an identical histological composition in both sexes until puberty when it differentiates. Until puberty, the breast in both boys and girls undergoes transient changes triggered by physiological hormonal changes. It is important to be familiar with some basic endocrinological principles, such as perinatal hormonal changes and the so-called mini-puberty of infancy in early childhood, as well as with hormonal changes during puberty that can affect the clinical and imaging appearance of the developing breast in both sexes. In the pediatric population, US is the imaging modality of choice to evaluate the breast. Physiological changes of the developing breast can be unilateral, affect both sexes, and can simulate pathology causing parental anxiety that could lead to unnecessary workup. Furthermore, because primary breast malignancies are very rare in this population and invasive procedures can cause the arrest of the breast bud development, any possible breast intervention should be carefully scrutinized.
