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doi:10.1111/jpc.12744
INSTRUCTIVE CASE
Intermittent midline suprasternal neck mass caused by superior herniation of the thymus Siew Choo Su,1,2 Thomas Hess,3 Annie Whybourne4 and Anne B Chang1,5 1
Queensland Children’s Respiratory Centre, Queensland Children’s Medical Research Institute, 3Department of Radiology, Royal Children’s Hospital, Brisbane, Queensland, 4Department of Maternal and Child Health, Royal Darwin Hospital, 5Child Health Division, Menzies School of Health Research, Charles Darwin University, Darwin, Northern Territory, Australia and 2Department of Paediatrics, Hospital Kuala Lumpur, Kuala Lumpur, Malaysia
Abstract: Neck masses in infants and children have a wide differential diagnosis. However, neck masses apparent only during raised intrathoracic pressure are rare with a limited number of causes, including superior herniation of the normal thymus, apical lung herniation, jugular phlebectasia and laryngocoele. These conditions can easily be differentiated from one another by imaging. We present an infant with intermittent suprasternal neck mass visible only during increased intrathoracic pressure, produced either by crying or straining. Diagnosis of superior herniation of the thymus into the neck was confirmed by ultrasonography with the characteristic sonographic appearances of the normal thymus as well as its shape, size and location. Ultrasonography should be the first imaging modality of choice. Management of superior herniation of the thymus into the neck should be conservative as the thymus naturally involutes with increasing age. Awareness of the differential diagnosis of neck swelling present only on Vasalva manoeuvre or increased intrathoracic pressure is important to prevent unnecessary tests, avoid radiation, biopsy and surgery. Key words:
infant; neck mass; thymus.
Case Report A 7-month-old boy presented with a 3-month history of intermittent large midline suprasternal neck swelling (Fig. 1), which was visible only upon straining, particularly when he cried or arched his back. There was no associated cough, wheeze, dysphonia or dysphagia. He had intermittent stridor and mild dyspnoea with chest recessions since he was 3 months old, which were unrelated to the appearance or disappearance of the neck swelling. He was born via elective Caesarean section at 38 weeks gestation (birthweight 3.2 kg) following a normal pregnancy and had no respiratory difficulty at birth. He had bilateral congenital talipes equinovarus and underwent bilateral Achilles
Key Points 1 Midline anterior neck masses apparent only during increased intrathoracic pressure are rare with a limited differential diagnosis. 2 Ultrasonography is recommended as the first imaging modality of choice. 3 Prompt diagnosis is essential to avoid unnecessary radiation, biopsy or surgery. Correspondence: Dr Siew Choo Su, Department of Respiratory Medicine, Royal Children’s Hospital, Level 5, Woolworths Building, Herston Road, Herston, Qld. 4029, Australia. Fax: 07 3636 5578; email: siewchoo_su@ yahoo.com Conflict of interest: None. Accepted for publication 24 August 2014.
344
Fig. 1 Clinical photograph shows the appearance of the neck at rest (left) and presence of a midline suprasternal neck mass during straining (right).
tenotomy at 3 months old. He was the youngest of two children in the family, with no significant family history. Physical examination revealed a diffuse, non-tender, triangular-shaped, non-compressible mass protruding above the suprasternal notch that was apparent only upon straining. The inferior border of the mass was not palpable. There was no murmur, thrill or crepitus noted over the mass. The mass was not palpable during normal tidal breathing. He had intermittent increased work of breathing with a cogwheel stridor. Complete clinical examination was otherwise unremarkable. Chest radiograph was normal. Flexible bronchoscopy revealed mild laryngomalacia with normal vocal cord function. Ultrasonographic examination of the neck revealed a wellcircumscribed, hypoechoic mass with multiple echogenic foci and linear structures protruding superiorly in the midline of the
Journal of Paediatrics and Child Health 51 (2015) 344–346 © 2014 The Authors Journal of Paediatrics and Child Health © 2014 Paediatrics and Child Health Division (Royal Australasian College of Physicians).
SC Su et al.
Midline suprasternal neck mass
Fig. 2 Grayscale sonogram of lower anterior neck at rest (left) and presence of a wellcircumscribed hypoechoic mass with multiple echogenic foci and linear structures during straining (right).
neck anterior to the cervical trachea during raised intrathoracic pressure, which was consistent with normal thymus (Fig. 2). The mass descended back into the upper mediastinum when the child stopped straining. The adjacent thyroid gland, common carotid arteries and internal jugular veins were normal.
Discussion We present an infant with intermittent neck swelling caused by intermittent superior herniation of the normal thymus into the neck. Reports of thymic herniation causing a neck mass visible only during increased intrathoracic pressure produced by straining, crying or performing Valsalva manoeuvre are rare, with only four published cases.1–3 The importance of our report is the consideration of the differential diagnosis and appropriate investigations to minimise unnecessary tests. The diagnosis was made by ultrasound in this child by the presence of characteristic sonographic appearances of the normal thymus as well as its shape, size and location. Although some have advocated magnetic resonance imaging (MRI)1 or computerised tomography,2 our report illustrates that simple ultrasonography suffices as the imaging modality when the thymus has characteristic sonographic4 appearances. Three of the published cases were described in asymptomatic older children (aged 7–8 years) who underwent complex imaging with either MRI or computed tomography.1,2 The sole other report in an infant, managed by respiratory physicians, did not undergo complex imaging, but airway fluoroscopy (with consequent unnecessary radiation) was undertaken.3 As our patient had an inspiratory stridor, we undertook a flexible bronchoscopy, revealing laryngomalacia and absence of tracheal compression. The stridor in our patient was caused by the incidental laryngomalacia (rather than a result of herniation of the thymus), from the characteristic intermittent cogwheel stridor and bronchoscopic appearance. Although herniation of the thymus into the neck during forced exhalation causing posterior buckling of the cervicothoracic trachea may cause stridor, the absence of tracheal compression makes this situation highly unlikely in our patient. In children without stridor, bronchoscopy would not have been necessary. The postulated mechanism of herniation of the thymus is that the connective tissue normally limiting thymic movement is exceptionally loose, enabling the thymus to herniate superiorly into the neck.1 As thymus attains its largest relative size at 3 years of age and reaches its largest weight at puberty before involuting in adulthood,5 management should be conservative.
The thymus develops from the ventral saccules of the 3rd–4th pharyngeal pouches during the 6–10th gestational weeks. Each thymic primordium elongates caudally and medially and begins to fuse in the midline by the 8th week before descending to its characteristic position in the anterior mediastinum, between the sternum, parietal pericardium and thoracic inlet.5 Ectopic thymus can be found anywhere along the pathway of descent, from the angle of mandible to the mediastinum, presenting as a neck mass palpable at all times during the first few years of life. The differential diagnosis of a midline anterior neck mass is wide, requiring surgery and/or biopsy in some. These differential diagnosis (ectopic thymus, thyroglossal duct cyst, cystic hygroma, benign and malignant tumours) were excluded in our case as the mass appeared only on straining, which may be caused by only a handful of other conditions including apical lung herniation, jugular phlebectasia and laryngocoele, which can easily be differentiated from one another on imaging.1 Congenital lung herniation is the protrusion of the lung apex into the cervical region due to partial absence or laxity of Sibson’s fascia, or increased space between the scalenus anterior and sternocleidomastoid muscles.6 Unilateral or bilateral congenital lung herniation manifests in the first year of life as compressible supraclavicular or suprasternal neck mass with crepitus during raised intrathoracic pressure. It rarely causes chronic cough, hoarseness or stridor from external compression of the trachea or transient impairment of jugular venous drainage.6 As it tends to resolve spontaneously, surgery is only warranted if there is incarceration of the lung apex or significant compression of nearby structures. Jugular phlebectasia, a congenital fusiform dilatation of the jugular vein usually affecting the right internal jugular vein,7 presents as a compressible lateral neck swelling rather than a midline mass during the Valsalva manoeuvre. Diagnosis is made from ultrasonography with colour Doppler flow imaging, which identifies local dilatation of the affected vein on Valsalva’s manoeuvre.7 Management is conservative unless complications such as thrombosis, Horner’s syndrome or cosmetically disfiguring lesions occur. Laryngocoele (internal, external or mixed type) is an abnormally dilated laryngeal saccule arising between the laryngeal ventricular folds. External laryngocoele herniates through the thyrohyoid membrane, presenting as a neck swelling with the Valsalva manoeuvre.8 It can occur in children but typically affects men in their 50s to 60s.3 Although most are asymptomatic, some can present with acute deterioration of stridor and dyspnoea requiring emergency tracheostomy. MRI is
Journal of Paediatrics and Child Health 51 (2015) 344–346 © 2014 The Authors Journal of Paediatrics and Child Health © 2014 Paediatrics and Child Health Division (Royal Australasian College of Physicians)
345
Midline suprasternal neck mass
SC Su et al.
recommended as laryngocoeles are associated with laryngeal carcinomas.8 In our patient, the diagnosis of superior herniation of the thymus into the neck was confirmed by the characteristic sonographic features of a normal thymus visualised only during increased intrathoracic pressure. The absence of air visualised in the neck mass excluded laryngocoele and lung herniation, and phlebectasia was excluded as the mass was not compressible. We did not proceed with further imaging as the diagnosis was firmly made with the well-described sonographic features, and flexible bronchoscopy did not reveal any tracheal compromise. In summary, neck masses apparent only during increased intrathoracic pressure are rare with a limited differential diagnosis. Ultrasonography should be the first imaging modality of choice. Clinicians are alerted to this condition as it looks alarming, yet simple and prompt diagnosis using minimal investigations avoids unnecessary radiation, biopsy or surgery.
Acknowledgement AC is supported by a NHMRC practitioner fellowship (grant 1058213).
References 1 Wong KT, Lee DLY, Chan MSM, Tsang RKY, Yuen EHY, Ahuja AT. Unusual anterior neck mass visible only during Valsalva’s maneuver in a child. AJR 2005; 185: 1355–7. 2 Senel S, Erkek N, Otgun I, Cinar G, Cifci A, Yoney A. Superior herniation of the thymus into the neck – a familial pattern. J. Thorac. Imaging 2008; 23: 131–4. 3 McDougall CM, Culham G, Seear MD, Chilvers MA. Superior herniation of the mediastinum presenting as an anterior neck mass on straining. Pediatr. Pulmonol. 2012; 47: 710–12. 4 Han BK, Babcock DS, Oestreich AE. Normal thymus in infancy: sonographic characteristics. Radiology 1989; 170: 471–4. 5 Tovi F, Mares AJ. The aberrant cervical thymus. Embryology, pathology, and clinical implications. Am. J. Surg. 1978; 136: 631–7. 6 Mehdi NF, Weinberger M, Abu-Hasan MN. Radiological case of the month. Bilateral congenital apical lung herniation. Arch. Pediatr. Adolesc. Med. 2002; 156: 81–2. 7 Hu X, Li J, Hu T, Jiang X. Congenital jugular vein phlebectasia. Am. J. Otolaryngol. 2005; 26: 172–4. 8 Woo EK, Connor SEJ. CT and MRI appearances of cystic lesions in the suprahyoid neck: a pictorial review. Dentomaxillofacial. Radiol. 2007; 36: 1–9.
Questions 1 The differential diagnosis for an intermittent midline anterior neck mass palpable only during increased intrathoracic pressure includes the below, except: a Laryngocoele b Ectopic thymus c Right internal jugular phlebectasia d Unilateral apical lung herniation e Left external jugular phlebectasia
346
The differential diagnosis of an intermittent neck mass palpable only during raised intrathoracic pressure includes superior herniation of the normal thymus into the neck, laryngocoele, jugular phlebectasia (usually affecting the right internal jugular vein but can also involve the left as well as the external jugular veins) and apical lung herniation (can be unilateral or bilateral). Ectopic thymus produces a neck mass that is palpable all the time, and not palpable only during raised intrathoracic pressure. Answer is (b). 2 The development of the thymus begins in the 6–10th week of gestation and it continues to grow after birth. Which of the following is true? a The thymus reaches its largest weight in adulthood b The largest relative size of the thymus is during puberty c The largest relative size of the thymus is at around 3 years of age d The largest weight of the thymus is at around 3 years of age e The thymus involutes by around 3 years of age The thymus reaches its largest relative size at around 3 years of age, attains its largest weight at puberty and involutes in adulthood. Answer is (c). 3 Neck masses in infants and children are rare and may be alarming to both parents and clinicians. Which of the following statements regarding investigations of neck masses in infants and children is true? a Magnetic resonance imaging should always be the first imaging modality of choice b Superior herniation of the normal thymus into the neck can be diagnosed with ultrasonography with its characteristic appearance c Magnetic resonance imaging is recommended in jugular phlebectasia as it is associated with malignancy d Flexible bronchoscopy should be performed in all asymptomatic infants and children with neck masses e All of the above Magnetic resonance imaging is one of the imaging modalities for investigation of neck masses; however, it does not necessarily have to be the first imaging modality of choice as certain benign conditions can be easily diagnosed with ultrasonography, which is widely available and can be done without general anaesthesia. Conditions such as herniation of the normal thymus into the neck can be diagnosed on ultrasonography as the thymus has characteristic sonographic appearances (well-circumscribed, hypoechoic mass with multiple echogenic foci and linear structures). Magnetic resonance imaging is recommended in cases of laryngocoeles as they are associated with laryngeal carcinomas. In asymptomatic children without stridor or respiratory distress, flexible bronchoscopy is not necessary. Answer is (b).
Journal of Paediatrics and Child Health 51 (2015) 344–346 © 2014 The Authors Journal of Paediatrics and Child Health © 2014 Paediatrics and Child Health Division (Royal Australasian College of Physicians)
Copyright of Journal of Paediatrics & Child Health is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use.
doi:10.1111/jpc.12744
INSTRUCTIVE CASE
Intermittent midline suprasternal neck mass caused by superior herniation of the thymus Siew Choo Su,1,2 Thomas Hess,3 Annie Whybourne4 and Anne B Chang1,5 1
Queensland Children’s Respiratory Centre, Queensland Children’s Medical Research Institute, 3Department of Radiology, Royal Children’s Hospital, Brisbane, Queensland, 4Department of Maternal and Child Health, Royal Darwin Hospital, 5Child Health Division, Menzies School of Health Research, Charles Darwin University, Darwin, Northern Territory, Australia and 2Department of Paediatrics, Hospital Kuala Lumpur, Kuala Lumpur, Malaysia
Abstract: Neck masses in infants and children have a wide differential diagnosis. However, neck masses apparent only during raised intrathoracic pressure are rare with a limited number of causes, including superior herniation of the normal thymus, apical lung herniation, jugular phlebectasia and laryngocoele. These conditions can easily be differentiated from one another by imaging. We present an infant with intermittent suprasternal neck mass visible only during increased intrathoracic pressure, produced either by crying or straining. Diagnosis of superior herniation of the thymus into the neck was confirmed by ultrasonography with the characteristic sonographic appearances of the normal thymus as well as its shape, size and location. Ultrasonography should be the first imaging modality of choice. Management of superior herniation of the thymus into the neck should be conservative as the thymus naturally involutes with increasing age. Awareness of the differential diagnosis of neck swelling present only on Vasalva manoeuvre or increased intrathoracic pressure is important to prevent unnecessary tests, avoid radiation, biopsy and surgery. Key words:
infant; neck mass; thymus.
Case Report A 7-month-old boy presented with a 3-month history of intermittent large midline suprasternal neck swelling (Fig. 1), which was visible only upon straining, particularly when he cried or arched his back. There was no associated cough, wheeze, dysphonia or dysphagia. He had intermittent stridor and mild dyspnoea with chest recessions since he was 3 months old, which were unrelated to the appearance or disappearance of the neck swelling. He was born via elective Caesarean section at 38 weeks gestation (birthweight 3.2 kg) following a normal pregnancy and had no respiratory difficulty at birth. He had bilateral congenital talipes equinovarus and underwent bilateral Achilles
Key Points 1 Midline anterior neck masses apparent only during increased intrathoracic pressure are rare with a limited differential diagnosis. 2 Ultrasonography is recommended as the first imaging modality of choice. 3 Prompt diagnosis is essential to avoid unnecessary radiation, biopsy or surgery. Correspondence: Dr Siew Choo Su, Department of Respiratory Medicine, Royal Children’s Hospital, Level 5, Woolworths Building, Herston Road, Herston, Qld. 4029, Australia. Fax: 07 3636 5578; email: siewchoo_su@ yahoo.com Conflict of interest: None. Accepted for publication 24 August 2014.
344
Fig. 1 Clinical photograph shows the appearance of the neck at rest (left) and presence of a midline suprasternal neck mass during straining (right).
tenotomy at 3 months old. He was the youngest of two children in the family, with no significant family history. Physical examination revealed a diffuse, non-tender, triangular-shaped, non-compressible mass protruding above the suprasternal notch that was apparent only upon straining. The inferior border of the mass was not palpable. There was no murmur, thrill or crepitus noted over the mass. The mass was not palpable during normal tidal breathing. He had intermittent increased work of breathing with a cogwheel stridor. Complete clinical examination was otherwise unremarkable. Chest radiograph was normal. Flexible bronchoscopy revealed mild laryngomalacia with normal vocal cord function. Ultrasonographic examination of the neck revealed a wellcircumscribed, hypoechoic mass with multiple echogenic foci and linear structures protruding superiorly in the midline of the
Journal of Paediatrics and Child Health 51 (2015) 344–346 © 2014 The Authors Journal of Paediatrics and Child Health © 2014 Paediatrics and Child Health Division (Royal Australasian College of Physicians).
SC Su et al.
Midline suprasternal neck mass
Fig. 2 Grayscale sonogram of lower anterior neck at rest (left) and presence of a wellcircumscribed hypoechoic mass with multiple echogenic foci and linear structures during straining (right).
neck anterior to the cervical trachea during raised intrathoracic pressure, which was consistent with normal thymus (Fig. 2). The mass descended back into the upper mediastinum when the child stopped straining. The adjacent thyroid gland, common carotid arteries and internal jugular veins were normal.
Discussion We present an infant with intermittent neck swelling caused by intermittent superior herniation of the normal thymus into the neck. Reports of thymic herniation causing a neck mass visible only during increased intrathoracic pressure produced by straining, crying or performing Valsalva manoeuvre are rare, with only four published cases.1–3 The importance of our report is the consideration of the differential diagnosis and appropriate investigations to minimise unnecessary tests. The diagnosis was made by ultrasound in this child by the presence of characteristic sonographic appearances of the normal thymus as well as its shape, size and location. Although some have advocated magnetic resonance imaging (MRI)1 or computerised tomography,2 our report illustrates that simple ultrasonography suffices as the imaging modality when the thymus has characteristic sonographic4 appearances. Three of the published cases were described in asymptomatic older children (aged 7–8 years) who underwent complex imaging with either MRI or computed tomography.1,2 The sole other report in an infant, managed by respiratory physicians, did not undergo complex imaging, but airway fluoroscopy (with consequent unnecessary radiation) was undertaken.3 As our patient had an inspiratory stridor, we undertook a flexible bronchoscopy, revealing laryngomalacia and absence of tracheal compression. The stridor in our patient was caused by the incidental laryngomalacia (rather than a result of herniation of the thymus), from the characteristic intermittent cogwheel stridor and bronchoscopic appearance. Although herniation of the thymus into the neck during forced exhalation causing posterior buckling of the cervicothoracic trachea may cause stridor, the absence of tracheal compression makes this situation highly unlikely in our patient. In children without stridor, bronchoscopy would not have been necessary. The postulated mechanism of herniation of the thymus is that the connective tissue normally limiting thymic movement is exceptionally loose, enabling the thymus to herniate superiorly into the neck.1 As thymus attains its largest relative size at 3 years of age and reaches its largest weight at puberty before involuting in adulthood,5 management should be conservative.
The thymus develops from the ventral saccules of the 3rd–4th pharyngeal pouches during the 6–10th gestational weeks. Each thymic primordium elongates caudally and medially and begins to fuse in the midline by the 8th week before descending to its characteristic position in the anterior mediastinum, between the sternum, parietal pericardium and thoracic inlet.5 Ectopic thymus can be found anywhere along the pathway of descent, from the angle of mandible to the mediastinum, presenting as a neck mass palpable at all times during the first few years of life. The differential diagnosis of a midline anterior neck mass is wide, requiring surgery and/or biopsy in some. These differential diagnosis (ectopic thymus, thyroglossal duct cyst, cystic hygroma, benign and malignant tumours) were excluded in our case as the mass appeared only on straining, which may be caused by only a handful of other conditions including apical lung herniation, jugular phlebectasia and laryngocoele, which can easily be differentiated from one another on imaging.1 Congenital lung herniation is the protrusion of the lung apex into the cervical region due to partial absence or laxity of Sibson’s fascia, or increased space between the scalenus anterior and sternocleidomastoid muscles.6 Unilateral or bilateral congenital lung herniation manifests in the first year of life as compressible supraclavicular or suprasternal neck mass with crepitus during raised intrathoracic pressure. It rarely causes chronic cough, hoarseness or stridor from external compression of the trachea or transient impairment of jugular venous drainage.6 As it tends to resolve spontaneously, surgery is only warranted if there is incarceration of the lung apex or significant compression of nearby structures. Jugular phlebectasia, a congenital fusiform dilatation of the jugular vein usually affecting the right internal jugular vein,7 presents as a compressible lateral neck swelling rather than a midline mass during the Valsalva manoeuvre. Diagnosis is made from ultrasonography with colour Doppler flow imaging, which identifies local dilatation of the affected vein on Valsalva’s manoeuvre.7 Management is conservative unless complications such as thrombosis, Horner’s syndrome or cosmetically disfiguring lesions occur. Laryngocoele (internal, external or mixed type) is an abnormally dilated laryngeal saccule arising between the laryngeal ventricular folds. External laryngocoele herniates through the thyrohyoid membrane, presenting as a neck swelling with the Valsalva manoeuvre.8 It can occur in children but typically affects men in their 50s to 60s.3 Although most are asymptomatic, some can present with acute deterioration of stridor and dyspnoea requiring emergency tracheostomy. MRI is
Journal of Paediatrics and Child Health 51 (2015) 344–346 © 2014 The Authors Journal of Paediatrics and Child Health © 2014 Paediatrics and Child Health Division (Royal Australasian College of Physicians)
345
Midline suprasternal neck mass
SC Su et al.
recommended as laryngocoeles are associated with laryngeal carcinomas.8 In our patient, the diagnosis of superior herniation of the thymus into the neck was confirmed by the characteristic sonographic features of a normal thymus visualised only during increased intrathoracic pressure. The absence of air visualised in the neck mass excluded laryngocoele and lung herniation, and phlebectasia was excluded as the mass was not compressible. We did not proceed with further imaging as the diagnosis was firmly made with the well-described sonographic features, and flexible bronchoscopy did not reveal any tracheal compromise. In summary, neck masses apparent only during increased intrathoracic pressure are rare with a limited differential diagnosis. Ultrasonography should be the first imaging modality of choice. Clinicians are alerted to this condition as it looks alarming, yet simple and prompt diagnosis using minimal investigations avoids unnecessary radiation, biopsy or surgery.
Acknowledgement AC is supported by a NHMRC practitioner fellowship (grant 1058213).
References 1 Wong KT, Lee DLY, Chan MSM, Tsang RKY, Yuen EHY, Ahuja AT. Unusual anterior neck mass visible only during Valsalva’s maneuver in a child. AJR 2005; 185: 1355–7. 2 Senel S, Erkek N, Otgun I, Cinar G, Cifci A, Yoney A. Superior herniation of the thymus into the neck – a familial pattern. J. Thorac. Imaging 2008; 23: 131–4. 3 McDougall CM, Culham G, Seear MD, Chilvers MA. Superior herniation of the mediastinum presenting as an anterior neck mass on straining. Pediatr. Pulmonol. 2012; 47: 710–12. 4 Han BK, Babcock DS, Oestreich AE. Normal thymus in infancy: sonographic characteristics. Radiology 1989; 170: 471–4. 5 Tovi F, Mares AJ. The aberrant cervical thymus. Embryology, pathology, and clinical implications. Am. J. Surg. 1978; 136: 631–7. 6 Mehdi NF, Weinberger M, Abu-Hasan MN. Radiological case of the month. Bilateral congenital apical lung herniation. Arch. Pediatr. Adolesc. Med. 2002; 156: 81–2. 7 Hu X, Li J, Hu T, Jiang X. Congenital jugular vein phlebectasia. Am. J. Otolaryngol. 2005; 26: 172–4. 8 Woo EK, Connor SEJ. CT and MRI appearances of cystic lesions in the suprahyoid neck: a pictorial review. Dentomaxillofacial. Radiol. 2007; 36: 1–9.
Questions 1 The differential diagnosis for an intermittent midline anterior neck mass palpable only during increased intrathoracic pressure includes the below, except: a Laryngocoele b Ectopic thymus c Right internal jugular phlebectasia d Unilateral apical lung herniation e Left external jugular phlebectasia
346
The differential diagnosis of an intermittent neck mass palpable only during raised intrathoracic pressure includes superior herniation of the normal thymus into the neck, laryngocoele, jugular phlebectasia (usually affecting the right internal jugular vein but can also involve the left as well as the external jugular veins) and apical lung herniation (can be unilateral or bilateral). Ectopic thymus produces a neck mass that is palpable all the time, and not palpable only during raised intrathoracic pressure. Answer is (b). 2 The development of the thymus begins in the 6–10th week of gestation and it continues to grow after birth. Which of the following is true? a The thymus reaches its largest weight in adulthood b The largest relative size of the thymus is during puberty c The largest relative size of the thymus is at around 3 years of age d The largest weight of the thymus is at around 3 years of age e The thymus involutes by around 3 years of age The thymus reaches its largest relative size at around 3 years of age, attains its largest weight at puberty and involutes in adulthood. Answer is (c). 3 Neck masses in infants and children are rare and may be alarming to both parents and clinicians. Which of the following statements regarding investigations of neck masses in infants and children is true? a Magnetic resonance imaging should always be the first imaging modality of choice b Superior herniation of the normal thymus into the neck can be diagnosed with ultrasonography with its characteristic appearance c Magnetic resonance imaging is recommended in jugular phlebectasia as it is associated with malignancy d Flexible bronchoscopy should be performed in all asymptomatic infants and children with neck masses e All of the above Magnetic resonance imaging is one of the imaging modalities for investigation of neck masses; however, it does not necessarily have to be the first imaging modality of choice as certain benign conditions can be easily diagnosed with ultrasonography, which is widely available and can be done without general anaesthesia. Conditions such as herniation of the normal thymus into the neck can be diagnosed on ultrasonography as the thymus has characteristic sonographic appearances (well-circumscribed, hypoechoic mass with multiple echogenic foci and linear structures). Magnetic resonance imaging is recommended in cases of laryngocoeles as they are associated with laryngeal carcinomas. In asymptomatic children without stridor or respiratory distress, flexible bronchoscopy is not necessary. Answer is (b).
Journal of Paediatrics and Child Health 51 (2015) 344–346 © 2014 The Authors Journal of Paediatrics and Child Health © 2014 Paediatrics and Child Health Division (Royal Australasian College of Physicians)
Copyright of Journal of Paediatrics & Child Health is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use.
