"Mummy what's this on my neck? - A pictorial review of paediatric neck masses"

Transcription

1 "Mummy what's this on my neck? - A pictorial review of paediatric neck masses" Poster No.: C-0405 Congress: ECR 2014 Type: Educational Exhibit Authors: A. Farrugia, A. S. Gatt; Msida/MT Keywords: Education, Ultrasound, PET, MR, Pediatric, Lymph nodes, Head and neck, Congenital DOI: /ecr2014/C-0405 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 60

2 Learning objectives Our educational exhibit aims to outline: The aetiology and appearance of different neck masses in the paediatric population. The use of different imaging modalities in differentiating between diverse neck masses. Testing knowledge regarding common and uncommon neck masses in children Background A wide spectrum of pathologies can present as neck masses in children. The nature of the lump, whether it is painful or not, its consistency and anatomical boundaries, help in formulating a differential diagnosis. The integration of multiple imaging modalities is often necessary to narrow the differential diagnosis. Unlike in adults, many neck masses in children are congenital and/or benign lesions, with neoplastic lesions being less likely. However, neck masses, being palpable and often clinically apparent can be a source of concern for parents and paediatricians alike. We can classify neck masses under several sub-headings, namely inflammatory, congenital, vascular and neoplastic. 1. Inflammatory Suppurative lymphadenitis, abscess, inflamed salivary glands and ranulas (simple vs plunging/diving). 2. Congenital Thyroglossal duct cyst, branchial cleft cysts (I - IV), lingual thyroid tissue and dermoid / epidermoid cysts. 3. Neoplastic Lymphoma, thyroid mass, salivary gland mass, rhabdomyosarcoma and metastatic disease. Page 2 of 60

3 4. Vascular Lymphatic malformations and venous malformations. The sternocleidomastoid muscle is useful as a landmark when assessing which compartment of the neck the mass arises from. Neck masses in children may also be classified as those that found in the anterior triangle, posterior triangle and those within the sternocleidomastoid muscle itself. Findings and procedure details CASE NUMBER: 1 8 year old girl with a central neck mass, which moves up on tongue protrusion Page 3 of 60

4 Fig. 1: Ultrasound image from a patient with a cyst full of debris and with no Doppler flow within the cyst itself References: Department of Medical Imaging, Mater Dei Hospital, Malta 2013 Page 4 of 60

5 Fig. 2: Ultrasound image showing the cyst, typically situated in the submental region References: Department of Medical Imaging, Mater Dei Hospital, Malta 2013 Page 5 of 60

6 Fig. 3: Ultrasound image with colour Doppler showing debris in the dependent part of the cystic lesion and surrounding colour Doppler flow but no flow within the cyst itself References: Department of Medical Imaging, Mater Dei Hospital, Malta 2013 Page 6 of 60

7 Fig. 4: Ultrasound image showing the location of this cyst in the infra-hyoid region. There is increased through transmission, confirming the fluid content of the lesion. Here, the lesion is seen to be embedded within the strap muscles of the neck. References: Department of Medical Imaging, Mater Dei Hospital, Malta 2013 Questions: What is the differential diagnosis of a midline neck mass in a child? What is the most likely diagnosis? Why is it important to look for thyroid tissue in such patients? Diagnosis: THYROGLOSSAL DUCT CYST Answers: 1. The differential diagnosis includes a thyroglossal duct cyst, dermoid cyst, plunging ranula, branchial cleft cyst, obstructed laryngocoele and ectopic thyroid tissue. Page 7 of 60

8 2. The most likely diagnosis of a midline neck mass which moves upwards on tongue protrusion in a child, is a thyroglossal duct cyst. These cysts arise th 3. from from failed involution of the foetal thyroglossal duct during the 5-6 week of gestation. 50% of cases of thyroglossal duct cysts present under the age of 10, with a second peak in presentation in young adulthood. In patients who have had previous infections or haemorrhage due to previous aspirations of the cysts, a more heterogenous consistency of the lesion, with debris within it may be seen. Fine to coarse internal echoes may be seen in keeping with proteinaceous material. It is important to look for thyroid tissue because if thyroid tissue is not present in its conventional location overlying the thyroid cartilage, the gland may be ectopic. One location of ectopic thyroid tissue may be within the thyroglossal duct cyst itself. Of course, this is of importance if resection of the thyroglossal duct cyst is being considered. CASE NUMBER: 2 11 year old boy presents with swelling in his neck lateral to the right mandibular angle Page 8 of 60

9 Fig. 5: Ultrasound image showing the cyst with echogenic debris within it, posterior to the right sternocleidomastoid muscle References: Department of Medical Imaging, Mater Dei Hospital, Malta 2013 Fig. 6: Ultrasound image showing extension inferior and posterior to the right mandible References: Department of Medical Imaging, Mater Dei Hospital, Malta 2013 Page 9 of 60

10 Fig. 7: Ultrasound image showing the anatomical relationship of the cyst to neighbouring structures and the swirling of contents within the cyst References: Department of Medical Imaging, Mater Dei Hospital, Malta 2013 Questions What is the differential diagnosis? What is the likely diagnosis in a child? Why is there swirling of the cyst contents (as seen in Figure 7)? Page 10 of 60

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12 Fig. 8: Axial CT image showing the anterior and lateral extension of the cyst References: Department of Medical Imaging, Mater Dei Hospital, Malta 2013 Fig. 9: Axial CT image through the lower neck showing the inferior lower extension of the cyst References: Department of Medical Imaging, Mater Dei Hospital, Malta 2013 Page 12 of 60

13 Fig. 10: Axial T2W MRI image showing the inferior extension of the cyst References: Department of Medical Imaging, Mater Dei Hospital, Malta 2013 Page 13 of 60

14 Fig. 11: Coronal T2W MRI image showing the inferior extension of the cyst References: Department of Medical Imaging, Mater Dei Hospital, Malta 2013 On CT / MRI, the beak sign refers to a curved rim of tissue pointing medially between the internal and external carotid arteries (pathognomonic) and slight enhancement of the capsule, which becomes significant when infected. On concern is the fact that children are more radio-sensitive than adults. Thus, there must be a balance between optimal diagnostic studies which answer the clinical question and use the lowest possible dose exposure. It is important to keep in mind that the benefits of an indicated CT scan far outweigh the risks from ionizing radiation. Page 14 of 60

15 Diagnosis: SECOND BRANCHIAL CLEFT CYST Answers The differential diagnosis includes a second branchial cleft cyst, submandibular gland cyst, necrotic cervical lymph node, cystic lymphangioma and cervical abscess. This is a second branchial cleft cyst. These cysts result from incomplete nd 3. obliteration of 2 branchial cleft tract resulting in sinus tract / fistula / cyst. Second branchial cleft cysts make up 75% of all branchial cleft cysts. There is a smooth, thin-walled cystic mass at the angle of the mandible. There is displacement of the sternocleidomastoid muscle posteriorly, the carotid artery and jugular vein posteromedially and the submandibular gland anteriorly. It shows no Doppler flow within it, has posterior acoustic enhancement and increased through transmission confirming its cystic nature. The swirling of cyst contents occurs due to haemorrhage within the cyst itself. When infected, these cysts have an ill-defined thick wall with internal debris and septations, secondary to repeated infections or haemorrhage. Infection may result in increased wall thickness and increased density of contents. Some however demonstrate a semi-solid appearance with uniform internal echoes, likely due to the presence of cholesterol crystals, mucus, debris, lymphocytes or epithelial cysts. The lining of a branchial cleft cyst contains lymphoid tissue, which may increase in size during infection, thus branchial cleft cysts may present soon after an upper respiratory tract infection. Simple uninfected branchial cleft cysts have a well-defined epithelial lining and are anechoic, having no internal debris and showing posterior acoustic enhancement and increased through transmission. Occasionally, a second branchial cleft cyst may be associated with a sinus or fistula that opens into the tonsillar fossa. The tract descends along the anterior border of the sternocleidomastoid muscle and may open onto the skin surface at any point along this path. CASE NUMBER: 3 5 year old boy with a history of recent upper respiratory tract infection presents with multiple palpable swellings on either side of the neck Page 15 of 60

16 Fig. 12: Ultrasound image showing reniform shaped cervical lymph nodes with a hyperechoic fatty vascular hilum References: Department of Medical Imaging, Mater Dei Hospital, Malta 2013 Page 16 of 60

17 Fig. 13: Ultrasound image showing an 8mm jugulo-digastric cervical lymph node References: Department of Medical Imaging, Mater Dei Hospital, Malta 2013 Page 17 of 60

18 Fig. 14: Ultrasound image showing a left cervical lymph node in the mid-jugular region (level III) having a short-axis measurement of 7mm References: Department of Medical Imaging, Mater Dei Hospital, Malta 2013 Questions Describe the ultrasound findings. What is the most likely diagnosis? What is the management of this condition? Diagnosis: BENIGN CERVICAL LYMPHADENOPATHY Answers Page 18 of 60

19 There are hypoechoic lesions in the neck bilaterally, with a maximum shortaxis diameter of 8mm and an oval shape. They have an echogenic central part with vascularity within it. Cervical chain lymph nodes with no pathological features of concern are seen, likely reactive lymphadenopathy. Useful sonographic features for identifying pathologic lymph nodes include a round contour, absence of an echogenic hilus, intranodal necrosis, calcifications, ill-defined borders, nodal matting and adjacent soft-tissue oedema. Acute bilateral cervical lymphadenopathy is often caused by a viral upper respiratory tract infection or streptococcal pharyngitis. Acute unilateral cervical lymphadenitis is caused by streptococcal or staphylococcal infection in 40% to 80% of cases. The most common causes of subacute or chronic lymphadenitis are cat scratch disease, mycobacterial infection, and toxoplasmosis. Supraclavicular or posterior cervical lymphadenopathy carries a much higher risk for malignancy than does anterior cervical lymphadenopathy. Children with cervical lymphadenopathy are treated conservatively. Most enlarged lymph nodes are caused by an infectious process, likely viral. Antibiotics should be given only if a bacterial infection is suspected. CASE NUMBER: 4 9 year old girl presents with an enlarging swelling in the lateral aspect of the left side of the neck Page 19 of 60

20 Fig. 15: Ultrasound images showing large partly-cystic masses with echogenic foci within them References: Department of Medical Imaging, Mater Dei Hospital, Malta 2013 Page 20 of 60

21 Fig. 16: Ultrasound images showing multiple hypoechoic foci within hyperechoic lesions with a lobulated contour References: Department of Medical Imaging, Mater Dei Hospital, Malta 2013 Questions What are the ultrasound findings in this case? Is this likely a benign or malignant in aetiology? What is the differential diagnosis and what is the most likely diagnosis? Diagnosis: MALIGNANT CERVICAL LYMPHADENOPATHY Answers These masses are round with a heterogenous echotexture. There is loss of the central fatty hilum with eccentric thickening of the cortex and cystic necrotic areas are present within. They have ill-defined capsular margins, suggestive of surrounding soft-tissue invasion. If colour Doppler imaging was performed, there would likely be peripheral vascularity rather than a central vascular supply, with avascular areas within these lesions. The vasculature typically shows a high resistance waveform with resistive indices above 0.8. This is attributed to increased cellularity within an infiltrated lymph node. However, this is not always the case, as malignant lymph nodes with predominant necrosis may show low resistance flow due to the loss in cellularity. Together, these signs may help in the differentiation of malignant from benign lymphadenopathy. Cervical lymphadenopathy most commonly represents a response to a benign local or generalized infection, but occasionally it might herald the presence of a more serious disorder such as malignancy. The features mentioned in (a) and seen in this case point towards a malignant aetiology of these lymph nodes. More than 25% of malignant tumours in children occur in the head & neck region and cervical lymph nodes are the most common site. During the first years of life, neuroblastoma and leukaemia are the most common tumours associated with cervical lymphadenopathy followed by rhabdomyosarcoma and Non-Hodgkin's lymphoma. Over the age of 6, Hodgkin's lymphoma is the most common tumour associated with cervical lymphadenopathy surpassing Non-Hodgkin's lymphoma and rhabdomyosarcoma, respectively. Differential diagnoses include malignant lymphadenopathy, an infected branchial cleft cyst, cystic hygroma or an infected laryngocoele. The presence of cervical lymphadenopathy is one of five diagnostic criteria for Kawasaki disease. Generalized lymphadenopathy might be a feature of systemic onset juvenile rheumatoid arthritis, systemic lupus erythematosus, Page 21 of 60

22 or serum sickness. Cervical lymphadenopathy has been reported following immunization with diphtheria-pertussis-tetanus, poliomyelitis, or typhoid fever vaccine. Failure of regression after 4 to 6 weeks might be an indication for a diagnostic biopsy. An excisional biopsy with microscopic examination of the lymph node might be necessary to establish the diagnosis if there are symptoms or signs of malignancy or if the lymphadenopathy persists or enlarges in spite of appropriate antibiotic therapy and the diagnosis remains in doubt. The biopsy should be performed on the largest and firmest node that is palpable. CASE NUMBER: 5 A 12 year old girl presents with an anterior midline neck swelling of long-standing Page 22 of 60

23 Fig. 17: Ultrasound images showing a hypoechoic nodule within the right thyroid lobe References: Radiology Department, DaVinci Hospital, Malta 2013 Page 23 of 60

24 Fig. 18: Ultrasound image showing a hypoechoic nodule in the left thyroid lobe References: Radiology Department, DaVinci Hospital, Malta 2013 Fig. 19: Ultrasound image of the dominant partly-solid partly-cystic nodule within the right thyroid lobe References: Radiology Department, DaVinci Hospital, Malta 2013 Page 24 of 60

25 Fig. 20: Ultrasound images with colour Doppler flow showing increased vascularity around the central cystic lesion but absent vascular flow within it and second image shows a reactive lymph node with central Doppler flow and a preserved reniform shape References: Radiology Department, DaVinci Hospital, Malta 2013 Questions Describe the ultrasound findings shown above. What is the diagnosis? Is there a differential diagnosis? Diagnosis: MULTINODULAR GOITRE Answers There are multiple hypoechoic lesions within an enlarged thyroid gland. The nodules have well-defined margins and demonstrate intranodular vascularity. The thyroid gland itself has a heterogenous internal echopattern with multiple septations and cystic parts. Ultrasound features for each thyroid nodule should be evaluated and management is in a similar way as for solitary thyroid nodules. If surgical resection of a dominant hypoechoic nodule is indicated based on risk factors, ultrasound features or FNA sent for cytology, the presence of several bilaterally thyroid nodules should prompt consideration for a total thyroidectomy. Findings are in keeping with a multinodular goiter - girl had a maternal grandmother with a history of total thyroidectomy for an unknown cause. Multinodular goiters are rather uncommon in children. Thyroid nodules < 1cm and with benign features are usually safely monitored on serial ultrasound examinations. CASE NUMBER: 6 Page 25 of 60

26 3 week old neonate who presented to the paediatrician in view of a bulge on the right side of his neck Fig. 21: Ultrasound images from a two week old neonate showing a comparison between the right and left anterior neck structures References: Department of Medical Imaging, Mater Dei Hospital, Malta 2013 Questions Describe the ultrasound findings. What is the diagnosis? Diagnosis: FIBROMATOSIS COLLI Answers In both neonates, there is an enlarged right sternocleidomastoid muscle with no focal lesion within it. Fibromatosis colli refers to fibrosis or intra-muscular haemorrhage within the sternocleidomastoid muscle itself. Presentation is usually at 2-4 weeks Page 26 of 60

27 of age, more prevalent in males, with a unilateral neck mass and parental complaint of the child holding the head onto one side (torticollis due to muscle contraction). Children with breech presentation or those with a difficult delivery are at increased risk of torticollis. Usually the condition resolves spontaneously with gentle stretching exercises and physiotherapy. Surgical intervention is rarely necessary. On ultrasound, fibromatosis colli appears as a fusiform thickening of the sternocleidomastoid muscle and may be decreased or increased echogenicity in the affected muscle, which is heterogenous. On CT, fibromatosis colli is seen as isoattenuating homogenous muscle enlargement. On MRI, diffuse abnormal high signal intensity within the muscle on T2WI is present. Gradual spontaneous regression usually occurs by the age of 2. CASE NUMBER: 7 12 year old girl with a mass just inferior to her right ear Page 27 of 60

28 Fig. 22: Axial CT image showing a cystic lesion posterior to the right angle of the mandible References: Department of Medical Imaging, Mater Dei Hospital, Malta 2013 Page 28 of 60

29 Fig. 23: Axial CT image showing the posterior extension of the cystic lesion References: Department of Medical Imaging, Mater Dei Hospital, Malta 2013 Page 29 of 60

30 Fig. 24: Axial CT image showing the medial deviation of the great vessels of the right neck by the cystic structure References: Department of Medical Imaging, Mater Dei Hospital, Malta 2013 Questions What are the CT findings? What is the most likely diagnosis? Page 30 of 60

31 Diagnosis: CYSTIC HYGROMA Answers There is a well-defined hypodense lesion, just lateral to the right carotid sheath. It contains homogenous fluid within it. Cystic hygroma is the largest in the spectrum of congenital lymphatic malformations or lymphangiomas. These are lymphatic malformations with large lymphatic spaces. 75% of all lymphatic malformations occur in the neck. In infants, these are commonly seen in the posterior triangle and in the cervico-thoracic junction. A cystic hygroma is a collection of large, dilated lymphatic spaces resulting from failure of a primordial lymph sac to re-establish communication with central venous system from which it arose. Typically presents in early life and if large, may also be diagnosed antenatally. 65% are present at birth and 90% are found by the age of 2 years. If large and extending centrally, the child with a cystic hygroma may present with stridor since the trachea and oesophagus are compressed and / or displaced. On CT, it appears as a low-attenuating, non-enhancing, cystic structure, which may be multi-lobulated lesion deep to the sternocleidomastoid muscle and displacing the carotid artery and internal jugular vein anteriorly and medially. Surgical excision is the first-line treatment for cystic hygromas. CASE NUMBER: 8 4 week old neonate presented with increasing swelling of the right cheek since 2 weeks post-natally Page 31 of 60

32 Fig. 25: Ultrasound image of the right cheek anterior to the ear showing a parotid gland replaced by a partly-solid, partly-cystic structure References: Department of Medical Imaging, Mater Dei Hospital, Malta 2013 Page 32 of 60

33 Fig. 26: Ultrasound images of the left parotid gland for comparison (intra-parotid lymph nodes are seen in its superficial aspect) References: Department of Medical Imaging, Mater Dei Hospital, Malta 2013 Questions 1. Describe the ultrasound findings. 2. What is the differential diagnosis and most likely diagnosis in this case? Page 33 of 60

34 Fig. 27: Coronal T2W MRI image showing a hyperintense lesion in the right parotid gland with multiple vascular flow voids within it References: Department of Medical Imaging, Mater Dei Hospital, Malta 2013 Page 34 of 60

35 Fig. 28: Coronal T2W MRI image showing the vascular flow voids within it and the expansile nature of the parotid lesion References: Department of Medical Imaging, Mater Dei Hospital, Malta 2013 Diagnosis: HAEMANGIOENDOTHELIOMA Answers 1. The right parotid gland is enlarged by a mass within it, which has a lobulated border. The mass arises from the superficial part of the gland but extends into the deep part of the gland. Page 35 of 60

36 2. A haemangioendothelioma / congenital capillary haemangioma is the most common parotid gland tumour in childhood. It occurs more commonly in girls than boys (3F: 1M). They usually become prominent in the first few months of life and are most commonly diagnosed during the first year of life. They show rapid growth in the first months of life and then spontaneously regress. Colour Doppler ultrasound shows an enlarged, highly vascular and heterogenous parotid gland and a normal homogenous parotid gland on the normal contralateral side. Typically, on ultrasound it appears as an enlarging mass replacing most or all of the parotid gland with a lobular internal structure, large intratumoral blood vessels, fine echogenic internal septations and a mildly lobulated contour. MRI is the best imaging technique for assessment of a parotid haemangioendothelioma. This lesion is isointense to muscle on the precontrast T1 and is heterogeneously hyperintense on axial T2 and STIR with evidence of lobulation and septa often seen within the lesion. On T2 MRI images, it has a typical hyperintense appearance containing vascular flow voids. Intense contrast enhancement of the lesion, apart from the flow voids, is typical. Usually, intratumoral vessels are branches of the external carotid artery and / or tributaries of the retromandibular vein. Extension into the deep lobe of the parotid gland may also be seen, however extension beyond the parotid gland itself is uncommon. Reliable features on ultrasound reduce the need for MR imaging in infants with this lesion. However, if sonographic features are atypical or there is extension of the lesion into the deep lobe of the parotid gland, MRI is indicated. Also, a mass which is associated with facial nerve symptoms should be evaluated with MRI since this is the only modality that can consistently demonstrate the facial nerve. Solid lymphatic malformations usually show extension beyond the parotid gland itself and do not contain prominent blood vessels. Vascular malformations grow at about the same rate as the child rather than regress, which also helps distinguish them from haemangioendotheliomas. CASE NUMBER: 9 6 year old boy with swelling anterior to the left ear Page 36 of 60

37 Fig. 29: Enlarged parotid gland with multiple cystic spaces are seen within the parotid gland with a paucity of parotid tissue noted References: Department of Medical Imaging, Mater Dei Hospital, Malta 2013 Page 37 of 60

38 Fig. 30: Heterogenous parotid gland with a lobulated contour and multiple cystic structures within a distorted parotid gland References: Department of Medical Imaging, Mater Dei Hospital, Malta 2013 Questions Describe the ultrasound findings. What is the most likely diagnosis? Page 38 of 60

39 Fig. 31: Coronal MRI T1W image post-contrast administration showing intense enhancement of the left parotid lesion, which is again seen as separate from the masseter muscle Page 39 of 60

40 References: Department of Medical Imaging, Mater Dei Hospital, Malta 2013 Fig. 32: Pre-contrast coronal MRI T1W image showing the left parotid lesion, seen to be separate from the left masseter muscle References: Department of Medical Imaging, Mater Dei Hospital, Malta 2013 Diagnosis: LYMPHANGIOMA Page 40 of 60

41 Answers There are multiple cystic foci within an enlarged parotid gland. Interspersed parotid tissue is highly vascular. Lymphangiomas are congenital malformations of the lymphatics that may involve the parotid gland. Approximately 65% of lymphangiomas are present at birth, and 90% are detected by age 2 years. They typically manifest as a soft, asymptomatic neck mass and facial asymmetry is common. Infection or hemorrhage may complicate lymphangiomas, which unlike hemangiomas rarely undergo spontaneous regression. On ultrasound, lymphangiomas have a cystic echotexture, with thin septations, although solid foci may be present. On CT, they are heterogeneous with septations and cystic areas. The mass is often multispatial and slides itself in between adjacent structures. It often contains fluid-fluid levels, and solid portions of the lesion may enhance. On MR imaging, lymphangiomas are heterogeneous with multiple cystic areas demonstrating low signal intensity on T1W and hyperintensity on T2W images. Haemorrhage into the lesion frequently occurs, causing multiple fluid-fluid interfaces with variable signal intensity depending on the age of the blood products. This imaging feature, although not always present, strongly suggests a diagnosis of lymphangioma rather than hemangioma. Contrast-enhanced imaging may show enhancement of the solid portions of the lesion but is not required when a typical multispatial, insinuating multicystic mass with bloodfluid interfaces is seen. Images for this section: Page 41 of 60

42 Fig. 12: Ultrasound image showing reniform shaped cervical lymph nodes with a hyperechoic fatty vascular hilum Page 42 of 60

43 Fig. 13: Ultrasound image showing an 8mm jugulo-digastric cervical lymph node Page 43 of 60

44 Fig. 14: Ultrasound image showing a left cervical lymph node in the mid-jugular region (level III) having a short-axis measurement of 7mm Page 44 of 60

45 Fig. 15: Ultrasound images showing large partly-cystic masses with echogenic foci within them Page 45 of 60

46 Fig. 16: Ultrasound images showing multiple hypoechoic foci within hyperechoic lesions with a lobulated contour Fig. 17: Ultrasound images showing a hypoechoic nodule within the right thyroid lobe Page 46 of 60

47 Fig. 18: Ultrasound image showing a hypoechoic nodule in the left thyroid lobe Fig. 19: Ultrasound image of the dominant partly-solid partly-cystic nodule within the right thyroid lobe Page 47 of 60

48 Fig. 20: Ultrasound images with colour Doppler flow showing increased vascularity around the central cystic lesion but absent vascular flow within it and second image shows a reactive lymph node with central Doppler flow and a preserved reniform shape Fig. 21: Ultrasound images from a two week old neonate showing a comparison between the right and left anterior neck structures Page 48 of 60

49 Fig. 23: Axial CT image showing the posterior extension of the cystic lesion Page 49 of 60

50 Fig. 24: Axial CT image showing the medial deviation of the great vessels of the right neck by the cystic structure Page 50 of 60

51 Fig. 22: Axial CT image showing a cystic lesion posterior to the right angle of the mandible Page 51 of 60

52 Fig. 26: Ultrasound images of the left parotid gland for comparison (intra-parotid lymph nodes are seen in its superficial aspect) Page 52 of 60

53 Fig. 27: Coronal T2W MRI image showing a hyperintense lesion in the right parotid gland with multiple vascular flow voids within it Page 53 of 60

54 Fig. 28: Coronal T2W MRI image showing the vascular flow voids within it and the expansile nature of the parotid lesion Page 54 of 60

55 Fig. 25: Ultrasound image of the right cheek anterior to the ear showing a parotid gland replaced by a partly-solid, partly-cystic structure Page 55 of 60

56 Fig. 29: Enlarged parotid gland with multiple cystic spaces are seen within the parotid gland with a paucity of parotid tissue noted Page 56 of 60

57 Fig. 30: Heterogenous parotid gland with a lobulated contour and multiple cystic structures within a distorted parotid gland Page 57 of 60

58 Fig. 32: Pre-contrast coronal MRI T1W image showing the left parotid lesion, seen to be separate from the left masseter muscle Page 58 of 60

59 Fig. 31: Coronal MRI T1W image post-contrast administration showing intense enhancement of the left parotid lesion, which is again seen as separate from the masseter muscle Page 59 of 60

60 Conclusion The importance of familiarity with common paediatric neck masses helps to narrow the differential and plan imaging accordingly when these are encountered clinically. Certain imaging modalities are better suited for particular pathologies, as noted in the cases above. Ultrasound is a great diagnostic tool to obtain real-time images with minimal patient discomfort. The use of cross-sectional imaging, namely CT and MRI in children is steadily increasing. Although one should always strive to avoid ionizing radiation, in acute and / or atypical cases, judicious use of CT is warranted in children. Personal information References 1. Pediatric Imaging: The Fundamentals, 1e by Lane F. Donnelly MD (Dec 4, 2008) 2. Tunkel, DE. Safer Radiologic Imaging of Otolaryngologic Disease in Children. Otolarygnol Head and Neck Surgery 2012; 147(1): Page 60 of 60