Cystic Neck Mass in A Child

Cystic Neck Mass in A Child
Bernadette L. Koch, MD
DIFFERENTIAL DIAGNOSIS
Common
  • Suppurative Lymph Nodes
  • Abscess
  • Thyroglossal Duct Cyst
  • Lymphatic Malformation
  • Ranula
  • 2nd Branchial Cleft Cyst
Less Common
  • 1st Branchial Cleft Cyst
  • Thymic Cyst
Rare but Important
  • Dermoid and Epidermoid
  • Teratoma
ESSENTIAL INFORMATION
Helpful Clues for Common Diagnoses
  • Suppurative Lymph Nodes
    • Key facts
      • Pus in lymph node = intranodal abscess
    • Imaging
      • Thick enhancing nodal walls with central hypodensity
      • Edema in surrounding fat (cellulitis)
      • ± thickening of muscles (myositis)
      • Associated nonsuppurative adenopathy
      • Nontuberculous mycobacterial adenitis lacks surrounding inflammatory changes
  • Abscess
    • Key facts
      • Conglomeration of suppurative nodes or rupture of node image extranodal abscess
      • Superficial abscesses: Anterior or posterior cervical or submandibular space
      • Deep neck abscesses: Retropharyngeal, parapharyngeal, or tonsillar; may grow rapidly image airway compromise, ± mediastinal extension
      • If anterior to left thyroid lobe, think 4th branchial apparatus anomaly
      • Exclude dental infection and salivary gland calculus as cause of H&N infection
    • Imaging
      • Wide prevertebral soft tissue = cellulitis and edema ± frank abscess
      • False-positive in children if neck not in extended position
      • Rim-enhancing mass with low-attenuation center; majority drainable pus, up to 25% may be phlegmon without drainable pus
      • Edema in surrounding fat (cellulitis), ± thickening of muscles (myositis), occasionally air in abscess cavity
  • Thyroglossal Duct Cyst
    • Key facts
      • Remnant of thyroglossal duct, anywhere from foramen cecum at base of tongue to thyroid bed in infrahyoid neck
      • Treatment = resect cyst, tract, and midline hyoid bone (Sistrunk procedure)
    • Imaging
      • Cyst with minimal rim enhancement
      • At hyoid > suprahyoid = infrahyoid
      • Most in suprahyoid neck are midline; may be paramidline in infrahyoid neck
      • Infrahyoid embedded in strap muscles
      • May contain hyperechoic debris without hemorrhage or infection
      • Increased enhancement and surrounding inflammatory change when infected
      • ± nodularity or calcifications if associated thyroid carcinoma (adults)
  • Lymphatic Malformation
    • Key facts
      • Congenital vascular malformation
      • Variably sized lymphatic channels
      • Present at birth
      • Grows with child
      • Hemorrhage image sudden increase in size
    • Imaging
      • Unilocular or multilocular; macrocystic or microcystic
      • 1 space or trans-spatial
      • Only septations enhance, unless associated with venous malformation
      • Lack high-flow vessels on flow sensitive MR sequences and angiography
      • Fluid-fluid levels
  • Ranula
    • Key facts
      • Simple = postinflammatory retention cyst with epithelial lining; arising in sublingual gland or minor salivary gland, in sublingual space (SLS)
      • Diving = extravasation pseudocyst when ruptures out of SLS into submandibular space (SMS)
    • Imaging
      • Simple = well-defined cyst in SLS
      • Diving = cyst in SLS and SMS; if SLS component collapsed image “tail”
  • 2nd Branchial Cleft Cyst
    • Key facts
      • Characteristic location = at or inferior to angle of mandible, posterolateral to submandibular gland, lateral to carotid space, and anteromedial to sternocleidomastoid muscle (SCM)
      • Uncommon locations = parapharyngeal space, beaking in between internal and external carotid artery, anterior surface of infrahyoid carotid space
    • Imaging
      • Well-defined unilocular cyst in typical location
      • No significant contrast enhancement unless infected
Helpful Clues for Less Common Diagnoses
  • 1st Branchial Cleft Cyst
    • Key facts
      • Remnant of 1st branchial apparatus
      • In or superficial to parotid gland, around pinna or external auditory canal
      • May extend to angle of mandible
      • Proximity to facial nerve important for surgical planning
    • Imaging
      • Well-defined nonenhancing cyst; contrast-enhancing wall with surrounding inflammation if infected
  • Thymic Cyst
    • Key facts
      • Remnant of thymopharyngeal duct
      • 3rd branchial pouch remnant
      • Wall contains Hassall corpuscles
    • Imaging
      • Cystic neck mass along course of thymopharyngeal duct
      • ± solid enhancing thymic tissue
      • Closely associated with carotid sheath
      • May be connected to mediastinal thymus
      • Rarely ruptures into parapharyngeal space
Aug 10, 2016 | Posted by in PEDIATRICS | Comments Off on Cystic Neck Mass in A Child

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