Nasal cavity, paranasal sinuses, nasopharynx
Benign tumors
Salivary gland anlage tumor


Topic Completed: 3 September 2020

Minor changes: 3 September 2020

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PubMed Search: Salivary gland anlage tumor

Josephine K. Dermawan, M.D., Ph.D.
Laura O. Rabinowitz, M.D.
Page views in 2019: 775
Page views in 2020 to date: 884
Cite this page: Dermawan JK, Rabinowitz LO. Salivary gland anlage tumor. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/nasalsalivaryglandanlage.html. Accessed September 29th, 2020.
Definition / general
  • Extremely rare, benign, congenital, biphasic tumor with mixed epithelial and myoepithelial elements of midline nasopharynx
Essential features
Terminology
  • Salivary gland anlage tumor (SGAT)
  • Congenital pleomorphic adenoma
ICD coding
  • ICD-10: D49.0 - neoplasm of unspecified behavior of digestive system
Epidemiology
Sites
  • Located or near midline in the nasopharynx or posterior nasal septum
Pathophysiology
  • Congenital / developmental anomaly, likely represents hamartoma of minor salivary gland origin
Clinical features
  • Obstructive symptoms manifesting as respiratory distress, feeding difficulties or nasal airway obstruction
Diagnosis
  • CT or MRI of the nasal sinuses
  • Diagnosis is by endoscopic biopsy / debulking or surgical resection
Radiology description
Radiology images

Contributed by Scott Poswilko, M.D.

Naso-oropharyngeal mass (T1 axial)

Naso-oropharyngeal mass (T1 coronal)

Naso-oropharyngeal mass (T2 axial)

Prognostic factors
  • Excellent prognosis
  • Curable by surgical resection
Case reports
Treatment
  • Simple surgical excision
Gross description
  • Polypoid, gray, rubbery, grossly encapsulated tissue fragment with homogenous cut surface without necrosis or hemorrhage
Gross images

Images hosted on other servers:

Lobulated mass

Microscopic (histologic) description
  • Surface covered by nonkeratinizing squamous mucosa
  • Multiple submucosal, cellular, solid stromal nodules separated by hypocellular stroma in the center
  • Duct-like epithelial structures and squamous nests with variable keratinization more prominent toward periphery of stromal nodules (Int J Pediatr Otorhinolaryngol 2005;69:149)
  • Internodular epithelial components blend into cellular nodules
  • Cellular stromal nodules composed of mesenchymal appearing, fusiform to spindled to ovoid cells forming short fascicles or trabeculae (Pediatr Pathol Lab Med 1996;16:973)
  • Stromal cells are uniform and show bland cytology with dispersed chromatin, scant eosinophilic cytoplasm and indistinct cell borders (Fetal Pediatr Pathol 2011;30:116)
  • Background hypocellular collagenous stroma with focal chondromyxoid areas
  • Mitotic figures and hemorrhagic necrosis may be present
Microscopic (histologic) images

Contributed by Josephine K. Dermawan, M.D., Ph.D. and Laura O. Rabinowitz, M.D.
Submucosal lobular proliferation

Submucosal lobular proliferation

Nonkeratinizing squamous mucosa

Nonkeratinizing squamous mucosa

Epithelial and mesenchymal components

Epithelial and mesenchymal components

Duct-like structures and calcifications

Duct-like structures and calcifications

Focal chondromyxoid stroma

Focal chondromyxoid stroma

Ovoid to spindled stromal cells

Ovoid to spindled stromal cells


Positive CK7

Positive CK7

Positive P63

Positive p63

Variable SMMS1

Variable SMMS1

Focal S100

Focal S100

Positive stains
Electron microscopy description
Sample pathology report
  • Soft tissue mass, nasopharynx, excision:
    • Salivary gland anlage tumor (see comment)
    • Comment: Histologic sections demonstrate a lobulated nasopharyngeal proliferation which shows mixed epithelial and myoepithelial components. The tumor shows tubules and ducts with variable keratinization with attachment to surface squamous epithelium and multiple cellular spindle cell nodules. Focal chondromyxoid matrix is noted. The epithelial component shows diffuse, strong immunoreactivity for cytokeratin and CK7. The spindle cells show variable to strong immunoreactivity with CK7, p63, SMMS and S100 (rare cells).
Differential diagnosis
Board review style question #1

    A neonate presents with respiratory distress shortly after delivery. Direct laryngoscopy shows an obstructing nasopharyngeal mass. An MRI of the nasal sinus shows a 1.8 cm, polypoid mass in the in the naso-oropharynx. Histology reveals a biphasic, epithelial and mesenchymal neoplasm with ducts and squamous nests and cellular stromal nodules consisting of spindle cells with a myoepithelial immunophenotype. What is the best management for this tumor?

  1. Close observation
  2. Cryotherapy
  3. Neoadjuvant chemotherapy followed by surgical resection
  4. Radiation therapy
  5. Simple endoscopic or surgical resection
Board review answer #1
E. Simple endoscopic or surgical resection

Salivary gland anlage tumor is a benign tumor with excellent prognosis following simple surgical resection. Of all the cases that have been reported, none has recurred following surgical excision.

Comment Here

Reference: Salivary gland anlage tumor
Board review style question #2
    Which of the following features would favor a diagnosis of salivary gland anlage tumor?

  1. Diffuse S100 immunoreactivity in the spindled component
  2. Distant metastasis and death within several months of initial diagnosis
  3. Mesenchymal component with pleomorphic spindle cells showing significant cytologic atypia
  4. Presence of ducts and squamous nests that blend into nodules of spindled cells
  5. Presentation in an adolescent or young male
Board review answer #2
D. Presence of ducts and squamous nests that blend into nodules of spindled cells

Salivary gland anlage tumor is a benign congenital tumor of infancy characterized histologically by the presence of both epithelial and mesenchymal components. Lined by nonkeratinizing squamous epithelium, in the submucosa are cellular stromal nodules composed of uniform, spindled to ovoid cells forming short fascicles, with duct-like epithelial structures and squamous nests in the periphery that blend into the cellular nodules. The spindle cells show variable to strong immunoreactivity with CK7, p63, SMMS and S100 (rare cells).

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Reference: Salivary gland anlage tumor
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