Oral cavity
Squamous cell carcinoma
Floor of mouth

Topic Completed: 1 January 2014

Revised: 1 February 2019

Copyright: (c) 2004-2019, PathologyOutlines.com, Inc.

PubMed Search: Squamous cell carcinoma floor of mouth[TI]

Anshu Jain, M.D., M.B.B.S.
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Cite this page: Jain A Squamous cell carcinoma - floor of mouth. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/oralcavitysccfloorofmouth.html. Accessed August 21st, 2019.
Definition / general
  • Carcinoma of floor of mouth accounts for 28 - 35% of all oral cancers
  • Squamous cell carcinoma (SCC) represents 90 - 95% of malignant tumors of floor of mouth; other very rare types are adenocarcinoma, adenoid cystic carcinoma, melanoma, sarcoma
  • WHO defines squamous cell carcinoma (SCC) as invasive epithelial neoplasm with varying degrees of squamous differentiation
  • Floor of mouth is:
    • Semilunar space over the myelohyoid and hypoglossus muscles, extending from the inner surface of the lower alveolar ridge to the undersurface of the tongue
    • Posterior boundary is base of anterior pillar of tonsil
    • Divided into two sides by the submaxillary and sublingual salivary glands
  • SCC of floor of mouth is categorized under SCC of oral cavity
  • Age: fifth - sixth decade; 85 - 95% are males
  • 5% of all cancers in United States and 50% in India
  • In decreasing order of frequency: anterior, lateral or posterior part of floor of mouth
  • Most frequent premalignant lesions are leukoplakia, erythroplakia and lichen planus, which are associated with carcinoma at diagnosis in 20% of cases
Clinical features
  • Painless, inflamed superficial ulcer with poorly defined margins
  • Frequently asymptomatic for long periods so patient may first present with a neck mass due to metastatic lymphadenopathy
  • May have discomfort or pain under the mobile tongue, difficulty with protraction or swallowing, speech impairment
  • Grade 1: Well differentiated
  • Grade 2: Moderately differentiated
  • Grade 3: Poorly differentiated
  • Grade X: Cannot be assessed
Staging / staging classifications
  • Primary tumor:
    • TX: Cannot be assessed
    • T0: No evidence of primary tumor
    • Tis: Carcinoma in situ
    • T1: Tumor 2 cm or less in greatest dimension
    • T2: Tumor more than 2 cm but not more than 4 cm in greatest dimension
    • T3: Tumor more than 4 cm in greatest dimension
    • T4a: Moderately advanced local disease
      • Tumor invades adjacent structures (e.g. through cortical bone [mandible, maxilla], into deep [extrinsic] muscle of tongue [genioglossus, hyoglossus, palatoglossus and styloglossus], maxillary sinus, skin of face)
    • T4b: Very advanced local disease
      • Tumor invades masticator space, pterygoid plates or skull base or encases internal carotid artery
  • Regional lymph nodes:
    • NX: Cannot be assessed
    • N0: No regional lymph node metastasis
    • N1: Metastasis in a single ipsilateral lymph node, 3 cm or less in greatest dimension
    • N2a: Metastasis in a single ipsilateral lymph node, more than 3 cm but not more than 6 cm in greatest dimension
    • N2b: Metastasis in multiple ipsilateral lymph nodes, none more than 6 cm in greatest dimension
    • N2c: Metastasis in bilateral or contralateral lymph nodes, none more than 6 cm in greatest dimension
    • N3: Metastasis in a lymph node more than 6 cm in greatest dimension
    • Superior mediastinal lymph nodes are considered regional lymph nodes (level VII)
    • Midline nodes are considered ipsilateral nodes
  • Distant metastasis:
    • M0: No distant metastasis
    • M1: Distant metastasis
Radiology description
  • MRI is more reliable than CT scanning in revealing metastatic nodal disease and extracapsular spread of tumor in lymph nodes smaller than 2 cm in diameter
  • Tissue characterization with MRI is superior to that with CT scanning
Prognostic factors
  • Tumor size
  • Nodal involvement
  • Age
  • Overall 5 year survival rate of 30 - 60%; > 90% in stage I, 50 - 75% in stage II, 25 - 40% in stage III / IV
Case reports
  • Stage I / II: surgical resection or radiation therapy (especially brachytherapy)
  • Stage III / IV: combination therapy (including chemotherapy)
  • Primary tumor should be treated radically, with careful evaluation of neck nodes
Clinical images

Images hosted on other servers:

T2 squamous cell carcinoma

Clinical view

Early invasive cancer

Gross description
  • May be exophytic, superficially spreading, infiltrating or ulcerative or mixed
  • Association with local infection makes determination of tumor volume difficult
Microscopic (histologic) description
  • Squamous differentiation, often seen as keratinization with variable "pearl" formation and invasive growth, are required features for SCC
  • Grading based on pleomorphism and mitotic acitivity has limited value
  • Verrucous carcinoma is a subtype raised above surface, having multiple papillae
Microscopic (histologic) images

Images hosted on other servers:

Carcinomatous changes - H&E

Infiltrating basaloid type islands

Dysplastic features

Well differentiated

Verrucous carcinoma

Positive stains
Negative stains
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