Malignant Tumors of the Floor of the Mouth Workup

Updated: Feb 25, 2022
  • Author: Ethem Guneren, MD; Chief Editor: Arlen D Meyers, MD, MBA  more...
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Laboratory Studies

See the list below:

  • For systematic evaluation of the patient, obtain the following laboratory studies:

    • A complete blood count (CBC) is needed. This test is used to assess the risk for anemia or infection and rule out metabolic anomalies; include measurements of electrolytes and kidney function, especially if patient is receiving diuretics.

    • Liver function studies are necessary if the patient has significant risk of liver damage due to alcoholism or a history of hepatitis.

    • Bleeding and clotting tests and urinalysis are needed because these patients are candidates for surgery.

    • Type and cross blood are set aside for transfusion in patients at high risk of significant blood loss.


Imaging Studies

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  • Obtain a plain radiograph to complete the systematic evaluation of the patient to rule out the presence of metastasis to the chest or other cardiopulmonary disease. [1]

  • Plain anteroposterior and lateral cranial radiography and Waters roentgenography are routine.

  • Mandibular orthopantomography (Panorex), CT scanning, and MRI are indicated for large tumors to evaluate the inner cortical periosteum and bone invasion of the mandible and in cases with clinically positive neck involvement.

  • 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. The integrity of cortical bone (mandible) is more accurately assessed with CT scanning, and the integrity of medullary bone (mandible) is more accurately assessed with MRI.


Other Tests

Occasionally, a lesion in the oral cavity appears indistinct and may not be readily visualized on inspection. In these cases, toluidine blue dye can be applied to delineate the area of involvement more clearly.

Toluidine blue stains the nucleus of cells in an area of ulceration but not in areas of intact normal mucosa. The dye is not specific for malignant cells, but it stains areas of ulceration with increased cell turnover or with aberrant cells. The technique is also useful in staining the mucosa of individuals with suspected field cancerization in order to select suspicious sites for biopsy.


Diagnostic Procedures

The examination is completed with endoscopies of the upper respiratory and upper gastrointestinal systems.

Swelling of the floor of the mouth is sometimes difficult to diagnose clinically. With a submandibular mass, gland enlargement due to lithiasis may be difficult to differentiate from duct obstruction and nodal enlargement due to tumor metastasis, in which case plain radiography and CT scanning would not be helpful. In these circumstances, fine-needle aspiration biopsy is necessary. The accuracy of fine-needle aspiration results depends largely on the pathologist's experience with cytologic interpretation, the quality of the specimen submitted, and the proficiency of the person who performs the biopsy. In difficult cases, the use of ultrasonographically assisted fine-needle aspiration is very helpful.

An excisional biopsy should be performed for a small lesion. For deeper and more extensive lesions, an incisional biopsy including healthy tissue margins and adequate tissue samples should be performed.

Sentinel lymph node biopsy is a new technique in staging the clinically N0 (see Staging) neck. Sentinel lymph node evaluation in head and neck squamous cell carcinoma provides a highly accurate staging of N0 necks in oral and particularly in oropharyngeal carcinomas. [4] Lymph node mapping is performed with preoperative lymphoscintigraphy and intraoperative use of a hand-held gamma probe. Tc 99m–labeled nanocolloids are injected around the primary tumor. The sentinel lymph node (identified with dynamic scintigraphy) and the neck dissection specimen are sent separately for histological analysis. The sentinel lymph node and the neck dissection specimen are then assessed for occult metastasis and compared.


Histologic Findings

Squamous cell carcinomas account for more than 90% of oral cancers. Adenocarcinomas are second in frequency. Other tumors include malignancies of the minor salivary glands, including mucoepidermoid and adenoid cystic carcinoma, melanoma, lymphoma, sarcoma, basaloid squamous carcinoma, and very rarely, malignant hemangiopericytoma.

Typically, squamous carcinoma is an ulcerated lesion with indurated edges. It may project from the surface (exophytic) or infiltrate deeply (endophytic). Verrucous carcinoma is a particular lesion that is raised above the surface, having multiple papillae. In the past, it was classified according to pleomorphism and mitosis of the lesion, but this grading is subjective and is of limited value.



After the diagnosis of cancer is pathologically proven, diagnostic staging is based on the clinical evaluation with measurable size of the lesion. It includes information obtained from CT scanning or MRI. Staging occurs before any definitive therapy is instituted. The staging system allows the surgeon to classify a patient in such a way that appropriate therapy can be selected.

The staging systems of the American Joint Committee for Cancer (AJCC) and the International Union Against Cancer (UICC) and end-results reporting are the standard means of describing tumor extent for carcinomas of the oral cavity. The uniformly accepted staging system is the tumor node metastasis (TNM) system. It is a composite of the primary tumor and nodal and systemic metastases substages. [5]

  • T represents the size and extent of the primary tumor.

    • T - Preinvasive cancer (carcinoma in situ)

    • T1 - Tumor of 2 cm or less in greatest dimension

    • T2 - Tumor of more than 2 cm but not more than 4 cm

    • T3 - Tumor of more than 4 cm in greatest dimension

    • T4 - Massive tumor of more than 4 cm in diameter with invasion of the base of the tongue or invasion of the mandible

  • N represents the state of regional lymph node involvement.

    • N0 - No clinical evidence of regional lymph node involvement

    • N1 - Evidence of involvement of single movable homolateral node less than 3 cm in greatest dimension

    • N2 - Evidence of involvement of a single ipsilateral lymph node more than 3 cm but not more than 6 cm in greatest dimension or involvement of multiple ipsilateral lymph nodes, none more than 6 cm in greatest dimension, or involvement of bilateral or contralateral lymph nodes, none more than 6 cm in greatest dimension

      • N2a - Evidence of involvement of a single ipsilateral lymph node, more than 3 cm but not more than 6 cm in greatest dimension

      • N2b - Evidence of involvement of multiple ipsilateral lymph nodes, none more than 6 cm in greatest dimension

      • N2c - Evidence of involvement of bilateral or contralateral lymph nodes, none more than 6 cm in greatest dimension

    • N3 - Evidence of involvement of any fixed regional lymph node or multiple movable regional nodes, one more than 6 cm in greatest dimension

  • M represents the presence of distant metastases.

    • M0 - No clinical evidence of distant metastases

    • M1 - Evidence of distant metastases

  • Stages according to the TNM system are as follows:

    • S1 - T1/N0/M0

    • S2 - T2/N0/M0

    • S3 - T3/N0/M0; T1 or T2 or T3/N1/MO

    • S4 - T4/N0 or N1/M0; any T/N2 or N3/M0; any T/any N/M1