Editorial orientation provided by MedAPI — not part of the coding instruction.
C01 describes a primary malignant neoplasm of the base of tongue, including the posterior third, dorsal surface of the tongue base, and fixed part of the tongue. Anatomically, the tongue base is part of the oropharynx, distinct from the mobile oral tongue.
Common Histologies
- Squamous cell carcinoma, frequently HPV-mediated
- Less commonly, salivary gland–type carcinomas, lymphoepithelial carcinoma, or other rare malignancies arising in this region
Common Symptoms
- Persistent sore throat or difficulty swallowing (R07.0)
- Painful swallowing (R07.0)
- Referred ear pain (H92.09)
- Neck mass from cervical lymph-node involvement (R59.0)
- Voice change (R49.0), globus sensation (R09.A2), bleeding (R49.9), or unexplained weight loss (R63.4)
Small primary tumors may be clinically occult and first present as cervical nodal disease.
Diagnosis
Evaluation commonly includes examination of the oral cavity and neck, flexible nasopharyngolaryngoscopy, and tissue biopsy. CT, MRI, and/or FDG-PET/CT may define local extent, cervical nodal disease, and distant spread. Pathologic assessment generally includes p16 immunohistochemistry or other HPV testing for squamous cell carcinoma of the oropharynx.
Staging
Staging considers primary-tumor size and local invasion, cervical lymph-node involvement, and distant metastasis. For oropharyngeal squamous cell carcinoma, staging differs between HPV-mediated (p16-positive) and p16-negative disease. Midline proximity may permit bilateral lymphatic drainage, so both sides of the neck require assessment.
Molecular Markers
- p16/HPV status is prognostically and staging-relevant in oropharyngeal squamous cell carcinoma.
- PD-L1 expression may help guide systemic therapy in recurrent or metastatic disease.
- Additional molecular testing may be considered for uncommon histologies or advanced disease.
Common Treatments
Management depends on stage, HPV status, resectability, functional considerations, and patient factors. Options may include:
- Definitive radiation therapy for selected localized disease
- Transoral surgery, including robotic or laser approaches, with appropriate neck management
- Concurrent chemoradiation for many locally advanced tumors
- Adjuvant radiation or chemoradiation after surgery when adverse pathologic features are present
- Immunotherapy, chemotherapy, targeted therapy, or palliative radiation for recurrent, unresectable, or metastatic disease
Treatment planning is typically multidisciplinary and should address swallowing, speech, nutrition, dental care, and tobacco or alcohol use when relevant.
Scope Note
C01 identifies the anatomic site of a primary malignant neoplasm of the base of tongue, including the posterior third and fixed tongue base. It does not encode histology, HPV/p16 status, tumor stage, nodal status, distant metastasis, laterality, or treatment. It should not be used for a primary malignancy of the mobile/anterior tongue or for a secondary metastatic deposit involving the tongue; those conditions are classified according to their appropriate primary or secondary site. Associated tobacco history or alcohol-related disorders are documented separately when applicable.