Editorial-Orientierung von MedAPI — kein Bestandteil der Kodieranweisung.
C31 covers primary malignant neoplasms arising in the paranasal (accessory) sinuses, including the maxillary, ethmoidal, frontal, and sphenoidal sinuses. These tumors are uncommon and may present late because early symptoms can resemble chronic sinus disease.
Common Histologies
- Squamous cell carcinoma, the most frequent histology
- Sinonasal adenocarcinoma, including intestinal-type adenocarcinoma associated with some occupational wood- or leather-dust exposures
- Adenoid cystic and other salivary-type carcinomas
- Sinonasal undifferentiated carcinoma
- Neuroendocrine carcinoma
- SMARCB1- or SMARCA4-deficient sinonasal carcinoma
- Mucosal melanoma and other rare malignancies
Common Symptoms
Presentation varies by sinus and direction of spread. Findings may include:
- Persistent unilateral nasal obstruction or discharge (R09.81)
- Recurrent epistaxis (R04.0)
- Facial pain (G50.1), pressure (G50.1), swelling (R22.0), or numbness (R20.0)
- Dental pain, loose teeth, or palatal swelling, particularly with maxillary sinus tumors (C31.0)
- Diplopia (H53.2), proptosis (H05.20), visual change (H53.9), or impaired ocular movement (H51.9)
- Headache or cranial neuropathies with skull-base involvement (R51.9)
- Persistent symptoms attributed to sinusitis that do not respond as expected to treatment (J32.9)
Diagnosis
Evaluation commonly includes nasal endoscopy and cross-sectional imaging. CT helps define bony erosion and sinus anatomy, while MRI better assesses orbital, perineural, intracranial, and skull-base extension. Histologic confirmation requires biopsy, with immunohistochemistry and molecular testing when morphology is unusual or undifferentiated. Regional nodal and distant metastatic assessment may include neck imaging, chest imaging, and PET/CT when clinically appropriate.
Staging
Staging is based on the applicable head and neck TNM system and depends on the documented primary subsite. Important features include invasion of adjacent sinus walls, nasal cavity, palate, orbit, pterygoid structures, cranial nerves, skull base, dura, or brain, as well as regional lymph-node and distant metastatic involvement. Resectability and anticipated functional morbidity are assessed separately from stage.
Molecular Markers
Testing is guided by histology. Relevant findings may include HPV association in selected sinonasal carcinomas, IDH2 alterations in some sinonasal undifferentiated carcinomas, NUT rearrangement in NUT carcinoma, and loss of SMARCB1 or SMARCA4 expression in corresponding deficient carcinomas. EBV testing may help classify lymphoepithelial carcinoma. Broad genomic profiling may be considered in advanced or uncommon tumors when it could identify a targeted treatment option.
Common Treatments
Management is multidisciplinary and depends on subsite, histology, extent, resectability, and expected functional impact.
- Surgical resection, using endoscopic, open, or combined approaches when feasible
- Postoperative radiation for many locally advanced tumors or adverse pathologic features
- Concurrent chemoradiation for selected unresectable tumors or when surgery would cause unacceptable morbidity
- Histology-specific systemic therapy for recurrent, metastatic, or non-squamous disease
- Immunotherapy or targeted therapy in appropriately selected advanced cancers
- Supportive rehabilitation addressing vision, swallowing, speech, dental care, and cranial-nerve deficits
Scope Note
C31 identifies the anatomic site of a primary malignant neoplasm of an accessory sinus, with child codes distinguishing maxillary, ethmoidal, frontal, sphenoidal, overlapping, or unspecified sinus sites. It does not encode histology, grade, TNM stage, resectability, molecular profile, or treatment status. It does not include primary malignant neoplasms of the nasal cavity or middle ear, and it should not be used to represent secondary metastatic involvement of a sinus. An overlapping-site code applies when a single primary spans contiguous accessory sinus sites and the point of origin cannot be determined; it is not a substitute for documenting separate primary tumors.