Editorial orientation provided by MedAPI — not part of the coding instruction.
C23 identifies a primary malignant neoplasm of the gallbladder. Gallbladder cancer is often discovered incidentally after cholecystectomy performed for presumed benign gallstone disease or cholecystitis.
Common Histologies
- Adenocarcinoma is the predominant histology, including biliary-type and less common papillary or mucinous variants.
- Rare tumors include adenosquamous or squamous carcinoma, neuroendocrine neoplasms, and other uncommon histologies.
Common Symptoms
Early disease may be asymptomatic or resemble benign biliary disease. Presentations can include:
- Right upper-quadrant or epigastric pain (R10.11)
- Nausea (R11.0), anorexia (R63.0), or weight loss (R63.4)
- Jaundice or pruritus from biliary obstruction (K83.1)
- Palpable mass or systemic symptoms in advanced disease (R22.9)
Diagnosis
Evaluation commonly includes abdominal ultrasonography and contrast-enhanced CT or MRI/MRCP. Pathologic examination of a cholecystectomy specimen may establish an incidental diagnosis. Biopsy is generally used when histologic confirmation is needed before systemic therapy or when disease is unresectable; potentially resectable tumors may proceed directly to surgical assessment.
Laboratory testing can include liver chemistries and the tumor markers CA 19-9 and CEA, although these markers are neither sufficiently sensitive nor specific for diagnosis.
Staging
Gallbladder cancer is staged using the TNM system. Important factors include:
- Depth of invasion through the gallbladder wall
- Extension into the liver or adjacent organs
- Regional lymph-node involvement
- Distant metastatic disease
Cross-sectional imaging evaluates local resectability and metastatic spread. Selected patients may undergo staging laparoscopy because small-volume peritoneal or hepatic metastases can be radiographically occult.
Molecular Markers
For advanced disease, comprehensive molecular profiling may identify actionable alterations. Depending on histology and local practice, testing may include:
- HER2 amplification or overexpression
- Mismatch-repair deficiency or microsatellite instability
- NTRK fusions and other rare targetable alterations
- Broader genomic profiling for clinical-trial eligibility
Actionability depends on the specific alteration, treatment setting, and current regulatory guidance.
Common Treatments
- Localized disease: Surgical resection offers the principal chance of cure. T1a tumors incidentally confined to the lamina propria are often adequately treated by simple cholecystectomy. More deeply invasive but resectable tumors may require oncologic re-resection, typically including adjacent liver tissue and regional lymphadenectomy.
- Adjuvant therapy: Capecitabine is commonly considered after curative-intent resection; chemoradiation may be considered selectively, particularly with positive margins or other high-risk features.
- Unresectable or metastatic disease: Systemic therapy commonly uses a gemcitabine- and cisplatin-based regimen with immunotherapy when appropriate. Subsequent therapy may include fluoropyrimidine-based chemotherapy, biomarker-directed treatment, or clinical-trial participation.
- Supportive care: Biliary drainage, pain management, nutritional support, and treatment of cholangitis or other complications may be required.
Scope Note
C23 encodes the anatomic site of a primary malignant neoplasm of the gallbladder. It does not encode histologic subtype, grade, TNM stage, molecular findings, resectability, treatment status, or recurrence. Metastatic involvement of the gallbladder from another primary site is not classified as a primary C23 malignancy, and distant metastases from gallbladder cancer may require separate secondary-neoplasm codes where applicable.