Squamous cell carcinoma of the cystic duct: A case report and literature review

RATIONALE: Pure squamous cell carcinoma (SCC) of the gallbladder is a rare malignant biliary tract tumor predominantly found in the body and neck of the gallbladder. However, its occurrence in the cystic duct is even rarer. Given its rarity, no established guidelines or consensus currently exist regarding the treatment of pure SCC of the gallbladder. We report an unusual case of SCC originating from the cystic duct with the intent of providing insights into the therapeutic approach for this type of malignancy. PATIENT CONCERNS: A male patient presented to our hospital with acute cholecystitis. Unexpectedly, imaging revealed gallbladder malignancy. DIAGNOSES: Pathologic examination after surgery confirmed SCC of the cystic duct. INTERVENTIONS: Despite elevated bilirubin levels, we were able to exclude hilar involvement, enabling radical tumor resection. Intraoperatively, we discovered that the tumor was located in the cystic duct, a site associated with a high likelihood of invasion into neighboring organs. The tumor demonstrated a predominantly exophytic growth pattern, which prompted us to refrain from extending the resection range, thereby striking a balance between complete tumor removal and surgical trauma. We performed liver wedge resection only to ensure a negative resection margin while preserving the anatomical structure to the greatest extent possible. Postoperative recovery was rapid and uncomplicated. Pathological examination confirmed pure SCC, which led us to initiate a regimen of nab-paclitaxel and cisplatin, which is known to be effective in other organ SCCs. Remarkably, the patient experienced a rare and severe posttreatment cardiovascular event. Consequently, we switched the patient to a chemotherapy regimen of gemcitabine and cisplatin, which ultimately yielded positive clinical outcomes. OUTCOMES: no evidence of tumor recurrence was observed within 1 year after surgery. LESSONS: The diagnosis and therapeutic strategy for rare tumors such as gallbladder SCC should be meticulously tailored based on their unique characteristics to optimize postoperative patient outcomes.