Metastatic Squamous Cell Carcinoma to the Gallbladder Presenting as a Diagnostic and Surgical Challenge.

Metastatic spread to the gallbladder is exceedingly rare, representing less than 5% of all gallbladder malignancies, with secondary involvement from head and neck squamous cell carcinoma (SCC) being exceptionally uncommon. We present the case of a 68-year-old male with recurrent metastatic head and neck SCC who arrived with right upper-quadrant pain, nausea, and vomiting. Imaging demonstrated gallbladder distension and wall thickening without cholelithiasis, and subsequent hepatobiliary iminodiacetic acid (HIDA) scanning and magnetic resonance cholangiopancreatography (MRCP) findings supported a diagnosis of acute cholecystitis with cystic duct obstruction. The patient underwent robotic cholecystectomy, during which indocyanine green (ICG) fluorescence cholangiography was utilized to delineate biliary anatomy in the setting of severe inflammation. Intraoperative evaluation revealed a gangrenous gallbladder with cystic duct necrosis. Histopathologic examination demonstrated a 1.5 cm epithelioid/squamoid carcinoma consistent with metastatic SCC, with positive cystic duct margins. The postoperative course was uneventful. Metastatic SCC to the gallbladder is often indistinguishable from benign inflammatory disease on imaging and is commonly diagnosed only after cholecystectomy. While prognosis is largely determined by the burden of systemic disease, surgical excision of isolated lesions may provide symptomatic relief and facilitate diagnosis. This case highlights the importance of considering metastatic disease in patients with a history of malignancy who present with cholecystitis-like symptoms and underscores the value of minimally invasive cholecystectomy in achieving safe management and diagnostic clarity.