Acute cholecystitis revealing gastric adenocarcinoma with osseous metastasis: a case report and review of the literature.

INTRODUCTION AND IMPORTANCE: Gastric cancer is a major cause of cancer-related death worldwide and is often difficult to diagnose, especially in advanced stages. Its clinical presentation varies widely, ranging from common gastrointestinal symptoms (epigastric pain, dyspepsia, and weight loss) to atypical manifestations caused by its metastatic spread. Gastric adenocarcinoma most frequently metastasizes to lymph nodes, the liver, and the peritoneum, whereas bone metastases are rare and associated with poor prognosis. In some cases, bone metastases are detected before the primary gastric tumor is diagnosed, as their nonspecific symptoms can delay identification. Gallbladder metastases are uncommon and are more often linked to breast or lung cancers, or melanoma; metastasis from gastric adenocarcinoma is exceptionally rare. This article presents a rare case of acute cholecystitis revealing gastric adenocarcinoma with bone metastases, along with a literature review to better understand its clinical, diagnostic, and therapeutic implications. CASE PRESENTATION: A 57-year-old woman was admitted with 1 week of abdominal pain. She was clinically stable, non-icteric, with diffuse abdominal tenderness. Laboratory tests revealed leukocytosis (15 530/mm3) and elevated CRP (209 mg/L). Imaging showed acute calculous cholecystitis without biliary duct dilatation, associated with retroperitoneal infiltration encasing the ureters and causing bilateral hydronephrosis (right predominant), as well as multiple osteosclerotic bone lesions. She underwent cholecystectomy. Histopathology demonstrated secondary gallbladder involvement by adenocarcinoma of suspected upper gastrointestinal origin. Bone marrow biopsy revealed metastatic adenocarcinoma with signet-ring cell features, immunohistochemically suggestive of gastric origin. Bilateral double-J ureteral stents were placed, and the patient was referred for endoscopic evaluation and palliative management. CLINICAL DISCUSSION: This case report describes an exceptionally rare clinical presentation in which acute cholecystitis revealed an underlying gastric adenocarcinoma with bone metastases. Although gastric cancer is the fifth most common malignancy worldwide and a leading cause of cancer-related mortality, bone metastases occur in a minority of cases and are seldom the initial manifestation. Acute cholecystitis secondary to metastatic gastric involvement of the gallbladder is even more uncommon. Several pathophysiological mechanisms may account for this presentation, including lymphatic or direct tumor spread to the gallbladder, hematogenous dissemination explaining concomitant bone metastases, and peritoneal carcinomatosis with secondary gallbladder infiltration. The nonspecific nature of symptoms often complicates preoperative diagnosis and may delay the identification of the primary malignancy. Diagnosis relies on comprehensive imaging, histopathological confirmation following cholecystectomy, and systematic staging investigations to assess metastatic dissemination. Therapeutic management should be individualized, combining surgical intervention for symptom control and diagnostic confirmation with systemic therapy guided by tumor molecular characteristics, and palliative measures when indicated. Given the association with advanced metastatic disease, prognosis is generally poor. This case underscores the importance of considering an underlying malignancy in atypical presentations of acute cholecystitis and highlights the need for thorough diagnostic evaluation and multidisciplinary management. CONCLUSION: Acute cholecystitis revealing a gastric adenocarcinoma with bone metastases remains extremely rare, but it should be considered in the differential diagnosis of atypical presentations. The combination of a surgical approach for symptomatic control and systemic chemotherapy remains the standard in the management of metastatic patients.