Bazan et al. Journal of Medical Case Reports 2011, 5:458 http://www.jmedicalcasereports.com/content/5/1/458 He was scheduled to undergo an elective cholecystect- omy in our center. According to his medical history he had frequent episodes of biliary colic and a cholangitis episode which resolved following endoscopic retrograde cholangiopancreatography papillotomy (ERCP). He had a normal cholangioresonance study. Laparoscopic cholecystectomy revealed an empyema of the gallbladder with stones which made the dissection very difficult because of local inflammation. The gallblad- der was finally removed inside a vinyl extraction bag. The day after surgery, the patient complained of pain at the right hypochondrium and a 2 g hemoglobin decrease was detected. Computed tomography (CT) showed a perihepatic hematoma extending to the right paracolic gutter and no suspicious focus of other neo- plasm was found. Histology revealed a poorly differentiated adenocarci- noma with signet-ring cells (SRCC) extending to the surrounding connective tissue, as well as to the micro- vasculature and invasion of the cystic duct surgical mar- gins (Figure 1). Immunohistochemical staining showed p53 mutation and CK7 were positive; results for CK20 and estrogen were negative. He was histologically classi- fied as a grade 3 (poorly differentiated) with a T2NxMx stage. After his recovery, a radical resection and che- motherapy was proposed, but he rejected this treatment for personal reasons. Several CTs and ultrasound scans were performed as follow up of the hematoma, and no images of wide- spread disease or other complications were found until seven weeks after surgery, when a CT revealed a 19 mm hypodense nodule on the VIII liver segment. We per- formed a fine needle aspiration (FNA) to evaluate this nodule. It was shown on cytology to be a metastatic SRCC. After a new evaluation, the patient rejected che- motherapy again. Nine months later, he presented with jaundice and pain in the right hypochondrium. A new CT showed right Page 2 of 4 pleural effusion with nodular lesions on both pleuras, ret- roperitoneal and right axillary adenopathies, liver masses, peritoneal dissemination and subcutaneous nodules on the chest wall and, at the entrance of the right laparo- scopy trocar, that were described as metastases (Figure 2). The patient was placed on a palliative care program which lasted for one month until his death. Discussion Gallbladder carcinoma is the fifth most common malig- nant neoplasm of the digestive tract, adenocarcinoma being the most frequent histological type [2]. The pre- sence of signet-ring cell proliferation accounts for a highly aggressive pathology, with only a few cases reported [8]. SRCC can arise from virtually any organ but most are from the stomach, breast, and colon [3,9]. Regard- less of the tissue origin, SRCCs frequently metastasize to peritoneal surfaces, regional lymph nodes, ovaries and lungs [9]. Immunohistochemical staining is useful to determine the origin and malignant potential of the signet-ring cells. Gastric SRCC is positive for CK7, CK20 and MUC2 and negative for MUC1. Breast SRCC are mostly CK7-, MUC1-and estrogen-positive and CK20-negative. Colon SRCC are usually CK20- and MUC2-positive and CK7- and MUC1-negative [9-11]. Non-neoplastic signet- ring cells exhibit E-cadherin but no p53 mutation [5]. In our case, immunohistochemical staining of the neoplasm showed p53 mutation and CK7 positive results, with CK20 and estrogen negative results, thus confirming its malignancy and ruling out breast, colon and stomach as the SRCC origin. Therefore, the consistent histological findings (Diastase-PAS), immunohistochemical staining (eliminating the most common primary SRCC neo- plasms: stomach, breast and colon) and in the absence of other primary neoplasms in the imagining studies, the patient was diagnosed with gallbladder SRCC. Figure 1 A: Poorly differentiated gallbladder adenocarcinoma with signet-ring cells (Hematoxylin- eosin, original magnification ×20). B: High power magnification and inset: Signet-ring cell with cytoplasmatic vacuole of mucinous material. (Diastase-PAS stain).