Undifferentiated giant cell type carcinoma of the gallbladder with sarcomatoid dedifferentiation: a case report and review of the literature.

Introduction: Undifferentiated gallbladder carcinoma is a rare entity. Among unusual types of undifferentiated gallbladder carcinoma, giant cell type carcinoma is infrequent and, moreover, very few cases of such neoplasms with osteoclast-like giant cells have been documented. We report a case of undifferentiated gallbladder carcinoma presenting an unusual immunophenotype that was shown to be of giant cell type with sarcomatoid dedifferentiation infiltrated by osteoclast-like multinucleated cells.

Case Presentation: An 84-year-old Greek man presented with right upper quadrant pain, high fever, rigors, anorexia and weight loss during the past month. Clinical examination revealed tenderness in the right upper abdominal quadrant and a palpable gallbladder. Blood tests showed elevated white blood-cell count and transaminases. Abdominal ultrasound and computed tomography demonstrated a markedly distended gallbladder, measuring 16 cm x 8 cm, with oedema and pericholecystic fluid, consistent with gallbladder empyema. After an open cholecystectomy and an uneventful recovery, the patient was discharged on the 4(th) postoperative day. On cut surface, a 2cm solid mass was identified, obstructing the lumen in the neck of the gallbladder. Histopathology and immunohistochemistry offered the diagnosis of an undifferentiated, giant cell type carcinoma of the gallbladder with sarcomatoid dedifferentiation infiltrated with osteoclast-like giant cells.

Conclusions: Undifferentiated, giant cell type carcinoma of the gallbladder with sarcomatoid dedifferentiation infiltrated with osteoclast-like giant cells is a very infrequent neoplasm. Controversy exists over its nature, as related knowledge remains incomplete. Thorough histopathological and immunohistochemical evaluation is imperative for diagnosis. Due to their rarity, the biological behaviour and prognosis of these tumours remain unclear.