An indeterminate mucin-producing cystic neoplasm containing an undifferentiated carcinoma with osteoclast-like giant cells: a case report of a rare association of pancreatic tumors

BACKGROUND Only few case reports of mucinous cystic pancreatic neoplasm containing an undifferentiated carcinoma with osteoclast-like giant cells have been described in the literature. In the majority of cases this unusual association of tumors seems related to a favorable outcome. We present the second case of an indeterminate mucin-producting cystic neoplasm containing an area of carcinoma with osteoclast-like giant cells. The specific features of the two histotypes and the rapid course of the disease make our clinical case remarkable. CASE PRESENTATION A 68 year old female came to our attention for a pancreatic macrocystic mass detected with ultrasonography. Her past medical history was silent. The patient reported upper abdominal discomfort for two months; nausea, vomiting or weight loss were not reported. Physical examination revealed a palpable mass in the epigastrium; scleral icterus was absent. Cross-sectional imaging showed a complex mass of the neck and body of the pancreas, characterized by multiple large cystic spaces separated by thick septa and an area of solid tissue located in the caudal portion of the lesion. The patient underwent total pancreatectomy with splenectomy. Pathological examination revealed a mucinous cystic neoplasm with a component of an undifferentiated carcinoma with osteoclast-like giant cells. Because of the absence of ovarian-type stroma, the lesion was classified as an indeterminate mucin-producing cystic neoplasm of the pancreas. The immunohistochemical studies evidenced no reactivity of osteclast-like giant cells to epithelial markers but showed a positive reactivity to histiocytic markers. Numerous pleomorphic giant cells with an immunohistochemical sarcomatoid profile were present in the undifferentiated carcinoma with osteoclast-like giant cells. A rapid tumor progression was observed: liver metastases were detected after 4 months. The patient received adjuvant chemotherapy (Gemcitabine) but expired 10 months after surgery. CONCLUSION Our case confirms that the presence of a solid area in a cystic pancreatic tumor at cross-sectional imaging should raise a suspicion of malignant transformation. The lack of ovarian-type stroma in a pancreatic mucinous cystic neoplasm and the presence of pleomorphic giant cells in an undifferentiated carcinoma with osteoclast-like giant cells could be a marker of a poor prognosis.