Desmoid Mimicking Cystic Pancreatic Lesion: a case report

Desmoid tumors, also called deep or aggressive fibromatosis, are uncommon mesenchymal tumors characterized by proliferation of fibroblasts in an abundant collagen extracellular matrix. They rarely involve the pancreas, and the diagnosis is difficult to make if they do. Only eleven cases have previously been reported involving the pancreas in a review of the literature. In these reported cases, seven patients had solid tumors, three patients had solid tumors with intratumoral cystic components, and only one patient had a cystic tumor. However, the only patient who had a pure cystic tumor was affected with familial adenomatous polyposis (FAP). We herein report an extremely rare case of a sporadic desmoid tumor involving the pancreatic tail, presenting as a cystic lesion. To our knowledge, this is the first reported case of a “sporadic” desmoid tumor involving the pancreas, presenting as a pure cystic lesion. Correspondence Author to: Chi-Kuang Liu Department of Medical Imaging, Changhua Christian Hospital, Changhua, Taiwan No. 135, Nan-Xiao Street, Changhua 500, Taiwan J Radiol Sci 2014; 39: 91-95 Desmoid mimicking cystic pancreatic lesion 92 J Radiol Sci September 2014 Vol.39 No.3 administration, the lesion showed mural enhancement. The spleen was not involved in the tumor, but the splenic artery and vein were compressed by the lesion. Besides, the lesion also showed an indistinct margin to the stomach. Owing to the imaging characteristics, a pancreatic mucinous cystadenoma or pseudocyst was suspected initially. The patient received surgical treatment and the operation proceeded smoothly without immediate complications. On gross examination (Fig. 3a), there was a soft tissue tumor measuring 7.5×6.6 cm2 in dimension with pancreas involvement. The tumor had a gray-white and firm cut surface. There was a unilocular and well-demarcated cystic lesion measuring 7.5×6.6 cm2 with green brownish watery fluids within the part of the pancreas involving the tumor. No papillary or solid component was observed on the cystic wall. Microscopically (Fig. 3b), the tumor comprised elongated, slender, spindle-shaped cells of a uniform appearance arranged in interlacing fascicles and focal storiforms separated by collagen bundles infiltrating into the pancreatic parenchyma. Immunohistochemical studies of the tumor cells showed β-catenin (+), ALK (-), CD34 (-), p53 (-), and Figure 2