title: Importance of NAB2-STAT6 Fusion in the Diagnosis of Pancreatic Solitary Fibrous Tumor with Hamartoma-Like Features: A Case Report and Review of the Literature.
abstract: We report a case of pancreatic hamartoma-like solitary fibrous tumor which was differentiated from pancreatic hamartoma with the detection of NAB2-STAT6 fusion, a specific mutation for solitary fibrous tumors. A pancreatic well-demarcated solid nodule, 21 × 17 mm, of 82-year-old man was surgically enucleated. Microscopic findings were close to a pancreatic hamartoma that consisted of sparsely distributed pancreatic ducts and acini in heavily collagenized fibrous stroma. Neither islet nor peripheral nerve existed in the tumor. The fibroblastic cells in the stroma were immune-positive for CD34, CD99, and bcl-2. But these expressions were not decisive in the differentiation between solitary fibrous tumor and pancreatic hamartoma, because CD34 was positive for both tumors, and CD99 and bcl-2 expressions were not elucidated in the previous cases of pancreatic hamartomas. Thus, we evaluated NAB2-STAT6 fusion. The fibroblastic cells were positive for STAT6 and sequencing analysis revealed the gene fusion between NAB2 exon 4 and STAT6 exon 2, with which the final diagnos is of solitary fibrous tumor was achieved. In conclusion, detection of NAB2-STAT6 fusion has a great diagnostic value for pancreatic solitary fibrous tumors with hamartoma-like features.
authors.affiliation: Department of Surgery, Kensei General Hospital, 604 Kuwata, Sakuragawa, Ibaraki 309-1223, Japan ; General Surgery, Chiba University Graduate School of Medicine, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan.
authors.forename: Kei
authors.initials: K
authors.lastname: Tanaka
authors.affiliation: Department of Molecular Pathology, Chiba University Graduate School of Medicine, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Kishimoto
authors.affiliation: General Surgery, Chiba University Graduate School of Medicine, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Ohtsuka
authors.affiliation: Diagnostic Pathology, Chiba University Graduate School of Medicine, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan.
authors.forename: Yukio
authors.initials: Y
authors.lastname: Nakatani
authors.affiliation: General Surgery, Chiba University Graduate School of Medicine, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan.
authors.forename: Masaru
authors.initials: M
authors.lastname: Miyazaki