title: Ductulo-insular pancreatic endocrine neoplasms: clinicopathologic analysis of a unique subtype of pancreatic endocrine neoplasms.
abstract: Pancreatic neoplasms with mixed ductal and endocrine components are a heterogeneous group of tumors. The least recognized of these are pancreatic endocrine tumors (PETs) displaying benign-appearing tumor-associated ductules. To characterize these ductulo-insular pancreatic endocrine tumors (DI-PETs), we reviewed a series of 92 resected PETs. To be considered as a DI-PET we required the presence and tight intermingling of ductules with the dominant endocrine component (including the presence of ductulo-insular units). A total of 15 PETs fulfilled our criteria (16.3%). The average age of the DI-PET patients was similar to typical PETs (54 years vs 56 years). These tumors were smaller and more often insulin positive than typical PETs (p <0.05). Diffuse stromal fibrosis was more frequent in DI-PETs (11 of 15; 73.3.7%) compared with PETs (8 of 72; 11.1%) (p <0.05). The tumor-associated ductules were composed of cuboidal cells with dense eosinophilic cytoplasm and round nuclei without atypia or mitoses. They were positive for cytokeratin 7 and cytokeratin 19 and lacked any neuroendocrine markers. Reversibly, the endocrine component was negative for cytokeratin 7 and cytokeratin 19 and positive for neuroendocrine markers. Ultrastructural examination of ductulo-insular units confirmed a dual ductal and endocrine differentiation with amphicrine differentiation in one case. Follow-up was available in 12 cases with an average follow-up of 70.1 months (range 25-203 months). Ten patients are currently alive, and two patients died 81 and 158 months after surgery. We conclude that DI-PETs are not uncommon and that they are biologically similar to other PETs. We also hypothesize that the ductal cells develop by transdifferentiation of the endocrine cells.
authors.affiliation: Department of Pathology, Massachusetts General Hospital, 55 Fruit Street, Boston, MA 02114, USA.
authors.forename: Vikram
authors.initials: V
authors.lastname: Deshpande
authors.forename: Martin K
authors.initials: MK
authors.lastname: Selig
authors.forename: Gunnlaugur Petur
authors.initials: GP
authors.lastname: Nielsen
authors.forename: Carlos
authors.initials: C
authors.lastname: Fernandez-del Castillo
authors.forename: Gregory Y
authors.initials: GY
authors.lastname: Lauwers
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018273:Carcinoma, Islet Cell / Q000145:classification / Q000453:epidemiology / Q000473:pathology*; D002648:Child; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007150:Immunohistochemistry; D015994:Incidence; D008297:Male; D008875:Middle Aged; D010190:Pancreatic Neoplasms / Q000145:classification / Q000453:epidemiology / Q000473:pathology*