Pancreatic Pathology Online
An Approach to Macroscopic Assessment of Pancreatic Specimen
Correct orientation of the specimen is crucial and in the case of Whipple’s specimens this is aided by identification of the gastric, duodenal, pancreatic and bile duct surgical margins.
It is useful to remember that the common bile duct enters the superior border of the pancreas just below the distal greater gastric curvature and close to the posterior plane of the specimen.
A portion of superior mesenteric vein wall may be adherent to the anterior aspect of the specimen.
Initial specimen preparation:
- The type of specimen should be recorded.
- Where applicable, the length of the gastric and duodenal components, the pancreas and the extrapancreatic common bile duct should be recorded.
- The presence and size of any omental or mesenteric tissue should be noted.
- The stomach (if present) and duodenum should be opened and cleaned, making sure that the latter is incised along the border opposite to the pancreas. The pancreas may also be incised at this stage .
- The specimen can then be pinned to a cork mat and left for further formalin fixation for at least 24 hours.
Pancreaticoduodenectomy (Whipple’s specimens)
Marking of resection margins:
- The anterior peritoneal surface of the pancreas, retroperitoneal surgical margin and superior mesenteric vein surgical margin should be marked with different colors of ink.
- Careful drying of the specimen is essential before applying the ink, to minimize color mixing and potential future confusion over margins.
- Specimens marking may be performed before or after further formalin fixation, but inking of all margins is strongly recommended prior to incision of the pancreas.
The pancreatic surgical margin will often have been taken already as a frozen section but may alternatively be sampled at this stage.
Opinion is varied regarding the optimum method of incising the pancreas but the key is to be able clearly to demonstrate:
(1) the lesion and ; (2) the surgical margins.
- The most commonly used method involves making a series of parallel incisions through the pancreas in the horizontal plane, usually extending the incision through the adjacent duodenum.
- One of the incisions may be made through the ampulla of Vater if a lesion is present in this area.
- However, lesions sited primarily within the lower common bile duct may be best demonstrated via one or more incisions in the coronal plane.
- Whichever technique is used, it is often useful to pass a metal probe through the ampulla of Vater or common bile duct as a guide when choosing the position of first incision, particularly when visualization of one or both of these structures are required.
- The incision may alternatively be made prior to further formalin fixation, but care must be taken not to disrupt the surgical margins.
- The maximum diameter of any lesion should now be recorded as well as an estimation of its distance from the main surgical margins.
- The number of blocks taken will vary with the nature of the lesion.
- However, a general guide would be to take at least three blocks of any lesion to include the inked surgical margins, together with the common bile duct margin and pancreatic surgical margin if not separately sampled.
- If segmental excision of the superior mesenteric vein has been performed, its margin should also be sampled.
- Large, cystic and multicentric lesions will require more extensive sampling and a rate of one block per 1-2 cm of lesion diameter is recommended.
- Most pancreatic lesions, apart from some cystadenomas and intraduct proliferations, will be unicentric in nature.
- Representative sections should be taken from the distant pancreas, stomach, duodenum and gallbladder to exclude background abnormality.
- Usually the section that is macroscopically most representative is taken as a large block.
- This is not essential but, especially if taken in the horizontal plane, facilitate correlation of the histopathological and CT scan appearances.
- The major regional lymph node groups will require dissection from the main specimen unless received separately.
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