Ultra thin needle histology may have impact in diagnosing chronic pancreatitis

Diagnosis of chronic pancreatitis is usually based on symptoms, ductal or parenchymal changes in imaging studies and function tests, but seldom on histology. Because the diagnosis of mild chronic pancreatitis is especially difficult, better tools to distinguish between chronic pancreatitis and normal pancreas are needed. Nowadays, cutting needles as thin as the widely used puncture needles are available. Using resected specimens, our aim was to evaluate whether these ultra-thin needles can take samples for histology that would allow verification of the diagnosis of chronic pancreatitis, with reference to a pancreatic wedge biopsy as the "gold standard".

Fifty patients underwent pancreatic resection for various reasons. Two 20 G needle biopsies (outer diameter 0.8 mm, study biopsies) and a 5 x 5-mm wedge biopsy (reference biopsies) were taken from the same site of the specimen, avoiding possible neoplastic areas in the specimen. The samples were analyzed for the presence inflammation and fibrosis, both graded 0-3, as well as for any neoplastic changes without knowledge of the medical history, operative findings or final histology.

The reference biopsy showed normal tissue in 19 (38%) patients, chronic pancreatitis in 29 (58%) and only mild fibrosis (Grade 1) in 2 (4%) patients. In one patient the needle biopsy was insufficient for analysis. There was agreement between ultra-thin needle histology and the control specimen in 45/49 (92%) patients (correlation coefficient 0.9). Two biopsies of chronic pancreatitis and one mild fibrosis were misclassified as normal tissue, while one chronic pancreatitis biopsy was misclassified as an adenocarcinoma. The sensitivity of needle biopsy for chronic pancreatitis was 89%, specificity 100% and accuracy 94%.

Ultra-thin needle histology correlates well with the pancreatic wedge biopsy. Thus, these encouraging results warrant further clinical studies of different grades and types of chronic pancreatitis.