Aspiration cytopathology of peripancreatic space: A clinicoradiologic and cytopathologic analyses of 42 cases

Background: The pancreas is surrounded by soft tissue known as the peripancreatic space (PPS). Pathologic lesions of the PPS are infrequent and have only rarely been reported in the cytopathology literature. Methods: A retrospective review of cytopathology files at two large institutions revealed 42 cases of PPS lesions obtained by transabdominal fine needle aspiration (FNA) or endoscopic ultrasound-guided FNA over a 16-year period. Clinicoradiologic findings and follow-up information were also reviewed. Results: Patients ranged in age from 23-83 years (mean, 60 years) with an equal gender distribution. The major clinical presentations included pain, jaundice, nausea/ vomiting, and abnormal liver enzymes. Radiographic characteristics included lymphadenopathy and cystic/solid soft tissue masses with a size range of 1.5 to 8 cm. Cytologically, 4 (9.5%) cases were nondiagnostic, 9 (21.5%) were diagnosed as benign, 4 (9.5%) were atypical or suspicious for cancer, and 25 (59.5%) were malignant. Six of 25 (24%) patients had metastasis of a prior known malignancy. Conclusions: FNA of PPS masses is a rare occurrence. The majority of lesions are metastatic carcinomas from a variety of primary sites. Flow cytometry and immunoperoxidase studies are useful adjuncts to determine the tumor origin. The sensitivity of PPS aspiration for a malignant diagnosis is 90% with a positive predictive value of 100%.