Solid‐pseudopapillary neoplasm of the pancreas: Awareness of unusual clinical presentations and morphology of the clear cell variant can prevent diagnostic errors

Abstract

Solid-pseudopapillary neoplasm (SPN) of the pancreas is a rare neoplasm predominantly reported in young women. It classically presents as a large tumor with cystic and solid components. The major differential diagnosis includes pancreatic neuroendocrine tumor (PanNET). This study presents our experience with this tumor with emphasis on the morphologic features of the clear cell variant of SPN. Fifteen histologically confirmed SPN were identified in our files. Endoscopic ultrasound-guided fine needle aspirations (EUS-guided FNA) were performed in 8/15 cases. Patients' demographics, cytohistologic correlation and tumor characteristics were evaluated. Eleven of the 15 subjects were female and four were male with an age range of 17-73 years. Twelve SPN were located in the pancreatic body/tail, and three in the head. Tumor size ranged from 1.5 to 8.5 cm and 11 were solid. Of the eight EUS-guided FNA, four were diagnosed as SPN, two as SPN vs. PanNET, one as malignant with signet ring features, and one was nondiagnostic. Immunohistochemistry was performed on six/eight FNA cell blocks and 13/15 surgical specimens. Two of the 15 cases were classified as clear cell variants of SPN. Our study shows that SPN may occur in males and older adults, and present as a small or solid tumor. The clear cell variant of SPN, characterized by vacuolated cytoplasm and signet cell morphology, may pose a diagnostic challenge on FNA. Awareness of the wide spectrum of SPN clinical presentations, the morphology of its clear cell variant and the appropriate use of ancillary immunohistochemistry can prevent diagnostic errors.

Hyaline globules and papillary fragments in cytologic smears from two intra‐abdominal tumors (ovarian and hepatic) in female patients: A diagnostic pitfall with histologic correlation

“…The present study describes the cytological findings with histologic correlation of two tumors that can appear predominantly in young woman and share some cytologic and histologic similarities such as: papillary pattern, hyaline globules and intercellular basement membrane deposits …”

“…Solid pseudopapillary neoplasm of the pancreas (SPNP) is an infrequent tumor reported to account for <3% of all non‐endocrine pancreatic tumors . It frequently appears in young women, and due to its rare aggressive behavior it should be differentiated from other highly metastatic pancreatic neoplasms …”

Clear cell variant of solid pseudopapillary neoplasm of pancreas diagnosed by fine needle aspiration: A case report and review of the literature

“…[134567] We present the cytologic features of clear cell variant of SPN with the broad differential diagnosis and a review of past studies.…”

Solid-pseudopapillary neoplasm of the pancreas – comparisons between magnetic resonance and histological findings

“…In differential diagnosis acinar cell carcinoma, pancreatoblastoma, neuroendocrine neoplasms, metastatic adenocarcinomas as well as non-neoplastic lesions such as post-inflammatory pseudocyst, parasitic cyst or ectopic spleen also have to be included [4]. Characteristic cytological and histological features of the tumor are usually sufficient for diagnosis (Table I) [12,13], but some variants with less typical morphology are a diagnostic challenge [14]. In such cases a panel of antibodies is helpful, although overlapping of some immunohistochemical reactions among pancreatic neoplasms is well known (Table I).…”

“…Generally, it could be performed using traditional histological staining methods but immunohistochemical reactions have to be applied especially in lesions with cellular pleomorphism, high mitotic activity, vessel invasion or metastases without known location of primary tumor [4,14]. In such cases components of sarcomatoid or undifferentiated carcinoma could be occasionally revealed.…”