Solid Pseudopapillary Neoplasms of the Pancreas: Evaluation of Diagnostic Utility of Endoscopic Ultrasound-Guided Fine Needle Aspiration (EUS-FNA)

Abstract

Endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) is an important and accurate modality for the diagnosis of solid and cystic lesions of the pancreas. The objectives of this retrospective study are to review the pertinent cytologic criteria for diagnosing SPNs and to evaluate the diagnostic utility of EUS-FNA. A total of 924 pancreatic FNAs were performed at our institution from January 2002 through February 2013. Of these, four cases (three females, mean age 17 years; one male, age 61 years) were identified with a diagnosis of SPN initially rendered on cytologic material obtained by EUS-FNA and subsequently confirmed by histopathologic examination of the resection specimen. No on site evaluation was conducted for any of these cases. Cytologic smears were assessed by two independent reviewers for the presence of the following diagnostic features: a highly cellular aspirate; the presence of myxoid or hyalinized fibrovascular stalks lined by neoplastic cells with pale to finely granular cytoplasm and indistinct cell borders; and monotonous, round to oval nuclei containing delicate granular nuclear chromatin, inconspicuous nucleoli, and nuclear grooves and inclusions. Cell block material was available for confirmatory immunohistochemical studies in one case. Three of the four cases were diagnosed as SPNs, and one was deemed to be a pancreatic endocrine neoplasm (islet cell tumor) on cytologic evaluation. Of the remaining three cases determined to be a SPN on cytology, two were confirmed histologically by review of available slides obtained from the surgical resection specimens. The most consistent cytologic features for diagnosing SPNs by EUS-FNA in our series was the presence of a highly cellular aspirate containing several hyalinized fibrovascular stalks lined by monotonous neoplastic cells with round to oval nuclei and nuclear grooves. We conclude that EUS-FNA is an accurate and effective diagnostic tool in the diagnosis of SPNs of the pancreas.

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 case presented liver metastasis and the previous history of SPNP diagnosis prompt us to suggest a metastasis of the previously resected SPNP. In addition, the smear revealed several of the findings described in SPNP including: numerous papillary tissue fragments, hyaline globules, typical nuclear features with round to oval nuclei with indentations/grooves, occasional long cytoplasmic tails (cercariform cells) and the presence of basement membrane–like extracellular material . Although pseudorosettes were occasionally observed the nuclei did not reveal the fine (“salt‐and‐pepper”) chromatin observed in neuroendocrine tumor .…”

“…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 …”

“…Differentiating between metastasis from neuroendocrine tumors and SPNP may represent a diagnostic challenge. Although SPNP is frequently a solid and cystic neoplasm; it may also exhibit a solid pattern with occasional rosette formation mimicking a neuroendocrine tumor . Hyaline globules have typically been associated with SPNP, although they are not specific to these tumors, having occasionally been reported in neuroendocrine tumors .…”

“…YST may exhibit numerous histological patterns, including microcystic/reticular, glandular, endodermal sinus, papillary, alveolar‐glandular, macrocystic, hepatoid, polyvesicular vitelline, myxoid and uncommonly a solid configuration . 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 …”

“…Hyaline globules, papillary or pseudopapillary fragments and deposits of basement membrane material can be recognized by careful morphologic evaluation of the cytological smears in both YST and SPNP . Moreover, a new subtype of primary ovarian neoplasm with identical histological and immunohistochemical features of SPNP has recently been described; therefore the differential diagnosis of cytologic/histologic findings in some particular clinical setting is a challenge .…”