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Cancer Cytopathol. 2019 Nov;127(11):708-719. doi: 10.1002/cncy.22187. Epub 2019 Oct 3.

Pancreatoblastoma: Cytologic and histologic analysis of 12 adult cases reveals helpful criteria in their diagnosis and distinction from common mimics.

Author information

1
Department of Pathology, Emory University Hospital, Atlanta, Georgia.
2
Department of Biology, Georgia State University, Atlanta, Georgia.
3
Department of Pathology, Mayo Clinic, Rochester, Minnesota.
4
Department of Pathology, Memorial Sloan Kettering Cancer Center, New York, New York.
5
Department of Pathology, University of Michigan, Ann Harbor, Michigan.
6
Department of Pathology, Columbia University Medical Center, New York, New York.
7
Department of Pathology, Koç University Hospital, Istanbul, Turkey.

Abstract

BACKGROUND:

Pancreatoblastoma (PBL) is a rare malignant pancreatic tumor seen predominantly in childhood, and its cytologic diagnosis remains challenging.

METHODS:

Twelve fine-needle-aspirations from 11 adults were analyzed.

RESULTS:

In total, 6 men and 5 women (median age, 45 years; age range, 32-60 years) had tumors measuring a median 5.6 cm (range, 2.5-12 cm) located in the pancreatic head (n = 7) or tail (n = 4), including 3 with familial adenomatous polyposis (FAP)/FAP-related syndromes and 4 with metastasis at diagnosis. The median follow-up was 39.8 months (range, 0.8-348 months), and 5 patients died of disease. The original cytology diagnoses were: PBL (n = 2), neuroendocrine neoplasm (n = 2), poorly differentiated neuroendocrine carcinoma (n = 2), well differentiated neuroendocrine tumor (n = 1), poorly differentiated carcinoma (n = 2), "positive for malignancy" (n = 1), acinar cell carcinoma (n = 1), and epithelioid neoplasm with endocrine and acinar differentiation versus PBL (n = 1). Universal cytopathologic findings included hypercellularity; 3-dimensional clusters; and single, monotonous, blast-like cells that were from 1.5 to 2.0 times the size of red blood cells with high nuclear-to-cytoplasmic ratio, fine chromatin, small, distinct nucleoli, and a resemblance to well differentiated neuroendocrine tumor and poorly differentiated neuroendocrine carcinoma. Branching pseudopapillae (n = 7) and grooved nuclei (n = 3) raised the differential diagnosis of solid-pseudopapillary neoplasm, but with more atypia. Uncommon features included pleomorphism (n = 4) and numerous mitoses (n = 1). Squamoid morules were seen on smears (n = 5) or cell blocks (n = 6) in 70% of patients and were characterized by epithelioid cells with elongated, streaming nuclei, fine chromatin, absent nucleoli, and positive nuclear β-catenin (n = 6 of 8). The median Ki-67 index was 21% (range, 2%-70%), and neuroendocrine marker expression was common (100%), but acinar markers were variable (63%).

CONCLUSIONS:

A combination of cytologic findings in PBL, including a predominant population of primitive blast-like cells, subtle squamoid morules, frequent neuroendocrine and variable acinar phenotype, should facilitate accurate cytologic diagnosis and distinction from common mimics.

KEYWORDS:

cytology; fine-needle aspiration (FNA); pancreas; pancreatoblastoma

PMID:
31581358
DOI:
10.1002/cncy.22187

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