The purpose for this page is to provide first approach to pancreatic cytology through use of images and brief explanatory text. I recommend specific reading & scientific articles for more detailed information about pancreatic cytopathology.
I tried to organize the page starting with normal cytology, go ahead with cystic e mucus-producing neoplasm, adenocarcinoma (& its main variants) and finally endocrine tumors category. Mesenchymal tumors & metastases are not treated.
All images shown are part of my private collection, hope you enjoy.
They appear as variably-sized cohesive groups of cells, sometimes with central lumen (Fig.1). Individual cells are with granular cytoplasm, round nuclei and fine granular chromatin(Fig.2).
They appear as two-dimensional sheet of cells with a “honeycomb” pattern. Individual cells appear bland with scant cytoplasm and small, round to oval nuclei and fine granular chromatin (Fig 3-4). The reactive epithelium con show a variable degree of atypia that can overlap with that of malignancy; one should be wary of making a unequivocal diagnosis of malignancy based only on the presence of a few atypical cells or with slight atypical features (Fig 5).
When evaluating pancreatic FNA, it is important to have knowledge of how the specimens are obtained as the cell types of contaminants encountered varies with the different approaches:
- liver – percutaneous: polygonal cells, well defined cytoplasm, cytoplasmic pigments (A)
- gastric mucosa – endoscopic FNA for lesions in the body & tail: two dimensional flat sheet with orderly honeycomb arrangement, pale cytoplasm with well defined border, round evenly spaced and bland-appearing nuclei (B-C)
- duodenal mucosa – endoscopic FNA for lesions in the head & uncinate: two dimensional flat sheet with orderly honeycomb arrangement, scant cytoplasm, round evenly spaced and bland-appearing nuclei, intermixed goblet cells (D)
They are cavities within the pancreas that result from lysis of the tissue after leakage of pancreatic enzymes. This type of cyst lack epithelial lining and the cavities are filled with hystiocites, necrotic, hemorrhagic and inflammatory debris (Fig.6).
Aspirates usually show clear fluid with small sheets of cuboidal, bland glandular cells without atypical features (Fig.7-8).
Cystic Mucus-producing neoplasia – IPMN & Mucinous cystic neoplasm
The cytological features, such as cellularity and the degree of atypia largely depend on the cytologic grade of the lesions. Aspirates are all charaterized by the presence of mucoid backgruond (Fig.9). Low grade lesions tend to be less cellular and the neoplastic cells may demonstrate minimal atypia and be difficult to distinguish from contaminant gastrointestinal epithelium. High-grade lesions tend to be more cellular, demonstrate more conspicuous cytologic atypia and are more likely to show necrotic debris in to the cystic cavity (Fig.10 to 12).
Solid Pseudopapillary Tumor
Highly cellular aspirates composed by cells arranged in branching papillary fronds (also known as “Chinese calligraphy pattern” Fig.13) with fibro-vascular core (Fig.14), scant cytoplasm, monotonous and bland appearing round shaped nuclei, without significant atypia (Fig.15).
Aspirates of ductal adenocarcinoma are ofted highly cellular. The background can be clean, necrotic, inflammatory, mucinous or cystic. Neoplastic ductal cells are arranged in groups and form sheets, clusters, and three-dimensional aggregates. Within the cell groups, the cells are often overcrowded and arranged in hapazhard fashion. Variable numbers of isolated, atypical cells are also seen often identificated. Some degrees of nuclear pleomorphism and atypia are always present (Fig.16 to 21) but can be quite subtle in cases of well differentiated adenocarcinoma (Fig.22).
Some of the main variants of adenocarcinoma
- Foamy gland adenocarcinoma: Cells with abundant foamy cytoplasm (Fig.23)
- Signet ring adenocarcinoma: Cells with large cytoplasmic vacuoles (occasionally thickened mucus containing) that sometimes push atypical nuclei to the periphery (Fig.24)
- Adenosquamous carcinoma: Presence of both malignant glandular and squamous component (Fig.25). Sometimes the squamous component may prevail, but primary squamous cells carcinoma of the pancreas is a very rare entity.
Typical cytological features of pancreatic endocrine tumors are: cellular aspirates, loosely cohesive cell groups, rosette or pseudorosette formation(Fig.26), relatively uniform, round-to-polygonal tumor cells, plasmacytoid cells, salt & pepper chromatin pattern (Fig.27 to 29)
Immunohistochemistry (images are from cytoblock (Fig 30-A)) shows rectivity for Cromogranin (Fig.30-B), Synaptofisin (Fig.30-C), CD56; proliferation index (Ki67-Mib1 (Fig.30-D)) depend on the cytologic grade of the lesions. Low-grade lesions tends to have low proliferation index.