Category

Histologic Features

PanIN-1A

Flat epithelium composed of tall columnar, mucin producing cells with basally located, small nuclei

PanIN-1B

Papillary, micropapillary mucinous metaplasia or basally pseudostratified architecture

PanIN-2

Nuclear changes: pseudostratification, crowding, hyperchromasia, enlargement, Nuclei = 20 um, obviously pleomorphism. Flat to papillary proliferations

PanIN-3

Predominately papillary or micropapillary architecture, cribiforming and luminal necrosis.

severe atypia: loss of polarity, dystrophic goblet cells, large cells, enlarged, irregular nuclei and prominent nucleoli and mitotic figures (some abnormal)

Classification

Diagnosis

Histologic Features

Low Grade

Adenoma with low grade dysplasia

Single layer of uniform cells with well-oriented small uniform nuclei; nuclear stratification mainly in lower half of epithelial lining; well-maintained polarity; no prominent nucleoli; uniform nuclear change with rare nucleoli and mitoses

Intermediate

Adenoma with intermediate dysplasia

nuclear stratification mainly in lower half of epithelial lining, nuclear crowding, nuclear hyperchromatism; high N:C ratio, some loss of polarity, nuclear enlargement and pleomorphism; papillae retain fibrovascular cores.

High Grade

Carcinoma in-situ

Papillary or micropapillary without fibrous core, areas of cribriform growth and budding of small clusters of epithelium into the lumen; loss of polarity, decreased mucin, cellular and nuclear pleomorphism, nuclear enlargement and mitoses (suprabasal)

Invasive carcinoma

Stromal desmoplasia, irregular glandular out-contour, irregular small cell clusters in stroma, incomplete glandular lumen. Marked nuclear pleomorphism (nuclear size varies > 4 times) may be seen.