| The acinar epithelial cells are pseudostratified and arranged linearly in this example of flat variant of high-grade PIN. There is nuclear and nucleolar enlargement. Note the prominent apical snouts. |
High-grade PIN - Cribriform Pattern
In cribriform high-grade PIN interconnecting bridges of acinar epithelial cells extend across the lumen of the glands
High-grade PIN - Cribriform Pattern
Distinction of cribriform variant of high-grade PIN from adenocarcinoma may at times be extremely difficult. Immunostain for high molecular weight cytokeratin 34bE12 may be useful in such cases – basal cell layer is fragmented in PIN and absent in adenocarcinoma.
High-grade PIN - Tufted Pattern
Another example of tufted variant of high-grade PIN.
High-grade PIN & Cancer - 34bE12 Immunostain
The benign glands on upper right have continuous basal cell layer; high-grade PIN glands in the middle have fragmented basal cell layer; malignant glands on the left completely lack basal cell layer.
High-grade PIN - Prominent Nucleoli
This example of high-grade PIN shows all the classic histologic features: intermediate-to-large size preexisting glands displaying nuclear and nucleolar enlargement and fragmented basal cell layer.
High-grade PIN - Prominent Nucleoli
Another classic example of high-grade PIN, showing tufted and flat patterns.
High-grade PIN
High-grade PIN consists of intermediate to large size preexisting glands with proliferative changes resulting in hyperchromatic appearance. Note the small foci of cancer adjacent to PIN on the upper left and lower right.
High-grade PIN – Micropapillary Variant
he acinar epithelial cells are arranged in long, delicate, finger-like structures in this micropapillary variant. Atrophic acini are present at the bottom of the image.
Six variants of high-grade PIN have been described – tufted, micropapillary, flat, cribriform, small cell type, and the most recent addition – inverted type. The image depicts tufted variant. Note the enlarged nuclei, prominent nucleoli and residual basal cells.
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