Microcystic adenocarcinoma of the prostate-pseudobenign carcinoma

Reference :

Microcystic Adenocarcinoma of the Prostate: A Variant of Pseudohyperplastic and Atrophic Patterns : Yaskiv, Oksana et al.
The American Journal of Surgical Pathology: April 2010 - Volume 34 - Issue 4 - pp 556-561

Do you see anything in this prostate that's worrisome for malignancy?

dilated glands admixed with small acini in a nodule

I don't, at least not at this power, and yet this is an example of "microcystic" adenocarcinoma of the prostate. Higher power will show clear-cut cytologic features of malignancy.
If this doesn't concern you about the risk of scanning prostate slides at 4x, it should!

Microcystic adenocarcinoma with dilated and crowded glands displaying a predominantly flat lining layer

Microcystic adenocarcinoma with jumbled arrangement of dilated malignant glands.

Microcystic adenocarcinoma with atrophic features.

Dilated malignant glands with adjacent usual small acinar adenocarcinoma glands for size reference

Numerous crystalloids in dilated glands of microcystic adenocarcinoma.

Nuclear atypia with prominent nucleoli in the lining layer of 2 microcystic adenocarcinoma glands.

Microcystic adenocarcinoma extending into periprostatic adipose tissue, along with several small acinar adenocarcinoma glands.

Overerexpression of α-methylacyl CoA racemase in microcystic adenocarcinoma, with luminal accentuation. No basal cells are detected with this p63/AMACR cocktail immunohistochemical stain.

Overexpression of AMACR with granular cytoplasmic signal in microcystic adenocarcinoma gland with basal cell absence (right). Internal control benign atrophic glands on left show basal cell presence, with p63 marker, and lack of AMACR staining.

Basal cell absence in microcystic adenocarcinoma (left) compared with benign atrophic glands with basal cells (right), as assessed with 34βE12 immunostain.

Microcystic adenocarcinoma in needle biopsy tissue

Reference :

Microcystic Adenocarcinoma of the Prostate: A Variant of Pseudohyperplastic and Atrophic Patterns : Yaskiv, Oksana et al.The American Journal of Surgical Pathology: April 2010 - Volume 34 - Issue 4 - pp 556-561

Cystic glandular dilatation is a common finding in benign prostatic tissues, being identified in benign prostatic hyperplasia (BPH) in the transition zone and as cystic atrophy in the peripheral zone. Diagnostic awareness that acinar prostatic adenocarcinoma may exhibit cystic dilatation is important to avoid underdiagnosis of prostatic adenocarcinoma.

Cystic change in adenocarcinoma of the prostate is unusual and may be confused with benign cystic atrophy.Microcystic adenocarcinoma of the prostate is a distinctive histomorphologic presentation of prostatic adenocarcinoma that is deceptively benign-looking at low magnifications.

Detection of intraluminal crystalloids or wispy blue mucin at low magnification, immunostains for α-methylacyl CoA racemase, and basal cells, and a search for adjacent usual small acinar adenocarcinoma are helpful diagnostic aids. Diagnostic awareness of this growth pattern of prostatic carcinoma is important to avoid underdiagnosis of adenocarcinoma of the prostate.