Rectal Tissue In Prostate Biopsy Specimens Can Mimic Prostate Cancer

Rectal Tissue In Prostate Biopsy Specimens Can Mimic Prostate Cancer
Friday, 08 September 2006
BERKELEY, CA (UroToday.com) - Prostate biopsies, similar to other organ
biopsies involve placing the biopsy needle through other organs or
structures in order to obtain the desired study tissue.

Rectal tissue is commonly included with prostate biopsy specimens, and as
another glandular tissue, rectal tissue can be misdiagnosed as prostate
cancer (CaP).

Drs. Schowinsky and Epstein from the Johns Hopkins University School of
Medicine report histologic findings that occur in rectal tissue on
prostate biopsy specimens that mimic CaP. Their report appears in the July
2006 issue of the American Journal of Surgical Pathology.

A group of 16 biopsy specimens from 14 patients referred to the authors
between 1996 and 2005 were evaluated. In 15 of 16 biopsies (94%), rectal
glands were present only as a single focus. In 63%, the rectal glands were
present on detached fragments of tissue and in 1 case the glands were
involving adipose tissue at the end of a biopsy core. Blue mucin was
detected in 63% of rectal glands, and is seen in approximately 33% of
prostate biopsies with minimal cancer. Goblet cells were noted in 44% of
cases and elements of loose connective tissue consistent with lamina
propria were found in 75% of cases.

At a cellular level, mitotic activity was noted in 37% and prominent
nucleoli were seen in 37%. Inflammation was found in 63% of cases. A
triple immunoperoxidase stain for p63, high molecular weight cytokeratin
(HMWCK) and -methylacyl-coA racemase (AMACR) was used in 4 cases as rectal
glands lack basal cells and thus stains for HMWCK and p63 should be
negative. In 3 cases, p63 and HMWCK were negative and AMACR was positive.
This is likely due to the fact that AMACR is positive in over 70% of
rectal tissue. In the 4th case all three stains were negative.

The excellent photographs in this manuscript illustrate the descriptions
of the histologic features. In general, rectal glands on prostate biopsy
tend to be in detached fragments or at the end of a core sample, in a
single focus and associated with loose connective tissue consistent with
lamina propria.

Am J Surg Pathol 2006;30:866-70


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