Diagnostic value of immunohistochemical panel (Cytokeratin CK 7, Cytokeratin CK20, High molecular weight cytokeratin HMWCK (clone CK34βE12) and Prostatic specific antigen (PSA) in differentiation between poorly differentiated prostatic and urothelial carc

Abstract

Background: Prostatic adenocarcinoma may spread to bladder or vice versa, this is because of the anatomical proximity of
these two organs. The differentiation between these two tumors is critical for therapeutic and prognostic implication.
Aim of study: Evaluate the usefulness of a panel of immunohistochemical markers (CK7, CK20, HMWCK34 βE12 and
PSA) in differentiation between challenging cases of high grade urothelial and poorly differentiated prostatic carcinoma with
morphological overlapping.
Material and methods: A total of 40 cases (20 cases poorly differentiated prostatic adenocarcinoma and 20 cases high grade
urothelial carcinoma) were collected from archive of teaching laboratory of Al Yarmouk teaching hospital and private laboratories
for the period from January 2015 to July 2017.All formalin fixed paraffin embedded tissue block were stained immunohistochemically
with a panel of marker (CK7, CK20, HMWCK34 βE12 and PSA) and scoring was performed.
Results: For prostatic adenocarcinoma, 17 out 20 (85%) were positive for PSA, while only two cases (10%) of urothelial carcinoma
cases showed weak and focal staining for this marker (the pvalue was <0.0001). In contrast, 16 out of 20(80%) of the
urothelial carcinoma cases were positive for CK34βE12 in comparison to only one case (5%)of prostatic carcinoma showed
positive expression for this marker (the p value was highly significant <0.0001).
Regarding CK7and CK20: combined expression of both markers was noticed in 17 cases (85%) of urothelial carcinoma
compared to only 2 cases(10%) of prostatic adenocarcinoma and the difference was highly significant(p value <0.0001). negative
expression for both markers was noticed in 18 cases (90%) of prostatic adenocarcinoma compared to only 2 cases (10%)
of urothelial carcinoma and the difference was highly significant( p value < 0.0001).CK7 positivity alone was noted in 17
cases(85%) of urothelial carcinoma while only 2 cases (10%) of prostatic carcinoma show positivity for this marker and the p
value was highly significant (p value < 0.0001).18 cases (90%) of urothelial carcinoma showed positive expression for CK20
alone compared to only to 3 cases (15%) of prostatic carcinoma (p value < 0.0001).
Conclusion: Using CK7 or CK20 alone will not be helpful for differentiation between prostatic carcinoma and high grade
urothelial carcinoma, while combined expression of both markers(CK7 and CK20) is very useful in ruling out carcinoma of
the prostate, since, it is very rare for both markers to show positive expression in prostatic carcinoma.In difficult cases that
show negative expression of both marker, CK34βE12 remain the most valuable marker for urothelial origin while, PSA immunohistochemical
marker remains the most helpful marker to prove the prostatic origin of metastatic carcinoma.