Distinguishing prostatic from colorectal adenocarcinoma on biopsy samples: the role of morphology and immunohistochemistry.
BACKGROUND
Poorly differentiated carcinoma on prostate or colorectal biopsy can occasionally present a diagnostic challenge in determining tumor source especially in locally advanced colorectal carcinoma (CRCa) or prostate carcinoma (PCa). Such determination can affect prognosis and therapy.


OBJECTIVE
To evaluate the role of morphology and immunohistochemistry in the previously mentioned setting.


METHODS
Surgical pathology and consultation records. Hematoxylin-eosin sections were reviewed in 16 cases (11 PCa, 5 CRCa). Immunohistochemistry for 9 markers was performed in 15 cases.


RESULTS
Dirty necrosis, seen in 5 (100%) of 5 CRCa and 2 (18%) of 11 PCa cases, and the presence of columnar cells with basal nuclei, seen in 5 (100%) of 5 CRCa and 1 (9%) of 11 PCa cases, appear to be the most useful morphologic parameters. Immunohistochemistry confirmed the value of prostate-specific antigen (PSA), CDX2, cytokeratin (CK) 20, and beta-catenin in the differential of CRCa (0% PSA+, 60% CDX2+, 80% CK20+, and 100% beta-catenin+) versus PCa (80% PSA+, 0% CDX2+, 10% CK20+, and 0% beta-catenin+). P501S had a similar sensitivity as PSA in detecting PCa (80%). Two (20%) of 10 PCa cases were positive for 1 of the 2 markers but not the other. P501S was negative in all 5 cases of CRCa.


CONCLUSIONS
P501S is a useful marker in this setting when included together with PSA, CDX2, CK20, and beta-catenin. P501S labels a subset of PCa cases that are negative for PSA. Dirty necrosis and/or columnar cells with basal nuclei could also be of help.
Owens
Christopher L
CL
Department of Pathology, The Johns Hopkins Hospital, Baltimore, MD, USA.
Epstein
Jonathan I
JI
Netto
George J
GJ
D000230:Adenocarcinoma / Q000378:metabolism / Q000473:pathology*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000032:analysis*; D000071616:CDX2 Transcription Factor; D015179:Colorectal Neoplasms / Q000378:metabolism / Q000473:pathology*; D003937:Diagnosis, Differential; D018398:Homeodomain Proteins / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D053554:Keratin-20 / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D017430:Prostate-Specific Antigen / Q000378:metabolism; D011471:Prostatic Neoplasms / Q000378:metabolism / Q000473:pathology*; D012680:Sensitivity and Specificity; D051176:beta Catenin / Q000378:metabolism
D014408:Biomarkers, Tumor; D000071616:CDX2 Transcription Factor; C491270:CDX2 protein, human; D018398:Homeodomain Proteins; D053554:Keratin-20; D051176:beta Catenin; D017430:Prostate-Specific Antigen