The diagnostic utility of p63, CK5/6, CK 7, and CK 20 in distinguishing primary cutaneous adnexal neoplasms from metastatic carcinomas.
BACKGROUND
Distinguishing primary cutaneous adnexal neoplasms (PCANs) from metastatic carcinomas (MCs) can be difficult. We study the utility of p63, CK 5/6, CK 7, and 20 expression in PCAN vs. MC.


METHODS
Twenty-one PCAN with sweat gland differentiation (six benign, 15 malignant), one sebaceous carcinoma, and 15 MC (14 adenocarcinomas, one urothelial carcinoma) to skin were retrieved from the pathology files. Immunostains for p63, CK 5/6, CK 7, and CK 20 were performed and graded as follows: 1, <10; 2, 11-50; and 3 >50% of tumor cells stained.


RESULTS
Twenty of 22 PCAN expressed p63 and CK 5/6. Four of 15 and two of 15 MC were positive for CK 5/6 and p63, respectively. Thirteen of 22 PCAN and 13 of 15 MC were positive for CK 7, respectively. All PCAN were negative for CK 20, two of 15 MC were positive. The sensitivity and specificity for the diagnosis of PCAN were 91 and 73% for CK 5/6, 91 and 100% for p63, and 60 and 13% for CK 7, respectively.


CONCLUSIONS
For distinguishing PCAN from MC: (1) positivity for p63 and CK 5/6 are relatively specific and sensitive for PCAN, (2) CK 7 and 20 are neither sensitive nor specific, and (3) CK 7 positivity in PCAN was focal with a specific pattern in contrast to the diffuse positivity for MC.
Qureshi
Hina S
HS
Department of Pathology, Henry Ford Hospital, Detroit, MI, USA.
Ormsby
Adrian H
AH
Lee
Min W
MW
Zarbo
Richard J
RJ
Ma
Chan K
CK
D014408:Biomarkers, Tumor; D002277:Carcinoma / Q000737:chemistry / Q000175:diagnosis* / Q000556:secondary; D019084:Fluorescent Antibody Technique, Indirect; D006801:Humans; D007633:Keratins; D008565:Membrane Proteins; D018294:Neoplasms, Adnexal and Skin Appendage / Q000737:chemistry / Q000175:diagnosis*; D012189:Retrospective Studies; D012878:Skin Neoplasms / Q000737:chemistry / Q000175:diagnosis* / Q000556:secondary
D014408:Biomarkers, Tumor; C081876:CKAP4 protein, human; D008565:Membrane Proteins; D007633:Keratins