[367] Dual CK5/P63 Staining in Pulmonary Squamous Cell Carcinoma: Utility in Cell Blocks.

Nazneen Fatima, Cynthia Cohen, Momin T Siddiqui. Emory University Hospital, Atlanta, GA

Background: Squamous cell carcinoma (SQCC) is the second most common type of lung cancer, constituting about 30% of lung cancers. Increasing demand for accurate differentiation of SQCC from other subtypes can be challenging for pathologists. This is more so in fine needle aspirations (FNA) since SQCC may show degenerative changes which can be perceived as cytoplasmic vacuoles with abortive lumen formation. Immunohistochemistry (IHC) is a valuable adjunct in the sub-classification of non small cell lung carcinoma. Stains used for this purpose include TTF-1, CK7, CK20, P63 and CK5/6, with, immunoreactivity for p63 and/or CK5/6 basically restricted to SQCC. The combination of these two stains has been reported to have a high reliability for diagnosing SQCC of the lung.
Design: To evaluate the utility of this dual stain, we studied FNA cell blocks (CB) of 24 SQCC and 34 adenocarcinoma (ADC) of the lung. Dual CK5/P63 IHC was performed. Red CK5 cytoplasmic stain and brown P63 nuclear stain was examined. For positive control, a histologic section of a primary lung SQCC was used.

Table 1:
Dual CK5/P6317/24 (70%)0/34 (0%)
P63 Component Alone2/24 (8%)3/34 (8%)
CK5 Component Alone2/24 (8%)0/34 (0%)

Table 2
Dual CK5/P63 Stain in SQCC70%100%88%100%

Conclusions: Cytologic evaluation with dual staining for CK5/P63 has a high sensitivity and specificity for diagnosing lung SQCC. This dual stain can distinguish SQCC from ADC with an accuracy of 88% and a positive predictive value of 100%, which is extremely critical for diagnostic and therapeutic decisions.
Category: Cytopathology

Monday, February 28, 2011 9:30 AM

Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 54, Monday Morning


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