Carcinoma, Squamous Cell ; Epithelial Cells ; Humans ; Papilloma

OBJECTIVETo study the expression of squamous cell markers p63, p40 and CK5/6 in small cell carcinoma of lung (SCLC).

METHODSImmunohistochemical study for squamous cell markers (p63, p40 and CK5/6), neuroendocrine markers (chromogranin A, synaptophysin and CD56) and TTF1 was carried out in 283 cases of SCLC. The diagnostic value of these markers was evaluated.

RESULTSThe expression rate of p63, p40 and CK5/6 were 20.7% (54/261), 7.9% (5/63) and 0.5% (1/221), respectively in the cases of SCLC studied. Amongst the squamous cell markers, CK5/6 had the lowest rate of positivity (P < 0.01). On the other hand, chromogranin A, synaptophysin and CD56 were positive in 61.8% (170/275), 85.5% (242/283) and 89.2% (248/278), respectively. The positivity rate for chromogranin A was lower than that for synaptophysin and CD56 (P < 0.01). TTF1 was expressed in 77.2% (217/281).

CONCLUSIONSp63 and p40 are expressed in a subset of SCLC. In contrast, CK5/6 is rarely positive in SCLC. An immunohistochemical panel of CK5/6, synaptophysin and CD56 is recommended for differential diagnosis of SCLC.

CD56 Antigen ; genetics ; metabolism ; Chromogranin A ; genetics ; metabolism ; DNA-Binding Proteins ; genetics ; metabolism ; Diagnosis, Differential ; Humans ; Keratin-5 ; genetics ; metabolism ; Keratin-6 ; genetics ; metabolism ; Lung Neoplasms ; genetics ; metabolism ; Small Cell Lung Carcinoma ; genetics ; metabolism ; Synaptophysin ; genetics ; metabolism ; Transcription Factors ; genetics ; metabolism ; Tumor Suppressor Proteins ; genetics ; metabolism