Desmoglein 3 (DSG3) is a calcium-binding
transmembrane glycoprotein component of desmosomes in vertebrate epithelial
cells. Studies have shown DSG3 to have 83-95% sensitivity and 100% specificity
in detecting squamous cell carcinoma (SqCC) vs. lung adenocarcinoma. DSG3 is
associated with shorter survival for all lung cancer patients regardless of the
histologic subtype (5-year survival of 20.9% vs. 49.5%, P < .001). Patients
with atypical carcinoid tumors, lacking Desmoglein 3 expression showed a 5-year
survival of 0% compared with 36.8% for DSG3 positive cases (P <
.001).
Napsin A is expressed in type II
pneumocytes of normal lung and in adenocarcinomas of the lung and kidney.
Studies have shown that Napsin A is more sensitive (80-87%) and more specific
marker than TTF-1. Napsin A is 100% specific for lung adenocarcinoma vs. 100%
negative in lung SqCC. Napsin A used in combination with TTF-1 provides 93%
sensitivity and 100% specificity for lung adenocarcinoma, if CK5 and Desmoglein
3 are both negative in the same section.
DSG3 is a cell membrane stain that marks
lung SqCC (DAB). Napsin A is a cytoplasmic/granular stain that marks lung
adenocarcinomas (Fast Red). In the vast majority of lung cancers tested, only a
single antibody stain will be observed. Coexpression of both antibodies may be
observed in adenosquamous cell carcinomas, or in some cases residual normal lung
will stain with Napsin A. Desmoglein 3 + Napsin A are very sensitive and
specific markers for discriminating between lung SqCC and lung adenocarcinoma.
This antibody combination is extremely accurate and is 100% specific. In grades
1-2, Desmoglein 3 + Napsin A provide staining sensitivity in the mid 90% range;
thus the antibody combination of Desmoglein 3 + Napsin A is a first-line
screener for discriminating between lung adenocarcinoma vs. lung
SqCC.