Abstract

BACKGROUND
Absence of CD34-positive fibroblasts was reported within the stroma associated with invasive carcinomas. Conversely, tumor-associated desmoplastic stroma is characterized by the presence of smooth muscle actin (SMA)-reactive myofibroblasts. The present study was undertaken in order to elucidate whether the different distributions of stromal CD34-positive fibroblasts and SMA-reactive myofibroblasts are sensitive or specific markers of tumor invasion in small lung adenocarcinomas.
METHODS
Immunohistochemical stainings for CD34 and SMA were done in 37 peripheral adenocarcinomas less than 3.0 cm in diameter, including 16 adenocarcinomas with bronchioloalveolar carcinoma (BAC) and invasive components (mixed), and 21 invasive adenocarcinomas without BAC components (invasive).
RESULTS
The fibroblasts within the BAC components of the mixed group were mainly CD34-positive (81.2%) and preferentially SMA-negative (56.3%). In contrast, the fibroblasts within the invasive components of the mixed group were mainly CD34-negative (75.0%) and SMApositive (87.5%). The stromal cells of the invasive group were mostly negative for CD34 (90.5%) and positive for SMA (95.3%).
CONCLUSIONS
The loss of CD34 and the acquisition of SMA in the stromal cells within the tumor were related to tumor invasion (p<0.05). Thus, expression patterns of CD34 and SMA can be used to detect small foci of early stromal invasion in adenocarcinomas of the lung.

• Keywords: Antigens;CD34;Smooth muscle actin;Neoplasm invasiveness;Adenocarcinoma;Lung