Maspin expression patterns differ in the invasive versus lepidic growth pattern of pulmonary adenocarcinoma.

To test whether changes in the subcellular localization of maspin parallel morphological progression in pulmonary adenocarcinoma, we compared its expression between lepidic and invasive growth patterns. Applying immunohistochemistry, we compared maspin expression in lepidic and invasive growth patterns occurring in different tumours (series #1, n = 86) as well as within the same tumour and in the same section (series #2, n = 29). In both series, the lepidic growth pattern (n = 45) was significantly associated with nuclear maspin, while the invasive (n = 70) with combined nuclear and cytoplasmic maspin (P < 0.05). In the second series, transition from a lepidic to an invasive pattern in the same tumour was associated predominantly with a shift respectively from a nuclear to a combined nuclear and cytoplasmic maspin (15/29) or preservation of nuclear expression (8/29). A shift from nuclear maspin to negative expression (3/29) or other patterns (3/29) were also observed. Nuclear maspin is a typical but not exclusive feature of the lepidic growth pattern of pulmonary adenocarcinoma, whereas combined nuclear and cytoplasmic maspin characterizes invasion. These data show that changes of expression and subcellular localization of maspin may constitute an important biological end point of tumour progression and aid in the classification of lung adenocarcinoma.