Estrogen and progesterone receptors expression in gastrointestinal stromal tumors and intramural gastrointestinal leiomyomas

Gastrointestinal stromal tumors (GISTs) and leiomyomas of the gastrointestinal tract both may present as intramural smooth muscle cell tumors. Immunohistochemically, these tumors demonstrate different spectrums of protein expression, which helps in differential diagnosis. Leiomyomas of the uterine type are similar by the spectrum of protein expression to gastrointestinal leiomyomas, but they express in addition both estrogen (ER) and progesterone (PR) receptors, which makes hormonal therapy possible for these tumors. In the current study, we investigated expression of ER and PR in GISTs and intramural gastrointestinal leiomyomas. Our data demonstrate that none of the 22 cases of gastrointestinal leiomyomas nor 19 cases of GIST were positive for either ER or PR expression. In contrast, leiomyomas of the uterine type were strongly positive for both ER and PR. Our data demonstrate that GIST and gastrointestinal leiomyomas differ from leiomyomas of the uterine type by the expression of ER and PR. Immunostaining for ER and PR may be a useful tool to distinguish these tumors and more precisely to plan further clinical interventions.