Idiopathic Abdominal Wall Endometrioma: Case Report with Investigation of the Pathological, Molecular Cytogenetic and Cell Growth Features In Vitro.

Abdominal wall endometriosis (AWE) is a clinical disorder with unknown pathogenesis with an incidence between 0.03% and 1% in women affected by cutaneous/scar endometriosis. We investigated the pathological, molecular cytogenetic and cell proliferation features of a primary AWE developed in rectus abdominis muscle in a patient without co-existing pelvic endometriosis. An investigational model of cultured stromal cells was additionally established. Histologically, the lesion revealed areas of endometrial-like glands surrounded by a thick stromal layer in addition to numerous disseminated foci composed exclusively of stromal cells. Beyond the strong expression of Estrogen (ER) and Progesterone receptors (PRs), consistent immunolabeling for several mesenchymal stromal/stem cell antigens and oncoproteins was revealed in both the endometrioma as well as in the cultured stromal cells. The Fluorescence in situ hybridization (FISH) analysis of the endometrioma demonstrated a structural alteration of the c-MYC protooncogene, with a mean of three gene copies in 3% to 5% of both glandular and stromal cells. The FISH assay applied on the cultured cells showed c-MYC gene amplification, with an average number of more than six gene copies in 18% to 25% of the cellular nuclei. Altogether, these results markedly highlight the pathological and molecular features of idiopathic AWE essential for histo-pathogenetic categorization.