Uterine diffuse adenomatoid tumor. Does it represent a different biological entity?

Adenomatoid tumor represents a type of mesothelioma apparently confined to the genital tract and characterized by its benign behavior. Its morphological aspects are well known and, until now, it has been described as a nodular mass except for a case diffusely infiltrating the entire myometrium in an immunosuppressed patient. We report a case of benign mesothelial tumor characterized by histological, immunophenotypical and ultrastructural features of an otherwise typical adenomatoid tumor but diffusely growing below uterine serosal surface into the myometrium without discernible borders. The existence of a diffuse type of adenomatoid tumor might reflect a different nature of this neoplasm leading to the hypothesis that this variant of benign mesothelioma represents a distinct biological entity.