The term leiomyo-adenomatoid tumor was originally used by Epstein to describe a type of adenomatoid tumor with prominent smooth muscle component . Adenomatoid tumor (AT) is an uncommon benign neoplasm described in both male and female genital tract but has occasionally been reported in other sites, such as mesentery, mediastinum, pleural cavity, adrenal gland, pancreas and heart . In uterus, adenomatoid tumor is generally seen subserosally near the cornua or within the outer part of the myometrium. These tumors usually occur as incidental findings in hysterectomy specimens and on occasion can be multiple. They are difficult to differentiate from leiomyomata on clinical examination, ultrasound, or magnetic resonance imaging .
On gross examination, these tumors range from 0.5-4 cm, tan-yellow in color and slightly less well circumscribed than typical leiomyoma. The cut surface may show whorled appearance, irregular fibrous trabeculae or small vesicles . A cystic variant has also been described . Microscopically, tumor shows adenoid, angiomatoid, solid, or cystic architecture. Most common architecture pattern is adenoid which on low power is characterized by small, often slitlike interconnecting spaces within the myometrium. An infiltrative pattern of tubules lined by cuboidal or attenuated epithelium is seen on higher magnification. Nuclear atypia, increased mitotic activity and stromal desmoplastic response are usually absent .
The histogenesis of adenomatoid tumor was debated. Recent studies suggest the tumor to be of mesothelial origin. The tumor cells are strongly positive for cytokeratin, vimentin, HBME-1 (anti-human mesothelioma antibody), and calretinin but negative for epithelial membrane antigen and carcinoembryonic antigen [3, 5]. Ultrastructural examination shows numerous apical microvilli, abundant cytoplasmic filaments, and desmosomes, which explains their strong keratin reactivity .
Contributed by Kavita Varma, MD