Clinical history: A 39 y/o female c/o uterine bleeding
What is your diagnosis?
Discussion and answer
Sections of endomyometrium show a polypoid solid mass attached to the endometrium by a narrow stalk. The mass is characterized by inconspicuous endometrial glands admixed with extensive squamous morules and a cellular myofibromatous stroma. Overall, the mass has an intertwining spindled appearance. The epithelial component shows moderate cytological atypia and numerous mitotic figures. The stromal component consists of small branching bundles of cellular myofibroblasts/smooth muscle.
There is NO invasion into the stalk of the lesion, the underlying anterior wall myometrium, or the posterior wall myometrium. There is no vascular space invasion. Immunohistochemical staining has been performed and shows strong immunoreactivity in the mixed glandular and spindled morular areas with AE1/3, vimentin, ER and PR. Immunohistochemical staining for SMA demonstrates nicely the presence of the smooth muscle bundles scattered throughout the neoplasm. Mib-1 is positive in more than 50% of the neoplastic epithelial cells, in keeping with the mitoses noted in the H&E stained sections. Based on the morphology and immunohistochemical staining profile, this lesion is most consistent with an atypical polypoid adenomyofibroma (atypical polypoid adenomyoma).
APA is a benign neoplasm which often occurs in lower uterine segment in young women. It is usually rich in estrogen and progesterone receptors. APA of low malignant potential, as originally described, can show limited myometrial invasion and a tendency to recur locally at the site of original resection in the uterus when the lesion has been treated conservatively by hysteroscopic resection or curettage. Total hysterectomy, as performed in this case, is the definitive treatment.
Reference: Longacre TA, et al. Atypical polypoid adenomyofibromas (atypical polypoid adenomyomas) of the uterus. A clinicopathologic study of 55 cases. Am J Surg Pathol 1996 Jan; 20 (1): 1 – 20.