Significance of stromal markers in atypical polypoid adenomyoma

Atypical polypoid adenomyoma (APA) may progress to endometrioid carcinoma and may mimic myoinvasive carcinoma on biopsy specimens. Here, we present a case of an APA of the uterine cervix hysteroscopically treated, which recurred two years after and progressed to endometrioid carcinoma. In all biopsy specimens and in the hysterectomy specimen, the benign APA component showed an unusual immunohistochemical stromal pattern (periglandular fringe-like CD10 pattern, diffuse h-caldesmon positivity, p16 negativity), which is typical of myoinvasive carcinoma. Interestingly, the other three cases of cancerized APA assessed for h-caldesmon in the literature showed diffuse stromal positivity also in the benign APA component. Our case shows that the stromal markers used for differentiating between APA and myoinvasive carcinoma may be misleading even when their pattern seems unequivocal. Furthermore, our case suggests that h-caldesmon positivity might be a prognostic marker for progression of APA to carcinoma. Further studies are encouraged in this regard.