Stromal melanocytic foci ("blue nevus") in step sections of the uterine cervix

Stromal melanocytic foci (SMF) of the uterine cervix, which are known as extracutaneous blue nevus, were examined in step sections of the cervix. A total of 189 uterine specimens surgically excised for leiomyoma, adenomyosis etc., were studied. The over-all incidence of SMF of the cervix was 28.6% (54/189 cases). The incidence of these lesions increased with age, and they were most prevalent in the sixth decade of life (12/30 cases, 40%). SMF were presented more often in the anterior wall than in the posterior wall. Most of the lesions were less than 1 mm in size. No case of SMF demonstrated expansive tumorous growth. Six of 54 cases of SMF displayed consecutive spread of SMF in almost all step sections of the cervix. The histological findings confirmed that SMF of the cervix is quite common existence among Japanese women. It is speculated that the mucosal region near the skin and/or cutaneous region near the mucosa may have stromal melanocytosis; malignant melanoma could develop from SMF of the cervix, which did not have junctional activity because of stromal melanocytic origin.