Collagen balls in cervical-vaginal smears

Objective: To describe the recent detection of collagen balls in cervical-vaginal specimens from 7 women within the previous 2 years. Study Design: Papanicolaou-stained cervical-vaginal specimens, 3 conventional and 4 ThinPreps™ (Cytyc Corp., Boxborough, Massachusetts, U.S.A.), were reviewed due to the presence of structures indistinguishable from collagen balls. Results: The structures displayed 3-dimensionality, a hyalinized core and a covering of benign-appearing cells, features identical to those seen in collagen balls from serous cavity fluids. Averaging 94 x 60 μm, they were similar in size to a human oocyte at ovulation. Their presence did not correlate with any concurrent Pap smear findings or previous medical history. Conclusion: Since collagen balls have previously been reported to occur only in serous cavity fluids, they are thought to arise at those locations. We propose that collagen balls are transported via the fallopian tube and uterine fundus to the cervix, much in the same way that an ovum is transported to the uterine fundus for implantation. The likelihood of such an event is most probably quite low. The recent finding of 7 cases of collagen balls may correlate with an increased prevalence of collagen balls in peritoneal fluids, thus increasing the probability of their transport to the cervix.