The Value Of Counting Positive PHH3 Cells In The Diagnosis Of Uterine Smooth Muscle Tumors

Objective:The diagnosis of uterine smooth muscle tumors including leiomyosarcomas (LMS), smooth muscle tumors of uncertain malignant potential (STUMP),bizarre(atypical) leiomyoma(BLM),mitotically active leiomyoma(MAL) and leiomyoma(LM) depends on a combination of microscopic features,such as mitoses, cytologic atypia, and coagulative tumor cell necrosis.However, a small number of these tumors still pose difficult diagnostic challenges. The assessment of an accurate mitotic figures(MF) is one of the major parameters in the proper classification of uterine smooth muscle tumors. This assessment can be hampered by the presence of increased number of apoptotic bodies or pyknotic nuclei, which frequently mimic mitoses. Phospho-histone H3 (PHH3) is a recently described immunomarker specific for cells undergoing mitoses. We used mitosis specific marker PHH3 to count mitotic indexes(MI) of uterine smooth musle tumors and compared with the mitotic indexes of hematoxylin and eosin (H&E).Methods:The protein level of PHH3 and Ki-67 were detected by immunohistochemical SP method in 26 LMSs,16 STUMPs,30 BLMs,30MALs and 30LMs. Combined with mitotic index in H&E,computer pathological image analysis system was used in this studyResults:1. Overall PHH3 labeled cells undergoing the cell cycle, from prophase to telophase, revealing a strong brown staining of condensed chromosome. Anti-PHH3 labeled MFs were easily observed which permitted quick identification of the area of highest mitotic activity for subsequent counting.2. Anti-PHH3-labeled MI counts,H&E-stained MI counts and Ki-67 proliferation index in 132 cases of uterine smooth muscle tumors are 13.6±14.6,9.4±10.4,493.5±495.6 respectively.3. Anti-PHH3-labeled MI is higer than H&E-stained MI counts in each group.A strong correlation was found between them(r=0.964, p<0.05). Ratio of anti-PHH3-labeled MI to MI on H&E was basically constant from 1.4-2.2.4. There is also a positive correlation between H&E-stained MI counts and proliferation index ki67 (r=0.643, p<0.05). proliferation index ki67 and mitotic index on H&E have no obvious regular relationship of ration which is between 41-82.5. Leiomyosarcomas have significantly higher Anti-PHH3-labeled MI counts than STUMPs, BLMs, MALs and LMs (P<0.001). Although there were occasional exceptions, the mitotic index more than 20 was seen in approximately 85% of LMSs.The mitotic index based on PHH3 count form 11 to 20 is 81% in STUMPs and 63% in MALs.The counting value of PHH3 within the interval of 0 to 10 is 93% in BLMs. The number of mitotic figures no more than 5 is seen in nearly 100% of LMs. Mitotic index in STUMP and MAL groups is higher than that in BLM and LM groups(P<0.001).Conclusions:1. PHH3 compared with Ki-67 can response the real number of mitotic indexes in uterine smooth muscle tumors.2.Our results show that counting PHH3 is an useful index in the diagnosis of uterine smooth muscle tumors and it can provide a more accurate index instead of the time-honored mitotic figure counts at a certain ratio.3. If the counting value of PHH3 is more than 20,we consider this case has a higher chance to be malignant.