[Distinction between benign and malignant pheochromocytomas].
OBJECTIVE
To investigate the differences in morphology, immunohistochemistry, DNA ploidy status, LOH and MSI of 11q13 and 1p between benign and malignant pheochromocytomas, and to find the marker or markers useful in distinction between benign and malignant pheochromocytoma or for predicting the malignant potential of this tumor.


METHODS
Twenty-two cases of clinically documented benign and malignant pheochromocytomas from the files of Peking Union Medical College Hospital were analyzed. Aside from histological study, Ki-67, p53, CgA, S-100, PCNA and survivin immunohistochemistry studies were performed. DNA ploidy status was assessed by flow cytometry on cell suspensions prepared from formalin-fixed, paraffin-embedded sections. Twelve tumors (7 benign and 5 malignant) with paired normal tissues were microdissected. Tumor and normal tissue DNA were extracted. The obtained DNAs and 8 microsatellite markers related to 11q13 and 1q were subjected to PCR amplification for analysis of LOH and MSI.


RESULTS
None of the tumors showed atypical mitosis, only 1 malignant tumor had a mitotic count > 1/10 HPF (2.3/10 HPF). Two malignant tumors exhibited confluent necrosis. Ki-67 index was low in benign tumors (average 0.73%), and high in malignant tumors (average 2.4%). The difference of Ki-67 index between benign and malignant tumors was statistically significant. DNA ploidy status did not correlate with malignancy. Although LOH and/or MSI of 11q13 and 1p were observed in several tumors, a statistically significant difference could not be reached due to the small number of tumors analyzed.


CONCLUSIONS
Only Ki-67 index (> 3%) is an useful marker for distinguishing benign from malignant or for predicting the malignant potential of pheochromocytoma.
Liu
Tong-Hua
TH
Department of Pathology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100730, China.
Chen
Yuan-Jia
YJ
Wu
Sha-Fei
SF
Gao
Jie
J
Jiang
Wei-Jun
WJ
Lu
Zhao-Hui
ZH
Guan
Jian
J
Wei
Shuan-Zeng
SZ
Luo
Yu-Feng
YF
Cao
Jin-Ling
JL
Wan
Jian-Wei
JW
D000310:Adrenal Gland Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D000328:Adult; D000368:Aged; D014408:Biomarkers, Tumor / Q000378:metabolism; D004273:DNA, Neoplasm / Q000235:genetics / Q000378:metabolism; D005260:Female; D006801:Humans; D019394:Ki-67 Antigen / Q000235:genetics / Q000378:metabolism; D019656:Loss of Heterozygosity; D008297:Male; D008875:Middle Aged; D009362:Neoplasm Metastasis; D010673:Pheochromocytoma / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D016133:Polymerase Chain Reaction; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism; D001749:Urinary Bladder Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology
D014408:Biomarkers, Tumor; D004273:DNA, Neoplasm; D019394:Ki-67 Antigen; D016159:Tumor Suppressor Protein p53