Objective: To study the clonality of palmar fibromatosis by molecular genetic analysis of X chromosome inactivation pattern at a polymorphic site of human androgen receptor gene (HUMARA).
Methods: Twelve female cases of palmar fibromatosis were enrolled into this study. Hematoxylin and eosin-stained sections of paraffin-embedded, formalin-fixed tissues were microdissected by laser capture microdissection technology in order to obtain the proliferative spindle cells. Tumor cells isolated from rectal adenocarcinoma in a female patient were used as positive control. The genomic DNAs were extracted with phenol and chloroform, digested with methylation-sensitive restriction endonuclease HpaII, and amplified by polymerase chain reaction (PCR) using primers targeted to a highly polymorphic short tandem repeat of HUMARA. The amplimers were separated on vertical 8% non-denaturing polyacrylamide gels and the patterns were visualized with ethidium bromide stain.
Results: The methodology for clonality analysis was validated in the positive control using rectal adenocarcinoma cells. Among the 12 cases studied, PCR amplification failed in 3 samples and 1 sample showed homozygosity which was not suitable for further analysis. Eight samples were successfully amplified and showed a random X chromosome inactivation pattern, suggesting polyclonality in these lesions.
Conclusions: Palmar fibromatosis is a polyclonal condition and should be considered as a form of non-neoplasmic fibroblastic proliferation.