Several studies have shown that different
growth factors are involved in the pathogenesis of
palmar fibromatosis. The aim of the present study was to investigate whether
transforming growth factor alpha (
TGF-alpha) and its cellular
receptor, epidermal growth factor receptor (EGF-R), are expressed in
palmar fibromatosis. Nodules from 20 patients with
palmar fibromatosis and control normal palmar fascias were studied by the reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemistry. RT-PCR followed by Southern blotting demonstrated that
palmar fibromatosis nodules contained high levels of
TGF-alpha and
EGF-R
messenger RNA (
mRNA) transcripts, while normal fascias showed only low levels. Depending on the degree of cellularity and
fibrosis, the three following histological phases were recognized in
palmar fibromatosis nodules: proliferative, involutional, and residual. Immunohistochemistry, using alpha-smooth muscle actin as a cellular marker for myofibroblasts, revealed that
TGF-alpha and
EGF-R are co-expressed by myofibroblasts in the highly cellular areas of both proliferative and involutional phases, while they are absent or only focally detectable in the fibroblasts of normal fascia and in hypocellular and fibrotic areas of both involutional and residual phases. The restricted co-expression of
TGF-alpha and
EGF-R to myofibroblasts, the proliferating cellular component of nodules, suggests that an autocrine and/or juxtacrine growth stimulation by
TGF-alpha via the
EGF-R may be involved in the pathogenesis of
palmar fibromatosis.