A
proliferating
pilar
tumor
(
PPT
)
is
a
rare
neoplasm
arising
from
____________________
isthmus
region
of
the
outer
root
sheath
of
the
hair
follicle
.
It
is
also
commonly
____________________
a
proliferating
trichilemmal
cyst
or
,
less
commonly
,
proliferating
follicular
-
cystic
neoplasm
.
It
____________________
first
described
by
Wilson
-
Jones
as
a
proliferating
epidermoid
cyst
in
1966
.
PPT
was
then
distinguished
from
proliferating
epidermoid
cysts
____________________
1995
.
It
occurs
most
commonly
on
the
scalp
in
women
older
____________________
50
years
.
Most
tumors
arise
within
a
preexisting
pilar
____________________
.
Even
____________________
they
usually
are
benign
in
nature
,
malignant
transformation
with
local
____________________
and
metastasis
____________________
been
described
.
A
tentative
stratification
of
PPTs
____________________
groups
as
benign
,
low
-
grade
malignancy
,
and
high
-
grade
malignancy
has
been
introduced
.
They
may
be
____________________
in
an
autosomal
-
dominant
mode
,
linked
to
chromosom
e
