ARTICLE
Keloid formation is a condition most commonly
seen in black patients characterized by abnormal wound healing and excessive
scar tissue formation [1]. The mechanism by which this occurs is unclear
but abnormal fibroblast metabolism and enhanced response to growth factors
have been implicated in keloid formation. One study measured cytokine
levels produced by peripheral blood mononuclear cells in black patients
with keloids and found that there are decreased antifibrotic agents including
IFN-alpha, IFN-gamma, and TNF-beta and increased profibrotic agents including
IL-6 [2]. Interestingly, IFN-alpha has been reported to be antifibrotic
in vitro and of value clinically in the treatment of keloids [3].
Hypertension is a disease that is also more common and severe in black
patients [4]. Although there are many theories, the cause of essential
hypertension is unknown. More recent studies have examined immunologic
factors in the pathogenesis of hypertension specifically looking at the
architecture of the resistance arterioles. Endothelial dysfunction with
subendothelial accumulation of monocytes occurs in hypertension [5]. In
addition, upregulation of the profibrotic cytokine TGF-beta in monocytes
of hypertensive patients has been described [6]. There appears to be inappropriate
growth of vascular smooth muscle cells possibly secondary to immune system
alterations or abnormal growth factor response in patients with essential
hypertension [7].
The increased incidence and severity of both keloids and hypertension
in black patients prompted this investigation to determine whether there
is an association between keloids and hypertension. More specifically,
it examines the incidence of hypertension in patients with a history of
keloids as compared to that of a control group with tinea versicolor,
a dermatologic disease which has not been associated with keloids or hypertension.
Materials and methods
After obtaining IRB approval, we used the Jackson Memorial Hospital
(JMH) computerized medical records as a database. JMH is a public hospital
that provides comprehensive health care for its patients. It utilizes
a computerized medical records system to record patient diagnoses. A list
of patients between the ages of 18 and 75 years old with a diagnosis of
keloids in their medical record from 1986 to 1998 was generated from this
computerized database. Patients with a diagnosis of tinea versicolor were
chosen as the control group and a similar list was generated. We chose
tinea versicolor as the control group because it is a common dermatologic
diagnosis with a similar age and gender distribution to that of keloids.
Additionally, it has not been associated with hypertension in any previous
studies. A description of the patient age and gender distribution is summarized
in Table I.
We reviewed the charts in each group to determine which patients also
had a diagnosis of essential hypertension using the current accepted definition
of hypertension [4]. At JMH, blood pressure values are obtained at routine
clinic visits for all patients and documented in the medical record. Patients
are at rest and the blood pressure is taken in a seated position. In all
cases, patients were defined as hypertensive if it was documented in their
medical record or if they had a diastolic blood pressure greater than
90 mmHg on two or more occasions. We excluded patients with isolated systolic
hypertension and patients with hypertension secondary to other causes.
Results
As expected, the study was limited to black patients because the number
of white patients was small and insufficient for comparison. Of the 429
charts reviewed, we found no statistically significant difference in the
overall incidence of hypertension between the keloid patients (20.3%)
and the control tinea versicolor patients (18.2%). However, we did find
an increased hypertension incidence in black patients with keloids under
thirty years old as compared to the control group. Nine of 129 (7%) black
patients with keloids under thirty had hypertension as compared to none
of the 65 (0%) black patients with tinea versicolor under thirty. Although
the data points to an increased risk of hypertension in younger patients
with keloids, none of the controls had hypertension so an accurate estimate
of relative risk cannot be calculated.
Discussion
Based on the results of the study, there does appear to be an association
between keloids and hypertension in black patients. This study suggests
that although the overall incidence of hypertension is the same in patients
with keloids as compared to controls, the age of onset may be earlier
in the keloid group.
A few studies have previously attempted to assess an association between
keloids and hypertension [8, 9]. One study reported an increased incidence
of hypertension in both black and white patients with a history of keloids
as compared to a control group [8]. Our study did not reproduce these
results. Possibly they studied a younger patient population, however,
unfortunately ages were not specified.
The association between keloids and hypertension may suggest a common
link in the etiology of both conditions. Recent investigations suggest
that this link may be related to immunologic factors. It has been shown
that cytokine alterations in vitro contribute to enhanced fibroblast
growth and keloid formation [10]. Recent studies of hypertension are also
beginning to examine the effect of the immune system on vascular smooth
muscle cells and cardiac myocytes which appear to have a propensity for
hypertrophy and hyperplasia, specifically in the black population [11].
In addition, the histology of hypertensive nephrosclerosis in black patients
is distinctly different than that of white patients with a pathologic
picture of myointimal fibroplasia and mucopolysaccharide deposition [9].
These findings may point to a possible hyperproliferative state in black
patients which may predispose them to hypertension and keloid formation.
The pathophysiology behind essential hypertension and keloids in black
patients may be related in that they both could have altered levels of
circulating cytokines that contribute to excess fibrous tissue formation.
In addition to cytokines, there are other factors such as alphaglobulins,
protease inhibitors, and collagenase which have been implicated in keloid
pathogenesis [12]. The role of these factors in hypertension requires
further study. Elucidation of these factors, in addition to immune system
alterations, may be the key to improved understanding and improved treatment
of these two disease processes.
Article accepted on 29/8/02
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