ARTICLE
Primary localized cutaneous amyloidoses (PLCA) are
dermatoses characterized by the deposition of extracellular amyloid, a particular
fibrillary substance; they include the following types: the rare nodular
form with systemic evolution, the less rare macular form and, finally, the
most common papular form or lichen amyloidosus [1].
Lichen amyloidosus is characterized by an eruption of itchy, hyperkeratotic,
and reddish-brown papules over the shins, with a subsequent involvement
of feet, thighs, calves, and ankles. On the contrary, macular amyloidosis
(MA) is characterized by symmetrical, brownish and not clearly delimited
macules, with the typical reticulated, rippled appearance, is moderately
itchy, distributed over the upper back and arms, and occasionally on the
chest and buttocks.
To our knowledge, macular and papular amyloidosis do not evolve into
a systemic form and are considered to be opposite expressions of the same
pathologic process, as they can both exist in the same patient (biphasic
amyloidosis) [2]. MA was first described by Palitz and Peck in 1952 [3],
in its etiopathogenesis, genetic, racial (phototype) and environmental
factors are suspected to be important. However, scratching appears to
be the first and most important factor in the development of the lesions
[2]. This form is most frequently observed in the populations of Central
and Southern America, the Middle East and Asia [4].
In Japan, Hidano et al. [5] observed an unusual brownish pigmentation
over bony regions such as clavicle, scapula, vertebrae and limbs of 23
patients. Usually, pigmented skin showed a rippled and reticulated surface
and occurred after the use, for many years, of a nylon towel or scrub
brush to clean the skin. In the same patients, histologic examination
showed postinflammatory melanin deposits in the upper dermis and altered
melanophages in the papillary dermis. Amyloid deposit in the papillary
layer was observed only in one case. These authors proposed the term of
friction melanosis for this pigmented dermatosis.
Subsequently, the same group [6] reported 6 additional patients and
in all of them histologic analysis revealed the presence of amyloid deposits
in the papillary dermis.
Based on the above observation and on their own results, in 1988, Wong
and Shilin [7] referred to this condition with the term friction amyloidosis.
The same authors correlated it with MA, which is frequently observed in
Japanese persons, because of its etiopathogenetic, clinical histological
and ultrastructural findings. It seems that friction amyloidosis is relatively
unknown in the West.
In a survey on skin pathology findings in a cohort of 1,500 adults and
elderly subjects, we have described friction amyloidosis, diagnosed by
electron microscopic evaluation, in four women aged, respectively, 60,
76, 76 and 70 years with phototype IV [8, 9]. To our knowledge, this dermatosis
has never been reported before in Italy. Recently, we have also described
another case of friction amyloidosis in a 46 year-old Italian woman with
phototype IV [10].
In this paper, we report 24 new Italian patients who were not known
to be affected by this pigmented dermatosis.
Case reports
Since January 1998, 24 Italian patients, 4 men and 20 women, all with
phototype IV, came to our observation for hyperpigmentation of the skin
over the upper part of the back, of the scapulae, interscapular space,
arms, legs and buttocks (table
I). Twenty-one of these patients came from our Department of Neurology
and Geriatrics while 3 were out-patients.
Skin examination revealed dark brownish rippled macules, with a reticulated
pattern and poorly delimited. The skin over the bony regions was more
pigmented than other areas (Figs.
1 and 2). No papulo-nodular
lesions were observed. The macules were moderately itchy and had been
present over the skin for the last 10-20 years. All patients had been
using cotton towels, horse-hair gloves or artificial and rough sponges
for many years, every time they took a shower or bath, to scrub the areas
where the lesions were present at clinical examination. Only one male
patient out of 24 showed atopy; no other skin lesions were observed.
All patients were in good general condition and in all of them routine
blood examinations and urine analysis were within the normal limits. Bence-Jones
protein in urine was absent, thyroid function, calcitonin and adrenocorticotropin
plasma levels were normal; neurological examination showed no sensory
abnormalities over the lesions; X-rays of the affected bony regions were
normal and patch tests (European Standard Series) were negative. No patient
had taken drugs which could have caused the cutaneous pigmentation and
there were no family members suffering from a similar skin disorder.
After informed consent, skin biopsies, with a punch biopsy 5 mm in diameter,
were taken from involved skin in 15 patients. Histological examination
showed a normal, well-pigmented epidermis with a regularly represented
corneous layer; in 6 patients, deposits of PAS-positive material were
found in the papillary dermis with numerous vessel structures (Fig.
3). At electron microscopy, no regressive changes were observed
in the keratinocytes. The cells contained an increased number of well
structured melanosomes. The melanocytes showed an increase in subcellular
organelles consistent with functional activation. Globular deposits of
fibrillary material were seen at the dermo-epidermal junction in the 15
patients; sometimes the basal lamina of keratinocytes and melanocytes
was partially fragmented in the proximity of amyloid deposits (Fig.
4).
The patients' histories, the clinical examinations and the electron
microscopic evaluations allowed us to diagnose macular or friction amyloidosis
in the 15 biopsied patients. The remaining nine who refused consent for
a biopsy had a generic diagnosis of friction dermatosis.
Comments
As mentioned above, different authors have already reported a clinical
condition characterized by hyperpigmentation of the skin over the bony
regions of the back and limbs occurring after prolonged rubbing with nylon
towels and brushes [5-7, 11]. Also, the terms introduced reflected their
attempts to interpret the mechanisms at the basis of this dermatosis:
a) towel melanosis, b) friction melanosis, c) nylon clothes friction dermatosis,
d) nylon brush macular amyloidosis, etc. [5-7, 11].
Histologic examination showed pigmentary incontinence and, sporadically,
deposits of amyloid in the papillary dermis. Various stains can be used
to evidence amyloid, Congo red provided the most specific results giving
an apple-green birefringence, probably due its beta-pleated sheet configuration;
however, crystal violet and PAS were the most sensitive [2].
In 1998, Wong and Shilin [7] systematically applied electron microscopy
and were able to observe amyloid in all of their patients; subsequently
electron microscopy proved to be an essential method of analysis for the
diagnosis of cutaneous amyloidoses [12, 13].
Pathogenetically, prolonged frictional trauma would induce activation
of melanocytes with an increase of melanin in the keratinocytes and melanophages
in the papillary dermis [7]. Sometimes, an edematous condition surrounding
the melanocytes, as a result of the friction, could inhibit the passage
of melanosomes to keratinocytes. Consequently, melanosomes could package
into autophagic vacuoles within the melanocytes. All these mechanisms
might explain the cutaneous pigmentation [7, 14].
Regarding amyloid histogenesis, the fibrillary body theory states that
focal epidermal damage and filamentous degeneration of keratinocytes is
followed by apoptosis and transformation, by dermal fibroblasts and histiocytes,
of filamentous masses (colloid bodies) into amyloid depositing in the
upper papillary dermis. However, no clear explanation exists of how the
alpha type of keratin tertiary structure is degraded and converted into
beta-pleated sheet configuration of amyloid [15].
On the contrary, according to the secretion theory, the same damaged
basal cells would produce the amyloid which would accumulate at the dermal-epidermal
junction. In fact, electron microscopy has revealed the distruption of
the lamina densa above the amyloid deposits with opening allowing the
amyloid to drip into the papillary dermis [4]. It is also observed that
dermal nerve fascicles present mild morphological changes of unmyelinated
nerve fibers. Superficial nerve bundles also show a normal appearance;
the reduplication of Schwann cell basal lamina could be considered as
indirect evidence of nerve lesion followed by repair [13].
To date, no convincing explanation exists for the immunologic tolerance
to amyloid. It has been suggested that its beta-pleated sheet configuration
might protect it from degradation and phagocytosis [4]. However, the reason
why amyloid storage does not trigger other mechanisms of active or passive
transepidermal elimination is not known [16]. Bony region, adequate friction
trauma and a peculiar rubbing device are important factors for the onset
of the macular and friction amyloidosis [10]. The skin over the bony regions
is between an active scratching or friction force and a rigid surface.
The repeated mechanical trauma, over a long period of time, might cause
the rippled aspect of the skin, while the reticulate pattern might be
due to different directions of scratching and rubbing.
An allergic genesis for friction amyloidosis
was suspected by Japanese authors [7, 11], but repeatedly performed patch
tests for nylon or its chemical components were negative in their patients;
thus, they attributed importance to the physical properties of these components,
mostly to the hardness of fibers. In this respect, it is possible to find
on the market, different types of rubbing gloves made of horse hair, vegetal
fibers, artificial fibers or mixed ones. The mixed-fibers type is constituted
of components of animal, vegetal and artificial origin, with different
shapes and diameter, treated in order to obtain the desired length and
resistance. On the contrary, artificial sponges are formed by plastic
materials, made industrially.
Moreover, in our 15 biopsied patients, history, location, and features
of the lesions, together with their histological and ultrastructural findings,
allowed us to exclude the macular posterior pigmentary incontinence (MPPI)
and notalgia paraesthetica [17, 18]. MPPI is a condition strongly resembling
macular amyloidosis but without tendency towards amyloid formation in
the skin [17]. Notalgia paraesthetica is a primary sensory neurophatic
of unknown etiology affecting the posterior rami of the second to sixth
thoracic spinal nerves. It usually causes itch, paraesthesiae and tenderness
over the upper back. Over the area of the itch, skin is similar to that
of MA, with deposits of amyloid in the papillary dermis; however, MA is
not only seen in this area of the back, but also occurs in other parts
of the body [18]. In the nine patients without biopsy, the history and
the location of the lesions allowed us to suspect macular or friction
amyloidosis. Moreover, it has also been proposed that MA, MPPI and notalgia
paraesthetica might be three related and frequently overlapping conditions
[17].
All populations in which PLCA are particularly prevalent [2] tend to
show a high phototype; it is also known that this kind of skin tends to
react to friction with pigmentation. Moreover, sunny weather might contribute
to a further increase in pigmentation and it appears likely that the fact
that the first reports of friction amyloidosis came from Japan, where
PLCA are also frequent and, in particular, MA [4], can be non fortuitous.
Thus, it might be possible to suggest, in the genesis of PLCA and friction
amyloidosis, a phototype susceptibility with an important role for environmental
factors such as hot-humid weather and traditional or individual habits
(use of brushes, nylon and cotton towels, horse-hair gloves, artificial
and rough sponges).
We think that our report is important for the following reasons: a)
macular or friction amyloidosis is relatively unknown in Western countries;
b) it is necessary to study the lesions by electron microscopy in order
to identify amyloid; c) it seems appropriate to discourage the use of
vigorous hygiene practice which might induce the occurrence of MA mostly
in patients with phototype IV and V.
Article accepted on 22/5/01
CONCLUSION
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