ARTICLE
ejd.2011.1543
Auteur(s) : Emi Shikuma, Akihiro Fujisawa, Miki Tanioka,
Yoshiki Miyachi mtanioka@kuhp.kyoto-u.ac.jp
Department of Dermatology,
Department of Diagnostic Pathology,
Kyoto University,
54 Shogoin Kawaramachi Sakyo,
Kyoto 606-8507,
Japan
Colloid milium is a rare skin disease with deposition of
homogenous eosinophilic material in the dermis. The origin of the
deposit is thought to be collagen degeneration, which is proven by
UV light methods, although there are many uncertainties [1]. Here,
we present a case of colloid milium demonstrating amyloid
deposition of cytokeratin origin.
A 49-year-old woman presented with asymptomatic, skin-colored,
miliary papules, diameter 1-2mm, on the parietal region of her head
for 2 years (figure 1A).
The number of papules had gradually increased. She had no chronic
ultraviolet exposure or previous history of head injuries.
Histopathological examination revealed a deposition of
homogenous eosinophilic material in the papillary dermis (figure
1B). We diagnosed the papules as colloid milium. The
deposits were negative for PAS or Congo red stains, but were
positive for crystal violet (figure 1C)
and Dylon stain (figure 1D).
To investigate which amyloid origin constituted the deposition, we
tried stains including collagen-type 4, Elastica van Gieson (EVG),
cytokeratin 5 (CK5) (figure 1E)
and 34βE12 (an antibody specific for high molecular weight
cytokeratins 1, 5, 10) (figure 1F).
The former were negative, but the latter two stains were
positive.
Colloid milium is an uncertain clinical entity. The cause is
thought to be chronic exposure to UV light, contact with petroleum
products, application of bleaching creams containing hydroquinone,
and genetic predisposition [2]. The face, periorbital region, and
back of the hands are the most common sites of involvement. It
usually appears symmetrically. There are no clear diagnostic
criteria, but histological findings are useful. The diagnosis is
made together with the clinical and histological findings.
Generally, the deposits are PAS positive, crystal violet
negative, and Congo red negative in the special staining procedure,
and a few cases unlike the present patient have been reported
[2, 3]. Although the origins of the deposited materials are
unknown, they have been considered to originate from collagen
degeneration by UV light, and/or products of transformed
fibroblasts. In the present case, the depositions contained
cytokeratins, which are not found in the dermis. We believe the
origin of the cytokeratins was keratinocytes, because these
cytokeratins exist in basal cells of the epidermis.
The mechanism by which colloid milium is formed still remains
unclear, however, damage to the epidermal-dermal interface is one
of the possible causes because it usually develops in chronically
sun-exposed areas. In the present case, we speculated that the
deposition of cytokeratins might be a product of the previous
destruction of the basal cell layer, although the patient reported
no preceding trauma or UV exposure. Our case presents a clue to the
pathomechanism of colloid milium, which must be further
investigated in the future.
Disclosure
Financial support: none. Conflicts of interest: none.
References
1. Pourrabbani S, Marra DE, Iwasaki J, et al.
Colloid Millium : a review and update. J Drugs Dermatol 2007
; 6 : 293-296.
2. Parviz T, Safoura S, Somayeh H, et al.
Unilateral colloid milium: A rare presentation. Dermatology
Online Journal 2011 ; 17 : 6.
3. Kirtak N, Serhat IH, Karakok M, et al. A case
of adult colloid milium with chronic sun exposure. J
Dermatol 2002 ; 41 : 933-936.
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