Introduction
Colloid milium is a rare cutaneous deposition disorder characterized by the presence of asymptomatic multiple dome-shaped semi-translucent waxy yellowish or skin-colored papules ranging in size from 1 to 4 mm.[1,2] The underlying skin may be thickened and may show furrows. It manifests over the face and dorsum of forearms and arms due to chronic sun exposure. It has been classified into four different types namely, 1) juvenile type originating from degenerating keratinocytes, 2) adult type from degenerating elastic fibers, 3) pigmented type due to toxic effects of petroleum products and hydroquinone, and 4) nodular colloid occurring in old age. Here we report a rare case of adult colloid milium with purpura as an unusual presentation.
Case Report
A 35-year-old fair complexioned male was examined in a skin outpatient department for asymptomatic non-progressive symmetrical skin lesions over the forearm and hands for an eight-year duration. A history of trauma-induced purpura was present over lesion sites. There were no systemic complaints and no family history of similar illnesses. The patient is a financier by occupation with a moderate degree of exposure to sunlight. Topical application with sunscreens and emollients showing no improvement.
Dermatological examination revealed bilateral symmetrical numerous skin-colored to yellowish waxy papules involving the dorsa of the lower half of the forearms and hands [Figure 1]. Purpura was observed over the waxy papules and could be induced selectively over the lesion areas by stroking [Figure 1]. Face, mucosa, and tongue were normal. Systemic examinations were normal. Basic investigations, complete hemograms, coagulation profiles, serum proteins, and immunoglobulin assays were normal. X-ray of the chest and ultrasound abdomen was also normal.
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Figure 1: Clinical picture showing yellowish translucent waxy papules with purpura on the dorsum of the forearm
Biopsy from the waxy purpuric papules under hematoxylin and eosin showed a homogenous globular eosinophilic mass with cleft-like spaces in the papillary dermis. A grenz zone separated the thinned-out epidermis from the homogenous mass [Figure 2]. Fibroblasts, numerous red blood corpuscles, and damaged blood vessels were also appreciable within and adjacent to the mass [Figure 2]. The deeper dermis and subcutis were normal. Special staining with Congo red was negative and Verhoff-von Gieson (VVG) staining revealed strong black degenerated elastic fibers (solar elastosis) beneath the mass and upper dermis [Figure 3]. Immunohistochemical study with cytokeratin markers was negative for the homogenous mass thereby excluding conditions with keratinocyte origin namely primary cutaneous amyloidosis and juvenile colloid milium [Figure 4]. A diagnosis of adult-type colloid milium was made based on the above clinicopathological findings.
Figure 2: H and E section of the waxy purpuric papule showing homogenous eosinophilic mass with cleft-like spaces, fibroblasts, and red blood corpuscles. (10 × 20)
Figure 3: Verhoeff-van Gieson stain showing strong staining of degenerated elastic fibers (black) and a prominent grenz zone. (10 × 20)
Figure 4: immunostain with cytokeratin markers: homogenous-fissured mass remains unstained while the epidermis shows positive staining. (10 × 20)
Discussion
Although many conditions are to be considered differential diagnoses, only amyloidosis, especially nodular and primary systemic amyloidosis, mimics adult colloid milium more closely.[3] They share indistinguishable common features namely waxy translucent papules, clinically and homogenous eosinophilic fissured mass, histologically.
Purpura following a trivial injury like stroking or pinching is considered one of the cardinal signs in primary systemic amyloidosis and the manifestation of purpura in the lesion sites in this patient made clinical differentiation from primary systemic amyloidosis more difficult. Special stains were done to differentiate the two conditions. A negative result with Congo red excluded amyloidosis of both cutaneous and systemic origin. A strong staining of degenerating elastic fibers in the upper dermis beneath the mass and upper dermis with VVG stain confirmed a diagnosis of adult colloid milium. According to Lewis et al.,[4] colloid has no fool proof distinctive staining characteristic of its own, thus, diagnosing colloid is mainly accomplished by negative results with amyloid stains. Further, colloid has been reported to show positive staining with crystal violet and Congo red and give fluorescence with thioflavin T on frozen rather than in paraffin sections.[1]
Purpura as a component of colloid milium has very few references in literature and the interesting report by Sevigny et al.,[5] stroke-induced purpura was documented in three cases among which two had juvenile colloid milium and one had adult colloid milium. Purpura was attributed to the ultramicroscopic infiltration of colloid material in the dermal blood vessels with a resultant decrease in the elasticity of the blood vessels. It was compared to a similar deposition of amyloid in the vessel wall in primary systemic amyloidosis. The presence of red blood corpuscles in the damaged vessel in the vicinity of the eosinophilic mass was histologically supporting clinical purpura but colloid deposits in the vessel wall were not detected which probably requires ultramicroscopic studies.
The demonstration of amyloid P, an essential component of elastic fibers under immunohistochemistry, and distinguishing delicate short wavy branching filaments of diameters 1.5–2.0 nm compared to 6–10 nm of amyloid under electron microscopy are other higher studies that differentiate adult colloid milium from primary systemic amyloidosis.[6] Colloid milium does not contain laminin or type IV collagen unlike amyloidosis or lipoid proteinosis.[1]
Successful treatment has been reported with dermabrasion and more recently with ablative and fractional laser resurfacing of affected skin.[7] The treatment of this patient with topical sunscreens and microdermabrasion showed no promising results and fractional laser surfacing in the future might prove helpful.
Conclusion
This case of adult colloid milium is documented for its rarity and its similarities to skin lesions of primary systemic amyloidosis both clinically and histologically. Purpura, a less-described feature in adult colloid milium, is also highlighted. The importance of special staining and immunostaining with cytokeratin markers is emphasized in distinguishing adult colloid milium from other types of colloid milium as well as from amyloidosis.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
References
1. Weeden D, Strutton G. Cutaneous deposits Weeden D, Strutton G. Skin Pathology 2nd ed London Churchill Livingstone 2002:434–36.
2. Rahman SB, Ul Bari A, Mumtaz N.
Colloid milium:A rare cutaneous deposition disease. J Pak Med Assoc 2008;58:207–9.
3. Desai AM, Pielop JA, Smith-Zagone MJ, Hsu S.
Colloid milium:Ahistopathologic mimicker of nodular amyloidosis. Arch Dermatol 2006;142:784–5.
4. Lewis AT, Le EH, Quan LT, Krishnan B, Schulmeier J, Hsu S. Unilateral
colloid milium of the arm. JAm Acad Dermatol 2002;46:S5–7.
5. Sevigny GM, Ford MJ. Stroke-induced purpura in lesions of
colloid milium. Cutis 1995;56:109–13.
6. Pourrabbani S, Marra DE, Iwaski J, Fincher EF, Ronald LM.
Colloid milium:A review and update. J Drugs Dermatol 2007;6:293–96.
7. Ammirati CT, Giancola JM, Hruza GJ. Adult-onset facial
colloid milium successfully treated with the long-pulsed Er:YAG laser. Dermatol Surg 2002;28:215–19.
