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Dermatology > PHOTO-RELATED DISEASES
Colloid Milium
Article Last Updated: Feb 21, 2007
AUTHOR AND EDITOR INFORMATION
Section 1 of 11  
Author: Susan Cooper, MRCGP, MRCP, MD, Consultant Dermatologist, Department of Dermatology, Churchill Hospital, Oxford, United Kingdom
Susan Cooper is a member of the following medical societies: Royal College of Physicians
Coauthor(s):
Elizabeth Soilleux, PhD, MRCPath, Consultant Pathologist and Honorary Senior Clinical Lecturer, Department of Cellular Pathology, John Radcliffe Hospital, UK
Editors: Marjan Garmyn, MD, PhD, Professor, Faculty of Medicine, Katholieke Universiteit Leuven, Belgium; Chair and Adjunct Head, Department of Dermatology, University of Leuven, Belgium; David F Butler, MD, Professor of Dermatology, Texas A&M University College of Medicine; Director, Division of Dermatology, Scott and White Clinic; Director Dermatology Residency Training Program, Scott and White Clinic; Edward F Chan, MD, Clinical Assistant Professor, Department of Dermatology, University of Pennsylvania School of Medicine; Catherine Quirk, MD, Clinical Assistant Professor, Department of Dermatology, Brown University; Dirk M Elston, MD, Director, Department of Dermatology, Geisinger Medical Center
Author and Editor Disclosure
Synonyms and related keywords:
colloid pseudomilium, colloid degeneration of the skin, nodular colloid degeneration, elastosis colloidalis conglomerata, colloid infiltration, military colloidoma, hyaloma
Background
Colloid milium is a rare condition characterized by (1) the presence of multiple, dome-shaped, amber- or flesh-colored papules developing on light-exposed skin and (2) the observance of dermal colloid under light microscopy. The 4 variants are (1) an adult-onset type, (2) a nodular form (nodular colloid degeneration), (3) a juvenile form, and (4) a pigmented form, thought to be due to excess hydroquinone use for skin bleaching.
Pathophysiology
Colloid milium is a degenerative condition linked to excessive sun exposure and possibly exposure to petroleum products and hydroquinone. The origin of the colloid deposition in the dermis is not certain, but it is thought to be due to degeneration of elastic fibers in the adult form and due to degeneration of UV-transformed keratinocytes in the juvenile form. Juvenile colloid milium is inherited.
Frequency
International
The condition is rare, but more than 100 case reports are present in the world literature. No known figures exist on prevalence.
Mortality/Morbidity
Most cases persist with no natural resolution. Lesions reach their peak within 3 years, after which very few new papules occur.
Race
Colloid milium is more common in fair-skinned individuals.
Sex
The adult form is more common in males.
Age
The rare juvenile form occurs before puberty. Adult colloid milium is more common in elderly patients.
History
Papules develop gradually over the facial area and light-exposed sites. Patients are usually asymptomatic, but they may have transient itching in affected areas.
Physical
The physical findings are usually limited to the skin.
- Skin lesions: Amber, waxy, partially translucent, firm papules occur in crops, ranging from 1-5 mm in diameter. Gelatinous material can be expressed. In the nodular form, larger nodules (5-10 mm) or plaques develop. The underlying skin may be thickened, furrowed, and hyperpigmented. In the pigmented form, the papules are gray-black and confluent or clustered.
- Skin distribution: The lesions occur on light-exposed skin, with the cheeks, periorbital area, nose, ears, and neck most frequently involved; however, lesions may also occur on the backs of the hands and forearms. Nodules arising on one side of the face and the ipsilateral forearm have been described in a taxi cab driver. Upper eyelid margin involvement alone has been reported. Juvenile colloid milium may be associated with ligneous conjunctivitis or ligneous periodontitis.
Causes
- The classic adult and nodular forms are believed to be due to excessive sun exposure, which appears to cause degeneration of elastin. Evidence to support this comes from the exposed site distribution and the tendency for the condition to occur in individuals with fair complexions and outdoor occupations.
- The juvenile form is inherited, perhaps suggesting an inherited susceptibility to UV light. Autosomal recessive inheritance has been reported.
- An outbreak of colloid milium occurred in oil refinery workers in the tropics. This may represent an interplay between light and petroleum constituents. Phenols have been suggested as causative agents.
- Prolonged use of hydroquinones has resulted in the development of the pigmented form of colloid milium, sometimes in association with ochronosis.
Amyloidosis, Lichen
Basal Cell Carcinoma
Epidermal Inclusion Cyst
Erythropoietic Protoporphyria
Lipoid Proteinosis
Molluscum Contagiosum
Sarcoidosis
Sebaceous Hyperplasia
Steatocystoma Multiplex
Syringoma
Trichoepithelioma
Tuberous Sclerosis
Procedures
- Skin biopsy
- Light microscopy is necessary.
- Electron microscopy may be necessary to distinguish between colloid and amyloid because these 2 entities look similar under light microscopy.
Histologic Findings
Typically, fissured eosinophilic colloid masses are seen in the dermis.
In the classic adult form, the colloid is located in the upper and mid dermis and in defined islands, with a very superficial, subepidermal layer of the papillary dermis usually being spared (Grenz zone). The colloid has a homogeneous eosinophilic appearance with some fissuring. Fibroblasts may be aligned along the edges of these fissures. Solar elastosis is marked and closely approximated to the colloid. Hair follicles and sebaceous glands are well preserved.
In the nodular form, the vast majority of the dermis is filled with glassy eosinophilic colloid.
In the pigmented form, deposits are similar to those of the classic adult form, except that they show a light-golden pigmentation similar to ochronosis.
In the juvenile form, the Grenz zone is usually absent, with the islands of amorphous colloid lying close to the basal layer of the epidermis. These islands show some clefting with intervening spindle or stellate fibroblasts. Solar elastosis is absent. In the nodular form, the vast majority of the dermis is filled with colloid.
Because colloid cannot be distinguished from amyloid under light microscopy alone and because colloid, like amyloid, stains positively for periodic acid-Schiff stain, it can be difficult to distinguish it from amyloid. However, colloid is usually negative for the amyloid stain methyl (crystal) violet. Colloid may also sometimes yield weakly positive results and may show green birefringence with Congo red stain. Amyloid in the skin frequently immunostains positively for cytokeratin or immunoglobulin light chain, which colloid should not. However, if these special stains and immunostains prove inconclusive, electron microscopy may be necessary.
Medical Care
- No treatment is available that is entirely satisfactory.
Surgical Care
- Dermabrasion, cryotherapy, and diathermy have been tried with limited success. Advice about sunscreen use may also be helpful. Systemic ascorbic acid and exfoliating agents have also been tried with variable results. The Er:YAG laser may be more successful than dermabrasion.
Prognosis
- Lesions remain static and do not resolve.
Patient Education
- Genetic counseling is advisable for the rare juvenile form.
- Sun avoidance seems sensible, but no evidence suggests that this intervention is beneficial.
Medical/Legal Pitfalls
- The major pitfall is misdiagnosis, especially with the rare childhood form, which might be confused with tuberous sclerosis. However, if a biopsy sample is taken from the lesion and analyzed, this pitfall should be avoided.
The authors and editors of eMedicine gratefully acknowledge the contributions of previous coauthor, Ravi Ratnavel, MD, to the development and writing of this article.
| Media file 1:
Hematoxylin and eosin–stained section of skin (X40) showing a central focus of amorphous, eosinophilic, homogenous colloid with surrounding fissuring. |
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Media type: Photo
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| Media file 2:
Elastic van Gieson stain of the same area showing strong (black) staining of the colloid for elastin. |
 | View Full Size Image | |
Media type: Photo
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Colloid Milium excerpt Article Last Updated: Feb 21, 2007
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