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Pathology of Colloid Milium

Dr Sampurna Roy MD            

Dermatopathology Case 5

Diagnosis: Colloid Milium




Colloid milium is an unusual cutaneous disorder characterized by multiple cystic papules.

It is a degenerative process in which the papules are located in the photoexposed areas.

The material in the dermis represent a degeneration product of elastic fibers which is induced by solar radiation.

Colloid milium and colloid degeneration include at least four distinct clinicopathological conditions:

- Classic adult type colloid milium  

- Juvenile colloid milium

- Pigmented colloid milium (hydroquinone related)

- Colloid degeneration (paracolloid)

Classic adult type colloid milium :

- The adult form develops in sun-exposed parts of the body in patients who have actinic-damaged skin.

- Develops in mid-adult life.

- Plenty of yellow-brown, semitranslucent papules or plaques (1 to 4 mm in diameter) are seen in the cheeks, ears, neck, and dorsum of the hands.

- Predisposing factors are exposure to petroleum products and/or excessive sun sunlight.

Juvenile type colloid milium :

- Exceedingly rare and develop prior to puberty.

- Papules or plaques are seen on the face and neck.

- Some cases are probably examples of erythropoietic protoporphyria.

Pigmented type colloid milium :

- Gray to black papules on the face, following the excessive use of hydroquinone bleaching cream.

Colloid degeneration :

- Nodules or plaque-like areas, on the face and is probably a heterogeneous group.

Histopathology :

   this material into smaller islands.  

Adult form:  Histopathology images above:

- Nodular masses of homogeneous, eosinophilic material expanding the papillary dermis and extending into the mid dermis.

- Fissure and cleft divide this material into smaller islands and fibroblasts are commonly aligned along the line of fissuring.

- A thin grenz zone of normal collagen, often with elastic fibers (which are also present between and below the colloid masses), separates the colloid material from the thinned overlying epidermis.

- Colloid material may be stained positively with crystal violet and Congo red and fluorescence with thioflavin T (better result on frozen sections).

- Absence of laminin or type IV collagen differentiates colloid milium from lipoid proteinosis and primary cutaneous amyloidosis.

Juvenile form:

- In most areas grenz zone is absent and basal layer may show hyalinization with a transition towards the dermal material.

- The colloid is PAS positive and sometimes, methyl violet positive but it is usually Congo red negative.

Pigmented form:

- Lightly pigmented colloid islands are seen in the upper dermis.

Colloid degeneration (paracolloid):

- Amorphous, homogenized dermal collagen with less conspicuous clefts, extends deeply into the dermis.

- The material is relatively acellular, weakly PAS positive but negative with Congo red and crystal violet.

Hyaline - Value of a descriptive word in General Pathology and Dermatopathology


Further reading:

Colloid milium.

Colloid milium: A histopathologic mimicker of nodular amyloidosis.

Evaluation of colloid milium by in vivo reflectance confocal microscopy.

Adult colloid milium: a case report and literature review.

Unilateral colloid milium: a rare presentation.

Familial juvenile colloid milium: report of a well documented case.

Nodular amyloidosis: differentiation from colloid milium by electron microscopy.

Colloid milium: a review and update

Pigmented coalescing papules on the dorsa of the hands: pigmented colloid milium associated with exogenous ochronosis.

Juvenile colloid milium: clinical, histological and ultrastructural features.

Colloid milium: A histopathologic mimicker of nodular amyloidosis.





Dr Sampurna Roy  MD

Consultant  Histopathologist (Kolkata - India)







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