Colloid milium are benign skin lesions that may be confused with cutaneous amyloidosis. The clinical findings are important for making the diagnosis.
Clinical phenotypes:
(1) juvenile
(2) adult
(3) nodular
Risk factors for adult colloid milium:
(1) sun exposure
(2) chemical exposures (fertilizers, petroleum)
(3) drugs (hydroquinone)
Clinical features of adult colloid milium:
(1) lesions on sun-damaged skin, especially the face
(2) lesions are non-pruritic
(3) purpura are absent
A skin biopsy shows:
(1) small nodules of eosinophilic colloid material in the papillary dermis
(2) adjacent solar elastosis
(3) Grenz zone between lesion and epidermis
(4) Congo red, thioflavin T and immunostains for amyloid-P are often postive
Differential diagnosis:
(1) cutaneous amyloidosis
(2) nodular colloid degeneration
