Extensive colloid milium in a patient with chronic actinic dermatitis.

Abstract

Colloid milium is a rare and clinically underdiagnosed dermatosis, characterized by deposition of amorphous material in the dermis. Definitive diagnosis is established by histopathology which reveals the presence of colloid in dermal papillae. Photo-exposed areas are the most frequently involved sites and include dorsa of hands, neck, and ears. We present an adult man with an outdoor occupation who had longstanding chronic actinic dermatitis. For one and a half years he had been developing skin colored to slightly erythematous papules and nodules on his face, anterior neck, and dorsal aspect of the hands, symmetrically. These discrete lesions arose on the background of his eczematous sun exposed skin. Skin biopsy for histopathology of these papules showed deposition of amorphous colloid material in the dermal papillae with an uninvolved Grenz zone along with dermal solar elastoses. The coexistence of colloid milium with chronic actinic dermatitis in the same patient has not been previously reported in the medical literature even though both conditions are precipitated by chronic sun exposure. Similarly, such extensive lesions of colloid milium have rarely been reported and we ascribe this to his profession, compelling him to spend numerous hours in the sun every day.