A case of adult colloid milium with chronic sun exposure

A 57‐year‐old woman presented with a sudden onset of skin‐colored papules, mainly on the forehead ( Fig. 1), around the eyes, and on the dorsum of the hands ( Fig. 2). The papules had grown in number and size over 1 month. The papules were discrete, shiny, and dome‐shaped, varying in size between 1 and 5 mm. The patient was a farmer and had commonly been exposed to UV radiation in her work in the fields for a period of more than 45 years. She was fair‐skinned and admitted that she was reluctant to use sun protection during her outdoor work. No lesions were observed on the covered areas of the body. The diagnosis was uncertain and clinical differential diagnoses were those of primary cutaneous amyloidosis, senile sebaceous hyperplasia, adult colloid milium (ACM), and papular mucinosis. Figure 1 Skin‐colored papules on the forehead2Skin‐colored papules on the dorsum of the hand The patient was otherwise healthy and there was no history of similar lesions in her family. Results of routine laboratory investigations, including a complete blood count, blood chemistry, and urinalysis, were found to be within normal limits. Bence‐Jones proteinuria was not detected. Serum immunelectrophoresis examination revealed no abnormal finding. A punch biopsy specimen of the lesion stained with hematoxylin and eosin revealed subepidermal, eosinophilic, fissured amorphous masses abutting the epidermis without a grenz zone ( Fig. 3). The amorphous masses stained positive with periodic acid‐Schiff (PAS) both before and after diastase digestion. Negative staining was observed with Alcian blue at pH 2.5, Congo red, AE1/AE3, collagen type 4, and Thioflavine‐T. A diagnosis of ACM was made after clinicopathological correlation. 3Subepidermal, eosinophilic, fissured amorphous masses abutting the epidermis without a Grenz zone (hematoxylin and eosin stain, magnification × 52)