A case of clear cell acanthoma presenting as nipple eczema

S ir, Clear cell acanthoma is a relatively uncommon benign epidermal tumour, which usually presents as solitary, rarely multiple tumours, often localized on the lower legs of middle aged or elderly individuals. 1 Clear cell acanthoma presents as a flat or dome‐shaped, sharply demarcated papule or nodule, sometimes with a keratotic scale in bright red or pink colour, which make the tumour appear as a vascular lesion. 2 We report a case of clear cell acanthoma presenting as nipple eczema in a patient with atopic dermatitis. A 23‐year‐old Korean woman presented with a 3‐month history of a pruritic, irregular bordered, brownish plaque on the left nipple ( Fig. 1a). Previously, she had been treated intermittently for atopic dermatitis in private dermatologic clinics. Her family history was non‐contributory. As the lesion showed the clinical appearance of nipple eczema, she was treated with a systemic and topical steroid for 2 weeks without any clinical improvement. A skin biopsy was done, and histopathological findings showed parakeratosis, sharply demarcated acanthosis composed of clear cells, regular elongation of rete ridges in the epidermis (Fig. 1b). The clear cells had bright cytoplasm and normal nuclei. Clear cells stained positively to the periodic acid‐Schiff (PAS) reaction, which was diastase‐labile, indicating the presence of glycogen. Electron microscopy showed many intracytoplasmic glycogen granules.