PURPOSE: Nevus comedonicus is a rare disease involving abnormal development of the pilosebaceous unit, clinically appearing confluent clusters of open comedones. It is characterized by follicular epidermic invaginations filled with keratin, with atrophic pilose or sebaceous structures which are open to the lower pole of the invagination. We report a child with inflammatory pustules and cysts correlated to the nevus comedonicus. METHODS: A 15-month-old girl was referred for treatment of a nevus comedonicus that has been developed since birth. There were periodic episodes of erythema and swelling of the plaque. The patient had treated previously with retinoid cream for 2 weeks without obvious benefit at dermatology clinic. We excised the nevus comedonicus with Y-shape leaving some lesions. RESULTS: When we incised skin, we could see multiple large whitish cysts beneath the nevus comedonicus. Histopathologic findings showed deep invagination of epidermis filled with keratin plugs, keratinous cyst in the dermis, rudimentary hair follicle. CONCLUSION: We treated rare nevus comedonicus with multiple large cysts as surgical excision.