We present a case of a 4-year-old fair-skinned girl, with no significant medical history, who presented to the outpatient clinic of an academic medical center with an asymptomatic, flesh-colored, cobblestoned plaque on her lateral left thigh (Fig 1). Per the family's report, the lesion had grown significantly since it was first noticed 2 years ago, with current measurements of 7.5 cm by 6.5 cm at the time of clinical presentation. The patient denied pain, tenderness, or pruritus at the site, and there was no history of drainage or infection. Further interrogation found no family history of cutaneous malignancies and no history of trauma to the area. The clinical differential diagnosis included lymphangioma, granuloma annulare, and scleromyxedema. Fig 1 Flesh-colored cobblestone plaque seen on left thigh. Healing biopsy site is visible near the center of the lesion. An incisional biopsy of the lesion was performed after obtaining informed consent from the patient's mother. Sections showed increased mucin, highlighted by alcian blue stains, confined to the dermis. The subcutis was normal (Fig 2). There was no evidence of abnormal lymphatic pattern or interstitial histiocytes. A diagnosis of cutaneous mucinosis of infancy (CMI) was made. The patient and her family were assured of the benign nature of CMI. She will be monitored for any acute changes to the lesion, but she is not being treated with any pharmacologic intervention or further surgical action at this point. Fig 2 Sections show a subtle thickening of the reticular dermis with widening of the interstitial spaces, seen in low power (A) and high power (B). C, Alcian blue stains highlight the increased mucin.