A 54-year old woman had crashed a pencil into her right palm when she was an elementary school student. A bluish flat lesion was left without any symptoms. However, the lesion had recently become elevated. Ultrasonography revealed a 15 x 11 mm hypoechoic tumor, with a 10 mm hyperechoic linear material inside the tumor, characteristic features of a pencil-core granuloma. The tumor was surgically removed and a pencil core was found inside the tumor. Histologic examination showed a fibrotic granuloma with dark pigmented granules that is consistent with pencil-core granuloma. As the clinical presentation of pencil-core granuloma is sometimes similar to malignant melanoma, ultrasonographic imaging may be a useful tool for an accurate diagnosis.
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