A 67-year-old woman sought treatment for a painful nodule on the perionychium of the right second finger that had rapidly enlarged over the previous year. The patient reported that the point of a lead pencil had become lodged in her skin at the age of 10 years. The nodule was blue-gray in color, 9.6 mm in maximum diameter, and unattached to the subcutaneous tissue (Fig 1). Dermoscopic examination found homogeneous blue pigmentation (HBP) over the lesion. Several dotted vessels were observed in the lesion center under higher magnification (Fig 2). Histologic findings confirmed a diagnosis of pencil-core granuloma (Fig 3).Key messageThis case displayed HBP by dermoscopy that resembled a blue nevus. HBP generally corresponds to dermal melanin granules of melanocytic tumors, such as blue nevus, but is also observed in hemangioma, dermatofibroma, and other nonmelanocytic tumors.1Longo C. Scope A. Lallas A. et al.Blue lesions.Dermatol Clin. 2013; 31: 637-647Abstract Full Text Full Text PDF PubMed Scopus (21) Google Scholar Histopathologic examination found that the HBP in this case was caused by the dermal deposition of graphite and graphite accumulation within macrophages. Several cases of pencil-core granuloma have been reported to exhibit HBP on dermoscopy,2Menzies S.W. Moloney F.J. Byth K. et al.Dermoscopic evaluation of nodular melanoma.JAMA Dermatol. 2013; 149: 699-709Crossref PubMed Scopus (76) Google Scholar with a history of embedded pencil-tip graphite at the site representing a clue for correct diagnosis. However, melanoma could not be completely excluded in this case because of the dermoscopic finding of dotted vessels and the rapid size increase of the tumor. Close attention is necessary for nodular melanoma, as it frequently shows a symmetrical pigmentation pattern without pigment network.2Menzies S.W. Moloney F.J. Byth K. et al.Dermoscopic evaluation of nodular melanoma.JAMA Dermatol. 2013; 149: 699-709Crossref PubMed Scopus (76) Google Scholar Pencil-core granulomas may suddenly develop long after the initial trauma, presumably because of delayed granulomatous reactions towards the graphite, clay, wax, and other components of pencil cores.3Terasawa N. Kishimoto S. Kibe Y. Takenaka H. Yasuno H. Graphite foreign body granuloma.Br J Dermatol. 1999; 141: 774-776Google Scholar This case displayed HBP by dermoscopy that resembled a blue nevus. HBP generally corresponds to dermal melanin granules of melanocytic tumors, such as blue nevus, but is also observed in hemangioma, dermatofibroma, and other nonmelanocytic tumors.1Longo C. Scope A. Lallas A. et al.Blue lesions.Dermatol Clin. 2013; 31: 637-647Abstract Full Text Full Text PDF PubMed Scopus (21) Google Scholar Histopathologic examination found that the HBP in this case was caused by the dermal deposition of graphite and graphite accumulation within macrophages. Several cases of pencil-core granuloma have been reported to exhibit HBP on dermoscopy,2Menzies S.W. Moloney F.J. Byth K. et al.Dermoscopic evaluation of nodular melanoma.JAMA Dermatol. 2013; 149: 699-709Crossref PubMed Scopus (76) Google Scholar with a history of embedded pencil-tip graphite at the site representing a clue for correct diagnosis. However, melanoma could not be completely excluded in this case because of the dermoscopic finding of dotted vessels and the rapid size increase of the tumor. Close attention is necessary for nodular melanoma, as it frequently shows a symmetrical pigmentation pattern without pigment network.2Menzies S.W. Moloney F.J. Byth K. et al.Dermoscopic evaluation of nodular melanoma.JAMA Dermatol. 2013; 149: 699-709Crossref PubMed Scopus (76) Google Scholar Pencil-core granulomas may suddenly develop long after the initial trauma, presumably because of delayed granulomatous reactions towards the graphite, clay, wax, and other components of pencil cores.3Terasawa N. Kishimoto S. Kibe Y. Takenaka H. Yasuno H. Graphite foreign body granuloma.Br J Dermatol. 1999; 141: 774-776Google Scholar