Simple Summary
Blue-black nodules of the digits can be difficult to diagnose because benign conditions may closely resemble melanoma and other skin tumors. We describe a 64-year-old man with a blue nodule on the left fifth digit at the site of a pencil injury sustained during childhood. After remaining asymptomatic for decades, the lesion gradually enlarged over three years. Biopsy showed coarse dark pigment surrounded by multinucleated giant cells and fibrosis, with no melanocytic proliferation, confirming a graphite foreign-body granuloma. Retained pencil-core material can therefore produce a delayed tissue reaction long after the original injury has been forgotten. This case highlights the value of asking about remote trauma when evaluating an unexplained pigmented lesion while also emphasizing that a changing lesion should still be biopsied when melanoma or another neoplasm cannot be excluded clinically.
Abstract
Background/Objectives: Pigmented lesions arising at sites of remote trauma can create diagnostic uncertainty when their clinical appearance overlaps with melanocytic neoplasms. This report describes a graphite foreign-body granuloma presenting decades after a childhood pencil injury and highlights the importance of distinguishing exogenous pigment from melanocytic proliferation. Methods: A 64-year-old man presented with an asymptomatic 6-mm blue dermal nodule on the left fifth digit at the site of a penetrating pencil injury sustained during childhood. After remaining unchanged for decades, the lesion gradually enlarged over three years and produced mild nail plate deformity without periungual or subungual pigmentation. Cellular blue nevus, nodular melanoma, and graphite foreign-body granuloma were considered. A shave biopsy was performed, followed by histopathologic examination. Results: The biopsy revealed a well-demarcated intradermal lesion containing abundant dark amorphous pigment and sclerosis. Higher-power examination demonstrated coarse granular black pigment associated with multinucleated giant cells and surrounding fibrosis, without melanocytic proliferation. These findings established the diagnosis of graphite foreign-body granuloma. Conclusions: Retained graphite may produce a delayed foreign-body reaction and become clinically concerning many years after implantation. Because its clinical features may overlap with melanoma and other pigmented tumors, a history of remote trauma can refine the differential diagnosis but cannot replace tissue examination. Histopathologic evaluation remains essential for definitively distinguishing exogenous pigment from melanocytic proliferation.