ridges and less within the furrows of the dermatoglyphs. Subsequent histopathologic analysis of those lesions demonstrated atypical melanocytes containing melanin granules within the crista profunda intermedia. 6 Similarly, in their retrospective analysis of Japanese patients with melanocytic lesions, Saida et al 5 found the parallel ridge pattern more diagnostically accurate of melanoma in situ than "irregular diffuse pigmentation." 5(p1235) Melanocytic nevi, subcorneal hemorrhage, exogenous pigmentation, and lentiginosis and drug-induced hyperpigmentation can demonstrate a dermoscopic parallel ridge pattern. 3 Benign dermoscopic attributes include a parallel furrow pattern, 5 a lattice-like pattern, 6 and/or the lack of disruption of the acrosyringia within the epidermal ridges. 3 Our patient's history suggested recent onset, an uncommon feature in ALM. Because we did not specifically inquire about exogenous pigment exposures, our initial evaluation failed to reveal information that may have allowed for earlier exclusion of ALM. Our case serves as a reminder to clinicians of the importance of a thorough history. Exogenous tissue dyeing should be considered in the differential diagnosis of acral pigmented lesions, particularly if the clinical history suggests the lesion is of recent onset.
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