Classically, lentigo maligna (LM) may be present for years before it demonstrates dermal invasion and becomes LM melanoma (LMM). Follicular melanoma (FM) is a rare form of melanoma distinguished from LMM by having shorter duration and much smaller lesions (<0.5 cm in diameter) that are relatively symmetric.1
An asymmetric, 0.3-cm, brown macular lesion was observed on the nose of a 61-year-old man, who reported that the lesion was present for 1 year. Follicular openings were surrounded by a rim of hyperpigmentation. One asymmetric follicular opening and 1 rhomboidal structure were seen dermoscopically. The clinical diagnosis of LM seemed reasonable, and excision was recommended. However, the patient did not follow the recommendation. He returned 8 months later with an enlarged (0.5-cm) and darker lesion with apparent homogeneous areas and clearly obliterated hair follicles on dermoscopy (Figure 1).
Kilinc-Karaarslan I, Akalin T, Ozdemir F. Lentigo Maligna Melanoma With Folliculotropism: Dermoscopic Features During Rapid Progression. Arch Dermatol. 2009;145(6):725-726. doi:10.1001/archdermatol.2009.101