lentiginous

Lentiginous is a histopathologic term used in dermatology to describe a pattern of melanocytic proliferation that is confined to the dermoepidermal junction and arranged in a linear, single-cell-thick line along the basal layer. In this pattern, melanocytes are distributed along the base of the epidermis in a continuous or serpiginous row, often with elongation of the rete ridges. The term does not specify benign or malignant behavior by itself; it simply characterizes how the cells are growing.

This pattern can be seen in a range of conditions. Benign examples include lentigo simplex, solar lentigo, and junctional nevi, where the melanocytes along the basal layer may be increased but show little or no cytologic atypia or mitotic activity. In malignant or premalignant lesions such as lentigo maligna (in situ melanoma of chronically sun-damaged skin) and acral lentiginous melanoma, the same lentiginous arrangement can be present but with atypical melanocytes, nuclear atypia, increased mitotic figures, and possible invasion in advanced cases. The architectural pattern remains lentiginous, with proliferation concentrated along the basal layer, sometimes extending along adnexal structures.

Interpreting a lentiginous pattern requires clinical correlation and additional histologic features, including the presence or absence of cellular atypia, mitotic activity, and invasion. Thus, lentiginous describes a pattern rather than a single diagnosis, and its significance depends on the broader context of the lesion.