Lentigo maligna – low magnification
LEGEND
Lentigo maligna is a melanoma in situ that occurs in chronically sun-exposed areas, most commonly on the face. Note the abundant presence of pilosebaceous units.
There is no evidence of melanocytes breaching the basement membrane.
It remains controversial how many of these lentigo maligna lesions may progress to invasive melanoma over time; the estimated percentage is probably low.
- Presence of solar elastosis
Intraepidermal lentiginous proliferation of melanocytes: This refers to a dense, horizontal, contiguous proliferation of atypical melanocytes, with only a few scattered nests (theques).
Lentigo maligna – high magnification
LEGEND
- Frequent extension of atypical melanocytes into adnexal structures, particularly into the follicular epithelium.
Lentigo maligna
LEGEND
Here’s another example
Abundant solar elastosis and pilosebaceous units, supporting the sun-exposed location of the lesion.
Intraepidermal lentiginous proliferation of melanocytes, meaning a dense, horizontal proliferation of atypical melanocytes with a few small nests, and frequent adnexal extension of these atypical melanocytes into the follicular epithelium.
Presence of melanophages in the dermis
Invasive melanoma of lentigo maligna subtype
LEGEND
Intraepidermal lentiginous proliferation of melanocytes, i.e., a dense horizontal proliferation of atypical melanocytes with some nests. A malignant dermal component was identified in this biopsy.
- Prominent solar elastosis
- Pagetoid spread, i.e., melanocytes migrating upward into the epidermis
- Melanophages in the dermis
Invasive melanoma of lentigo maligna subtype
LEGEND
SOX-10 helps in better identifying the invasive component, if present.
SOX-10 labels melanocyte nuclei, allowing improved visualization of pagetoid spread.
Invasive melanoma of lentigo maligna subtype
LEGEND
- Lentiginous intraepidermal proliferation of atypical melanocytes with occasional small nests
- Frequent adnexal extension of atypical melanocytes into the follicular epithelium
- Melanophages in the dermis
