Management of lentigo maligna (Hutchinson's melanotic freckle, in situ lentigo maligna melanoma) by regular observation relies on the detection of invasive melanoma before it has developed significant life-threatening potential. Recent studies indicate that lentigo maligna melanoma does not have a better prognosis than other forms of melanoma.
A case is reported of an amelanotic lentigo maligna that evolved from a macular lesion to a deeply invasive, amelanotic, lentigo maligna melanoma within 6 months. The melanoma was Clark level IV and measured 3.0 mm in maximum tumor thickness.
Observation of lentigo maligna at 6-month intervals would not seem to be sufficiently reliable in detecting the development of invasive lentigo maligna melanoma before it becomes a life-threatening disease. Early surgical excision is the treatment of choice.(Arch Dermatol. 1992;128:657-660)
Kelly JW. Following Lentigo Maligna May Not Prevent the Development of Life-Threatening Melanoma. Arch Dermatol. 1992;128(5):657-660. doi:10.1001/archderm.1992.01680150087012