From the Guidelines
Lentiginous melanocytic proliferation with mild epidermal thickening is typically considered a benign condition, but it is crucial to evaluate any changing pigmented lesion by a dermatologist to rule out malignancy. This condition represents an increased number of melanocytes along the basal layer of the epidermis with some thickening of the skin's outer layer, and is commonly seen in conditions like solar lentigines (age spots or liver spots) or lentigo simplex. These lesions generally pose no risk of progression to melanoma, as noted in the context of lentigo maligna management 1. However, some atypical lentiginous proliferations can share features with early melanoma in situ, particularly lentigo maligna.
Key considerations for diagnosis and management include:
- Clinical criteria suggestive of malignancy, such as asymmetry, irregular borders, heterogeneous color, large diameter, and evolution (recent change) 2
- The use of epiluminescence microscopy (ELM) or dermatoscopy to improve the clinical diagnosis of pigmented lesions, although its accuracy depends on the experience of the dermatologist 2
- Complete excision with histopathological examination for suspicious lesions to assess all histological parameters and determine the thickness of the lesion and clearance of the margins 2
Given the potential for atypical lentiginous proliferations to resemble early melanoma, complete excision with histopathological examination is recommended for suspicious lesions. Regular skin examinations and sun protection are also advised for patients with multiple lentigines, as they may indicate increased sun damage and potentially higher risk for skin cancers. The histopathological report should include the diagnosis of the melanocytic nature of the lesion, confirmation of its malignancy, and other relevant parameters as outlined in consensus conferences 2.
From the Research
Lentiginous Melanocytic Proliferation
- Lentiginous melanocytic proliferation with mild epidermal hyperplasia (epidermal thickening) is not explicitly described as a benign condition in the provided studies 3, 4, 5, 6, 7.
- However, the studies suggest that lentiginous melanocytic proliferations can be associated with both benign and malignant conditions, such as solar lentigo and lentigo maligna, respectively 3, 4, 5, 6.
- A study found that lentiginous melanocytic proliferation was present in the epidermis adjacent to 75% of melanomas, suggesting a potential relationship between these proliferations and melanoma development 5.
- Another study noted that macromelanosomes, which are melanin-containing granules, were more frequently found in the margins of lentigo maligna than in solar lentigo, highlighting the importance of careful evaluation to distinguish between these entities 6.
Diagnostic Considerations
- The diagnosis of lentiginous melanocytic proliferations can be challenging, and the provided studies emphasize the importance of careful histopathologic evaluation and consideration of clinical factors, such as anatomic location and lesion characteristics 3, 4, 7.
- A study found that diagnostic change to melanoma occurred in 4.2% of cases initially diagnosed as atypical intraepidermal melanocytic proliferation, highlighting the need for thorough evaluation and potential re-excision 7.
- The presence of certain factors, such as anatomic location on the head and neck or acral areas, lesion extension to the base of the biopsy specimen, and melanoma in the initial biopsy's histopathologic differential diagnosis, may increase the risk of diagnostic change to melanoma 7.