Reticulated black solar lentigo ('ink spot' lentigo)
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1Department of Dermatology, Yale University School of Medicine, New Haven, Conn.
Background And Design:
Pigmented lesions that are black and have an irregular outline are often considered suspicious for melanoma; however, these features may be seen in benign lesions. The reticulated black solar lentigo is such a lesion and is described in a clinicopathologic study of nine lesions in eight patients.
Results:
The "ink spot" lentigo is distinguished clinically by its color and wiry or beaded, markedly irregular outline. It has a reticulated pattern and most resembles a spot of ink on the skin. In this series of patients, the lesions were limited to sun-exposed areas of the body and had a distribution pattern similar to that of solar lentigines. Although all the patients were of Celtic ancestry and had numerous solar lentigines, they usually had only one black lentigo (range, one to four; mean, 1.6; median, one). Histologic evaluation, including electron microscopy and dopa-incubated vertical sections, demonstrated lentiginous hyperplasia of the epidermis, marked hyperpigmentation of the basal layer with "skip" areas that involved the rete ridges, and a minimal increase in the number of melanocytes.
Conclusions:
Because of their dark color, irregular border, and limited number, reticulated black solar lentigines were of concern to patients and primary care physicians. However, the characteristic features of these lesions allow one to make the clinical diagnosis of a benign lentigo.
Insights
Reticulated black solar lentigo, often mistaken for melanoma due to its dark color and irregular outline, is a benign skin lesion. Clinicopathologic study confirms its distinct features, aiding accurate diagnosis.
Area of Science:
- Dermatopathology
- Dermatology
- Oncology
Background:
- Pigmented lesions with irregular, dark borders can be concerning for melanoma.
- Reticulated black solar lentigo presents with these suspicious features but is benign.
Observation:
- The "ink spot" lentigo exhibits a reticulated pattern and wiry, irregular outline.
- Lesions appear on sun-exposed skin, similar to solar lentigines, and are typically few in number.
- Histology reveals epidermal hyperplasia, basal layer hyperpigmentation with skip areas, and minimal melanocyte increase.
Findings:
- Clinicopathologic study of nine lesions in eight patients characterized the "ink spot" lentigo.
- Histologic evaluation, including electron microscopy, confirmed benign features.
- The lesions, despite concerning clinical appearance, showed benign histopathologic findings.
Implications:
- Accurate clinical diagnosis of reticulated black solar lentigo is possible based on characteristic features.
- Distinguishing this benign lentigo from melanoma prevents unnecessary patient anxiety and invasive procedures.
- Understanding these benign lesions improves diagnostic accuracy in pigmented skin conditions.