Histologic distinction between subungual lentigo and melanoma.
ABSTRACT The distinction between a benign subungual pigmented macule (lentigo) and an early lesion of melanoma in situ can be difficult. To identify histologic parameters of potential diagnostic value, we retrospectively reviewed biopsies and excisions of 35 pigmented nail lesions. We studied 20 melanomas (10 invasive and 10 noninvasive) and 15 benign subungual melanotic lentigines. Ten specimens of normal nail apparatus obtained for reasons other than melanonychia were also examined as controls. The parameters, which were analyzed, included the density of melanocytes, the presence of multinucleated cells, pagetoid spread, cytologic atypia, inflammation, and the distribution of melanin pigment. The density of melanocytes was measured as the number of cells per 1 mm stretch of subungual dermo-epithelial junction [=melanocyte count (MC)]. The MC for invasive melanomas was as follows: mean=102, median=92.5, and range 52 to 212. For noninvasive (only in situ) melanoma, the mean MC was 58.9, median 51, and range 39 to 136. For benign subungual melanotic macules, the mean MC was 15.3, median 14, and range 5 to 31. In normal controls, the mean MC was 7.7, median 7.5, and range 4 to 9. Qualitative features associated with in situ melanoma and useful for its distinction from benign subungual melanotic macules included the presence of confluent stretches of solitary units of melanocytes, multinucleated melanocytes, lichenoid inflammatory reaction, and florid pagetoid spread of melanocytes.
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ABSTRACT: Background For longitudinal melanonychia, clinical and dermoscopic criteria for differentiating malignant melanoma in situ from benign nevus/lentigo/functional melanonychia have not been fully established.Objective To propose a clinical classification of longitudinal melanonychia that is useful in judging the need for follow-up.MethodsA total of 137 patients with longitudinal melanonychia referred to our outpatient clinic in the most recent eight years were included. The mean and median lengths of follow-up for patients were 5.0 and 5.5 years, respectively. We classified the 137 lesions into three types by clinical and dermoscopic features of the nail and periungual skin, including Hutchinson sign, variation of color, and borders in the pigmentation band. We observed type I and II lesions with dermoscopy every six months and three months, respectively.ResultsAfter follow-up, all 72 lesions classified as type I were thought to be benign nevus/lentigo/functional melanonychia. Five of the 52 lesions classified as type II showed enlargement during follow-up, and biopsy was performed. Of these five lesions, three were diagnosed as nevus/lentigo, and the other two were diagnosed as malignant melanoma in situ. All 13 lesions classified as type III were diagnosed as malignant melanoma in situ.Conclusion We can expect a type I lesion to be a benign nevus/lentigo/functional melanonychia and a type III lesion to be a malignant melanoma in situ; however, type II lesions fall in a gray zone. We believe this classification is useful in deciding treatment and follow-up.International journal of dermatology 05/2014; 53(5). DOI:10.1111/ijd.12001 · 1.23 Impact Factor
Article: Histopathology of the nail unit.[Show abstract] [Hide abstract]
ABSTRACT: In this report, we review several inflammatory infectious and tumoral conditions of the nail unit. We emphasize the anatomic peculiarities of such pathologies of the nail unit and provide some required diagnostic criteria.
Article: Longitudinal melanonychias[Show abstract] [Hide abstract]
ABSTRACT: Melanonychia is black or brown pigmentation that appears in the fingernails and toenails. The pigment can come from exogenous sources, such as bacteria or fungal infection, tar, or blood. Endogenous causes include aberrant melanin production in the nail bed, resulting in a longitudinal presentation. Melanonychia can indicate the presence of cancerous growths, as well as infection. Diagnostic measures, including dermatoscopy, biopsy, and histopathology, can determine the cause and direct the course of treatment. Malignant lesions should be excised, and underlying infections should be addressed with antibiotics or antifungals. Benign lesions and hyperpigmentation may benefit from a wait-and-see approach.Clinics in dermatology 09/2013; 31(5):594-601. DOI:10.1016/j.clindermatol.2013.06.007 · 3.11 Impact Factor