Surgical treatment of lentigo maligna and lentigo maligna melanoma

Lentigo maligna (LM) is well known as an irregularly pigmented macular lesion usually presenting on the sun-damaged head and neck of older patients. Lentigo maligna (LM) has the potential to develop into invasive melanoma (LMM). A method of surgical excision for the treatment of LM and LMM using paraffin sections with tissue mapping to ensure clear margins before delayed defect closure is described. The results of applying this method in the treatment of 66 cases over a 40 month period are presented. Thirty-eight per cent of cases required two excisions or more to clear the tumour and 32% of cases showed evidence of invasive melanoma. Only one case has recurred thus far, and none have developed metastatic disease.     

Lentigo maligna and lentigo maligna melanoma

Lentigo maligna (LM) is a pigmented lesion that occurs on the sun-exposed skin, particularly the head and neck areas, of an older patient. The lesion increases in size and at some point, often many years after its onset, may become lentigo maligna melanoma (LMM). For this reason, most authors consider LM a form of melanoma in situ. Treatment includes surgical or destructive modalities; the preferred form of therapy is surgical removal. Histopathologic features include a proliferation of atypical melanocytes along the basal layer of the epidermis and adnexal structures. This article discusses the clinical, histopathologic, and epidemiologic features of LM. The prognosis and treatment of LM are reviewed. Although the lifetime risk of the development of LMM is unclear, LMM is discussed briefly.     

The risk of progression of lentigo maligna to lentigo maligna melanoma

An analysis is presented which estimates the risk of progression of lentigo maligna (LM) to lentigo maligna melanoma (LMM) in U.S. whites using three data sources: the Health and Nutrition Examination Survey I for estimation of the age-specific prevalence of LM; the Surveillance, Epidemiology, and End Results Program for estimation of the age-specific incidence of melanoma; and the data from three melanoma registries for estimation of the age-specific case fraction of LMM among all invasive melanomas. The risk varies with age and is likely to be greater than estimated here for patients who present themselves for evaluation of changes in a lesion of LM. Our analysis suggests that the risk of progression from LM to LMM is substantially lower than is commonly believed.     

Recurrent lentigo maligna as amelanotic lentigo maligna melanoma

Amelanotic lentigo maligna and lentigo maligna melanoma are extremely rare tumours. Even rarer is a recurrent amelanotic lentigo maligna or amelanotic lentigo maligna melanoma at the site of a previously removed pigmented lentigo maligna. We describe two cases of recurrent amelanotic lentigo maligna melanoma manifesting as erythematous plaques evolved from previously excised pigmented lentigo maligna.     

Microinvasive lentigo maligna melanoma

Ninety-one skin biopsy specimens previously identified as lentigo maligna were examined for the presence of microinvasion, using the demonstration of S100 protein within atypical cells as the means for locating these superficial foci. In 14 cases, atypical melanocytes were identified, most often in the papillary dermis. The mean depth of invasion in this group was 0.23 mm with a range of 0.10 mm to 0.75 mm. In these cases, atypical cells were difficult if not impossible to identify in routinely processed sections, either because the invasive cell was a spindle cell variant and indistinguishable from a fibrohistiocytic cell, because the invasive cells were occasionally solitary or in small groups, or because there was an inflammatory infiltrate that obscured the tumor cells. Recent studies of lentigo maligna melanoma have revealed no better prognosis when compared to that of other forms of malignant melanoma after normalization for depth and body location. We therefore advocate close examination of lentigo maligna with the use of appropriate immunohistochemical techniques if there are areas of dermal fibrosis or inflammation that might obscure invasion.     

Fractionated radiotherapy of lentigo maligna and lentigo maligna melanoma in 64 patients

Between 1987 and 1998, 64 patients with lentigo maligna (LM) (n = 42) or lentigo maligna melanoma (LMM) (n = 22) were treated by fractionated radiotherapy. In all 22 patients with LMM, excision of the nodular part of the LMM was performed before radiation of the residual lentiginous tumor. During the follow-up period of 1 to 96 months (mean, 23 months; median, 15 months), none of the 42 patients with LM displayed any signs of recurrence of LM after radiation therapy alone. Of the 22 patients with LMM, only 2 patients showed local recurrence of the tumor, salvaged by excision in both cases. One patient with LMM suffered from metastatic disease without local recurrence of the melanoma 44 months after radiation therapy. The cosmetic results of radiotherapy were good or excellent in the vast majority of patients, with only a few experiencing hypopigmentation or hyperpigmentation in the irradiated area. Fractionated radiation therapy with superficial x-rays is an effective method of treatment of LM associated with low morbidity and leading to clinical results comparable to those of surgical excision.     

Pagetoid malignant melanoma and lentigo maligna melanoma of toe

Summary Two cases of malignant melanoma on the toe of middle-aged women were examined chiefly by the fluorescence method of Falck and Hillarp. In one of the patients, histopathology of the pigmented tumor on the left middle toe was a Pagetoid (superficial spreading) melanoma in situ, and the subungual granulomatous lesion on the right great toe in the other patient was a lentigo maligna melanoma. On fluorescence microscopy, characteristic findings of the pigment cells lying in the epidermis of both types may be summarized as follows: In the Pagetoid melanoma, the melanoma cells are ovoid, lack dendritic processes, and emit specific yellow fluorescence. In the lentigo maligna melanoma, the pigment cells clearly show dendritic processes, and emit specific green fluorescence.     

Surgical margins for lentigo maligna and lentigo maligna melanoma: the technique of mapped serial excision

OBJECTIVES: To assess the margins required for excision of lentigo maligna (LM) and lentigo maligna melanoma (LMM) by the technique of mapped serial excision (MSE), and to assess the efficacy of MSE. DESIGN: An interventional, prospective, noncontrolled case series. SETTING: Tertiary referral, dermatologic surgery unit. PATIENTS: Consecutive patients with head and neck LM or LMM who underwent MSE between March 1, 1993, and October 31, 2002. INTERVENTION: The MSE of LM or LMM. MAIN OUTCOME MEASURES: The number of 5-mm levels for excision of LM and LMM and recurrence. RESULTS: One hundred sixty-one LMs or LMMs in 155 patients were treated. Thirty percent (37 of 125) of LMs required more than 5-mm margins. For LMMs less than 1 mm in Breslow thickness, 12% (4/32) required more than 10-mm margins. For primary tumors, 20% of LMs (18 of 91) required more than 5-mm margins, while 10% of LMMs less than 1 mm in Breslow thickness (2 of 21) required more than a 10-mm margin. For recurrent tumors, 56% of LMs (19/34) required more than a 5-mm margin. Mean follow-up of 38 months (range, 5-100 months) showed 4 recurrences (2%) after MSE. The extrapolated recurrence at 5 years was 5.0%. CONCLUSIONS: The current recommendations of 5-mm margins for LM and 10-mm margins for LMM less than 1 mm in Breslow thickness are often insufficient. Our results demonstrate the importance of margin-controlled excision, particularly in recurrent lesions. The use of MSE offers a high cure rate, in conjunction with tissue conservation.     

Extrafacial lentigo maligna melanoma: analysis of 71 cases and comparison with lentigo maligna melanoma of the head and neck

We report a retrospective analysis of extrafacial lentigo maligna melanoma (LMM), and a comparison with patients with LMM of the head and neck. Seventy-one patients (22 men, 49 women) with extrafacial LMM were identified from the Scottish Melanoma Group database for January 1979–March 1996. Their mean age (63 years) was significantly less than that of 335 patients with head and neck LMM (mean 72 years, P < 0.001), with a significantly greater difference among women than men. Extrafacial sites comprised 17.5% of LMMs. There was a marked body site distribution difference between the sexes (P = 0.001): 68% of extrafacial LMMs in men were on the trunk while 80% in women were on the limbs, particularly the lower leg. Extrafacial LMMs were thinner at presentation than head and neck LMMs (P < 0.05) in both sexes, but this was not simply explained by the younger age of these patients as there was no significant correlation between age and tumour thickness at either extrafacial or at head and neck sites. Although the female lower leg is a site of chronic solar exposure in older women, the other extrafacial sites are habitually covered in the temperate Scottish climate. The significantly younger age group of patients with LMM at extrafacial compared with head and neck sites therefore suggests that the relationship between LMM and sunlight is not simply related to cumulative solar exposure. The demonstration that head and neck LMMs were thicker at presentation compared with extrafacial sites, despite being at a more routinely visible part of the body, suggests that there are still opportunities for targeted pigmented lesion public education.