Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content + Patient Story Download Section PDF Listen ++ A 65-year-old woman noted that a brown spot on her face was growing larger and darker (Figure 168-1). A broad shave biopsy showed lentigo maligna (LM) (melanoma in situ). The patient was referred for Mohs surgery for definitive treatment. ++Figure 168-1Graphic Jump LocationView Full Size||Download Slide (.ppt)Lentigo maligna (melanoma in situ) on the face. (With permission from Usatine RP, Moy RL, Tobinick EL, Siegel DM. Skin Surgery: A Practical Guide. St. Louis, MO: Mosby; 1998.) + Introduction Download Section PDF Listen ++ LM begins as a tan-brown macule melanoma usually in sun-damaged areas of the skin in older individuals. It is a subtype of melanoma in situ. + Synonyms Download Section PDF Listen ++ Hutchinson melanotic freckle. + Epidemiology Download Section PDF Listen ++ The incidence of LM is directly related to sun exposure. In the United States, the incidence is greatest in Hawaii, intermediate in the central and southern states, and lowest in the northern states.1Generally, patients with LM are older than age 40 years, with a peak incidence between the ages of 65 and 80 years.2Persons with LM melanoma (LMM) tend to be older, fair-skinned persons with markers of actinic skin damage and prior skin cancers, and the incidence is increasing.3The lesions occur more commonly on the driver's side of the head and neck in men in Australia.4 + Etiology and Pathophysiology Download Section PDF Listen ++ LM is a subtype of melanoma in situ, a preinvasive lesion confined to the epidermis (Figures 168-1, 168-2, and 168-3). It is caused by cumulative sun exposure and, therefore, seen later in life.LMM occurs when the lesion extends into the dermis (Figure 168-4). LM can be present for long periods (5 to 15 years) before invasion occurs, although rapid progression within months has been described.5The risk for progression to LMM appears to be proportional to the size of the lesion of LM.5 ++Figure 168-2Graphic Jump LocationView Full Size||Download Slide (.ppt)LM on the face, presenting as a single large evolving pigmented lesion with changing color. (With permission from Usatine RP, Moy RL, Tobinick EL, Siegel DM. Skin Surgery: A Practical Guide. 1998, St. Louis: Mosby.) ++Figure 168-3Graphic Jump LocationView Full Size||Download Slide (.ppt)LM on the ear (melanoma in situ). (With permission from Usatine RP, Moy RL, Tobinick EL, Siegel DM. Skin Surgery: A Practical Guide. St. Louis, MO: Mosby; 1998.) ++Figure 168-4Graphic Jump LocationView Full Size||Download Slide (.ppt)LMM on the cheek. This lesion is invasive and no longer melanoma in situ. A partial broad scoop shave biopsy is a good way to make this diagnosis, as a full depth complete excisional biopsy would be prohibitively large and a punch biopsy might miss the diagnosis. (Courtesy of the Skin Cancer Foundation. For more information www.skincancer.org.) + Risk Factors Download Section PDF Listen ++ UV radiation exposure: risk increases with increased hours of exposure to sunlight, with the amount of actinic damage, and with a history of nonmelanoma skin cancer.Increased number of melanocytic nevi, including large or giant congenital nevi.Fair skin.History of severe sunburns.Porphyria cutanea tarda.Tyrosine-positive oculocutaneous albinism.Xeroderma pigmentosum.Occupational risk with sun exposure. + Diagnosis Download Section PDF Listen +++ Clinical Features ++ Large pigmented patch with multiple colors, including brown, black, pink, and white (signifying regression) (Figures 168-1, 168-2, and 168-3).May have ill-defined borders and microscopic extension that can determine the clinical borders and complete removal of the lesion difficult.One retrospective study revealed the four most important features of LM: asymmetric pigmented follicular openings, dark rhomboidal structures, slate-gray globules, and slate-gray dots with a sensitivity of 89% and a specificity of 96% (see Appendix C, Dermoscopy).6 +++ Typical Distribution ++ Face, head, and neck. There is a predilection for the nose and cheek (Figures 168-1 and 168-2). +++ Biopsy ++ Complete excisional biopsy is rarely practical because these lesions are frequently large and are on the face (Figure 168-1). There is debate in the literature between doing broad shave biopsy, multiple punch biopsy, and incisional biopsy.7 The goal is to avoid sampling error and misdiagnosing a LM or LMM as a benign lesion.A lesion suspicious for LM or LMM can be biopsied using a broad scoop shave biopsy approach with a Derma blade or sharp razor blade (Figure 168-4).7 The goal is to sample the dermal-epidermal junction and still produce a good cosmetic result (especially if the lesion turns out to be benign).One option is multiple smaller biopsy samples of each morphologically distinct region of the lesion.7If an area suspicious for invasion is noted, or if there is an area of induration suspicious for associated desmoplastic melanoma, a deeper incisional biopsy of this area should be performed.7If sampling is incomplete, the presence of a solar lentigo, pigmented actinic keratosis, or reticulated seborrheic keratosis (SK) could mislead the pathologist and clinician to the wrong conclusion that the incisional specimen is representative of the whole, and that no LM is present.7In a study of LM, contiguous pigmented lesions were present in 48% of the specimens obtained by broad shave biopsy or Mohs surgery. The most common lesion was a benign solar lentigo (30%), followed by pigmented actinic keratosis (24%).7 This should be kept in mind when interpreting biopsy results to avoid false negatives. + Differential Diagnosis Download Section PDF Listen ++ Solar lentigo—These hyperpigmented patches are very common on the faces and the dorsum of the hands of persons with significant sun exposure and the incidence increases with age. A possible solar lentigo is more suspicious for LM or LMM when it is larger, more asymmetric, has irregular borders and has more variation in colors. Pigmented lesions with these characteristics should be biopsied to determine the correct diagnosis. Many fair-skinned individuals have a number of solar lentigines making this a challenge. The use of dermoscopy and judicious biopsies is necessary to avoid missing LM and LMM (Figures 168-5 and 168-6). SKs are ubiquitous benign growths that occur more frequently with age. An early SK can be flat and easily resemble a solar lentigo or LM. The SKs on the back are less likely to be confused for LM, but a large flat SK on the face can easily be mistaken for a LM. More importantly, avoid missing a LM because it is assumed to be a flat early SK. When in doubt, biopsy the lesion with a quick and easy shave biopsy. Do not freeze a possible SK unless you are sure that it is truly benign (see Chapter 158, Seborrheic Keratosis).LMM is the feared outcome of missing an LM and not treating it properly. Any suspicious lesion requires biopsy. Don't be afraid to do a quick and easy shave biopsy rather than a full-thickness excision. If it turns out to be a LM or LMM, you can refer for definitive treatment and your biopsy technique does not change the prognosis. Early diagnosis does. LMM accounts for 4% to 15% of cutaneous melanoma (Figure 168-4) (see Chapter 172, Melanoma). ++Figure 168-5Graphic Jump LocationView Full Size||Download Slide (.ppt)Solar lentigo on the face of a middle-aged Hispanic woman. (Courtesy of Richard P. Usatine, MD.) ++Figure 168-6Graphic Jump LocationView Full Size||Download Slide (.ppt)Dermoscopy of the solar lentigo in the previous figure. The moth-eaten appearing edges are typical of a solar lentigo. There are no suspicious patterns and a shave biopsy confirmed that it was benign. (Courtesy of Richard P. Usatine, MD.) + Management Download Section PDF Listen ++ Therapy is directed toward preventing progression to invasive LMM. +++ Nonsurgical ++ Nonsurgical therapy for primary cutaneous melanomas should only be considered when surgical excision is not possible.Alternatives to surgery include topical imiquimod, cryosurgery, and observation. Efficacy of nonsurgical therapies for LM has not been fully established.8 SOR C +++ Medications ++ Topical imiquimod 5% cream has been described in multiple studies to be effective in treating LM, especially in patients who are not surgical candidates. It is an immune response modifier that is indicated for the treatment of actinic keratosis and superficial basal cell carcinomas. Studies are limited by highly variable treatment regimens and lack of long-term follow-up.8-10 SOR B +++ Surgical ++ For melanoma in situ, wide excision with 0.5- to 1.0-cm margins is recommended. For LM histologic subtype may require larger than 0.5-cm margins to achieve histologically negative margins, because of characteristically broad subclinical extension.8,10 SOR AStandard therapy is margin controlled surgical excision with Mohs surgery or rush permanent sections.10,11 SOR BThe perimeter technique is a method of margin-controlled excision of LM with rush permanent sections. The main advantage is that all margins are examined with permanent sections. The main drawback is that multiple operative sessions are required to complete the procedure.12Recommended margins for standard excision of melanoma in situ are 0.5 cm. This margin is often inadequate for LM because of the subclinical extension that can occur.10 The average margin required to clear LM in 90% to 95% of cases in one study was greater than 0.5 cm.11 Consequently, margin-controlled excision of LM is recommended.11 SOR BCryosurgery may be used in patients who are not good surgical candidates. In a study of 18 such patients with LM, the lesions resolved clinically in all cases, with no recurrence or metastasis detected during a mean follow-up of 75.5 months.13 SOR C These patients were treated with two freeze-thaw cycles of liquid nitrogen under local anesthesia in a single sitting. + Prevention Download Section PDF Listen ++ Because LMM is related to a lifetime of exposure to UV radiation, patients should limit sun exposure, especially between 10 am and 4 pm. When in the sun, make sure to wear sunscreen with a high sun-protection factor (SPF) that blocks both UVA and UVB. It's also a good idea to protect skin by wearing a broad-brim hat and clothing that covers your arms and legs. + Prognosis Download Section PDF Listen ++ There is a 5% estimated lifetime risk of developing LMM in patients diagnosed with LM at age 45 years.5 + Follow-Up Download Section PDF Listen ++ The National Comprehensive Cancer Network recommends that patients have regular clinical skin examinations at least yearly by their family physician or a dermatologist.14Regional lymph nodes should also be examined. + Patient Education Download Section PDF Listen ++ Patients diagnosed with LM need to minimize sun exposure and do regular self-skin examinations. +++ Patient Resources ++ Medline Plus. Melanoma—http://www.nlm.nih.gov/medlineplus/melanoma.html. +++ Provider Resources ++ The Skin Cancer Foundation. Melanoma—1-800-SKIN-490 or http://www.skincancer.org.National Cancer Institute. Melanoma—http://www.cancer.gov/cancertopics/types/melanoma.Dermoscopy. A website on dermoscopy to learn how to improve early diagnosis of melanoma—http://www.dermoscopy.org/. + References Download Section PDF Listen ++1. Clark WH Jr, Mihm MC Jr. Lentigo maligna and lentigo-maligna melanoma. Am J Pathol. 1969;55(1):39-67. [PubMed: 5776171] ++2. Cohen LM. Lentigo maligna and lentigo maligna melanoma. J Am Acad Dermatol. 1995;33(6):923-936. [PubMed: 7490362] ++3. Swetter SM, Boldrick JC, Jung SY, et al. Increasing incidence of lentigo maligna melanoma subtypes: northern California and national trends 1990-2000. J Invest Dermatol. 2005;125(4):685-691. [PubMed: 16185266] ++4. Jelfs PL, Giles G, Shugg D, et al. Cutaneous malignant melanoma in Australia, 1989. Med J Aust. 1994;161(3):182-187. [PubMed: 8035720] ++5. Weinstock MA, Sober AJ. The risk of progression of lentigo maligna to lentigo maligna melanoma. Br J Dermatol. 1987;116 (3):303-310. ++6. Schiffner R, Schiffner-Rohe J, Vogt T, et al. Improvement of early recognition of lentigo maligna using dermatoscopy. J Am Acad Dermatol. 2000;42(1 Pt 1):25-32. ++7. Dalton SR, Gardner TL, Libow LF, Elston DM. Contiguous lesions in lentigo maligna. J Am Acad Dermatol. 2005;52:859-862. [PubMed: 15858478] ++8. Bichakjian CK, Halpern AC, Johnson TM, et al. Guidelines of care for the management of primary cutaneous melanoma. J Am Acad Dermatol. 2011;65(5):1032-1047. [PubMed: 21868127] ++9. Buettiker UV, Yawalkar NY, Braathen LR, Hunger RE. Imiquimod treatment of lentigo maligna: an open-label study of 34 primary lesions in 32 patients. Arch Dermatol. 2008;144(7):943-945. [PubMed: 18645150] ++10. Erickson C, Miller SJ. Treatment options in melanoma in situ: topical and radiation therapy, excision and Mohs surgery. Int J Dermatol. 2010;49(5):482-491. [PubMed: 20534080] ++11. Huang CC. New approaches to surgery of lentigo maligna. Skin Therapy Lett. 2004;9(5):7-11. [PubMed: 15146261] ++12. Mahoney MH, Joseph M, Temple CL. The perimeter technique for lentigo maligna: an alternative to Mohs micrographic surgery. J Surg Oncol. 2005;91(2):120-125. [PubMed: 16028282] ++13. de Moraes AM, Pavarin LB, Herreros F, et al. Cryosurgical treatment of lentigo maligna. J Dtsch Dermatol Ges. 2007;5(6):477-480. ++14. The National Comprehensive Cancer Network. National Clinical Guidelines in Oncology: Melanoma, 2009. http://www.mmmp.org/mmmpFile/image/conv%20ther/NCCN%20guidelines_Melanoma.pdf. Accessed April 20, 2012.