Letters to the Editor

Lentigo Maligna Melanoma and Excisional Biopsy Techniques



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Am Fam Physician. 1999 Mar 1;59(5):1108-1114.

to the editor: As physicians who are on the receiving end of consultations from our primary care colleagues, we read with interest Dr. Rose's article, “Recognizing Neoplastic Skin Lesions: A Photo Guide.”1 While the article contains illustrative photographs and much useful information, two issues relating to the diagnosis and treatment of malignant melanoma did not reflect current dermatologic recommendations.

The first issue concerns the discussion of lentigo maligna (Hutchison's melanotic freckle). By including it in the discussion of blue nevi, congenital nevi and dysplastic nevi, which may all be true precursors of melanoma, the article suggests that lentigo maligna is some sort of premalignant lesion whose progress should be followed until “one or more nodules” signal its change to an invasive lesion. Lentigo maligna is considered by most dermatologists to be a melanoma in situ and prompt and complete excision is recommended before it becomes invasive, at which point it is then called lentigo maligna melanoma. Furthermore, Figure 18 is mislabeled as “lentigo maligna,” a preinvasive melanoma, rather than as lentigo maligna melanoma. This may confuse the reader, since the caption calls attention to the “nodules signaling invasiveness.” In our opinion, Figure 18 is not a classic example of either lentigo maligna or lentigo maligna melanoma, which can be difficult to distinguish clinically from a solar lentigo or flat seborrheic keratosis. A high index of suspicion is often necessary to prevent a delayed or missed diagnosis of lentigo maligna.

The second, more important contention is with Dr. Rose's discussion of biopsy techniques. He writes, “If a cosmetically acceptable result would be difficult to obtain . . . punch biopsy of several areas may be performed, including the margins and any raised areas.” Histologically, melanomas are diagnosed more by the overall architecture of the entire lesion than by the cytologic abnormality of individual melanocytes. Even the best dermatopathologists have difficulty diagnosing melanoma in a collection of 2- and 3-mm skin punches.

General pathologists, who service the skin pathology for most family physicians, would have even more difficulty making an accurate diagnosis in this scenario. Furthermore, the ugliest part of a pigmented lesion may not be the most diagnostic. In fact, in the case of a congenital or acquired melanocytic neoplasm that has undergone malignant transformation, the “raised area” may be the only normal area of the lesion. Without adequate sample size, the patient may be subjected to unnecessary mutilating surgery or, even worse, may be falsely reassured into simply observing a potentially lethal melanoma. If the physician is unable to perform an adequate biopsy in his or her office because the lesion is too big, the patient should be referred to someone whose office is better prepared to take care of it.

We do not agree that “multiple punch biopsies of selected areas . . . is an acceptable method for reaching a diagnosis.” An excisional biopsy is critical for the diagnosis of cutaneous melanoma because both the prognostic information and the surgical therapy are based directly and primarily on the depth of the invasion as measured in the biopsy specimen. Dr. Rose fails to mention the well-established relationship between melanoma thickness and mortality. The sampling errors that are inherent with multiple punch biopsies prevent accurate depth determination. This can deny patients the benefit of essential prognostic counseling and impede proper management of the melanoma. Current standards of care for the surgical margins of melanoma excision are based directly on melanoma thickness. If referral for excisional biopsy is not an option, then the largest possible elliptical incisional biopsy, both through the most ominous or nodular area and including the border, is less than ideal, but may be acceptable.

REFERENCE

1. Rose L. Recognizing neoplastic skin lesions: a photo guide. Am Fam Physician. 1998;58:873–84.

in reply: I am pleased that my article has provoked some constructive feedback. In an article that focused on recognition and early diagnosis of skin neoplasia, the section on biopsy and surgery was exceedingly brief.

Squamous cell carcinoma (SCC) is often quite invasive. In its “Guidelines for Care for Cutaneous Squamous Cell Carcinoma,”1 the American Academy of Dermatology (AAD) recommends biopsy before or at the time of definitive therapy. Associated lymph nodes should be sought and biopsied. Recommendations for therapy include the following:

  • Curettage and electrosurgery for small primary lesions on areas of skin exposed to the sun.

  • Cryosurgery for primary lesions, especially when other forms of surgery are refused or contraindicated.

  • Laser surgery.

  • Excision with adequate lateral and deep margins for both primary and recurrent lesions.

  • Mohs' micrographic surgery, especially for recurrent lesions or more aggressive primary lesions.

  • Ionizing irradiation in selected patients for some recurrent cancers and for palliation of inoperable cancers. Irradiation may aggravate verrucous carcinoma.

Treatments that were still being evaluated by the AAD included photodynamic therapy, intralesional injection with interferon, and retinoids, both oral and topical.1

For the treatment of a small basal cell carcinoma that is growing slowly, easily accessible and less than 1 cm in diameter, any of the treatment modalities listed for squamous cell carcinoma may be used. Larger, more aggressive lesions, those that have ulcerated, nodular basal cell carcinoma and infiltrating (morpheaform) lesions should be excised with a safe margin.2

Hutchison's freckle (lentigo maligna) was considered to be a premalignant lesion in the AAD guidelines. Many older patients with this lesion will have it for many years without experiencing an invasive malignant change. Lentigo maligna is now classified as a carcinoma in situ, which should be excised. Some dermatologists prefer to use cryotherapy, chemocautery or dermabrasion.3

When the appearance or behavior of any lesion suggests that it may be a malignant melanoma, there is no role for punch or wedge biopsy. The lesion should be removed with an adequate margin. If excision would require special skills or equipment not available to the primary physician, the patient should be referred. Sometimes, a pigmented lesion that would be difficult to excise completely has a low possibility of malignancy. We hate to excise a benign lesion when excision will create a significant scar or require plastic surgery procedures, but most dermatologists believe that any suspicious lesion should be excised completely. Only a minority of dermatologists will use a variety of biopsy techniques to make the diagnosis.46 It is important that a biopsy or an excision be at least 4 mm deep to allow staging of any malignant changes.

For complete excision of any large malignant skin lesions or those in difficult situations, Mohs' micrographic surgery is recommended.

REFERENCES

1. Guidelines of care for cutaneous squamous cell carcinoma. Committee on Guidelines of Care. Task Force on Cutaneous Squamous Cell Carcinoma. J Am Acad Dermatol. 1993;28:628–31.

2. Drake LA, Ceilley RI, Cornelison RL, Dobes WA, Dorner W, Goltz RW, et al. Guidelines of care for basal cell carcinoma. The American Academy of Dermatology Committee on Guidelines of Care. J Am Acad Dermatol. 1992;26:117–20.

3. Cohen LM. Lentigo maligna and lentigo maligna melanoma. J Am Acad Dermatol. 1995;33:923–36.

4. Slade J, Marghoob AA, Salopek TG, Rigel DS, Kopf AW, Bart RS. Atypical mole syndrome: risk factor for cutaneous malignant melanoma and implications for management. J Am Acad Dermatol. 1995;32:479–94.

5. Salopek TG, Slade J, Marghoob AA, Rigel DS, Kopf AW, Bart RS, et al. Management of cutaneous malignant melanoma by dermatologists of the American Academy of Dermatology. I. Survey of biopsy practices of pigmented lesions suspected as melanoma. J Am Acad Dermatol. 1995;33:441–50.

6. Guidelines of care for malignant melanoma. Committee on Guidelines of Care. Task Force on Malignant Melanoma. J Am Acad Dermatol. 1993;28:638–41.

Send letters to Kenneth W. Lin, MD, MPH, Associate Deputy Editor for AFP Online, e-mail: afplet@aafp.org, or 11400 Tomahawk Creek Pkwy., Leawood, KS 66211-2680.

Please include your complete address, e-mail address, and telephone number. Letters should be fewer than 400 words and limited to six references, one table or figure, and three authors.

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