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Unformatted text preview: long-term mild exposure, though the exact mechanism
behind the pathogenesis remains unknown.
Screening and Diagnosis
In one study, multivariate analysis identiﬁed the following six risk
factors as important in the development of malignant melanoma27:
1. A family history of melanoma;
2. A history of three or more blistering sunburns before the age of
3. Blonde or red hair;
4. The presence of actinic keratosis; 5. A history of 3 or more years of an outdoor summer job as a
6. Marked freckling on the upper part of the back.
For a person with one or two of these factors, the risk of melanoma
is increased 3.5-fold; for a person with three or more, the risk is increased 20-fold.
The recommended frequency for melanoma screening should be
based on these six risk factors. Routine screening of low-risk patients
through total body skin examinations performed by healthcare
providers is not a supported practice. Self-screening, however, is
clearly recommended, and excellent educational materials on this
subject are available from the American Academy of Dermatology
and the American Cancer Society. Nevertheless, physicians should
take every opportunity to screen patients as the occasion arises; in
general, the lesions found by physicians are signiﬁcantly thinner than
those detected by patients or their spouses.28
For effective treatment of melanomas, early recognition is critical.
The ABCD (Asymmetry, Border irregularity, Color variegation, Diameter) guidelines for pigmented lesions are frequently used as aids
to melanoma identiﬁcation [see Table 1].29 Melanomas often occur
on sun-exposed areas of the upper trunk and the extremities, and
they are typically asymmetric, with irregular borders and variegated
pigmentation [see Figure 3a]. Occasionally, they lack pigmentation or
are associated with signiﬁcant gross ulceration. Any lesion that appears suspicious for melanoma should undergo biopsy. Histologically, melanomas are characterized by atypical melanocytes with mitotic ﬁgures. Special staining, most commonly with HMB-45 or S100,
may also be performed.
Melanoma may be classiﬁed into histologic subtypes on the basis
of growth pattern and anatomic location. It should be kept in mind, b a Figure 3 Shown are (a) a typical melanoma and (b) an acral lentiginous melanoma. © 2006 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice 3 BREAST, SKIN, AND SOFT TISSUE 4 Malignant Skin Lesions — 5 Table 2—Clark System for Staging Melanoma
Level I Degree of Tumor Invasion 5-Year Survival (%) Malignant melanocytes are confined to
epidermis 99 Level II Malignant melanocytes infiltrate papillary
dermis singly or in small nests 95 Level III Malignant melanocytes fill and expand papillary dermis, with extension of tumor to
papillary-reticular dermal interface (usually
signifying vertical growth phase) 82 Level IV Malignant melanocytes infiltrate reticular
dermis in significant fashion 71 Level V Malignant melanocytes infiltrate subcutaneous fat 49 however, that the spe...
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This note was uploaded on 03/21/2011 for the course ONC 01 taught by Professor Dzodic during the Spring '11 term at Multimedia University, Cyberjaya.
- Spring '11
- The Land