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Stage 0 TisN0M0 Melanoma in situ lentigo maligna

last modified on: Wed, 01/31/2018 - 13:37

Stage 0 TisN0M0 Melanoma in situ,  lentigo maligna

return to: Melanoma (Evaluation and Management)

Definition: Histopathologic diagnosis based on criteria of melanoma cells being confined to the epidermis above the basement membrane. Histopathologic analysis shows basilar melanocytic atypia, hyperplasia, and spread along the basement membrane or throughout the epidermis (pagetoid spread). Clinically, the lesions are often macules (flat within the level of the skin) with irregular borders and variation of color, though the clinic presentation is variable. Subtypes of MIS (melanoma in situ) include lentigo maligna and superficial spreading. Lentigo maligna presents as a flat macule with geographic shape with coloration from tan to brown to black. Superficial spreading melanoma presents as a slow growing plaque (elevated, flat lesion) with pigment variation mixture of broown, black, blue, red, and gray regions.

Recommended margins: Standard excision with 5 mm margins results in postive margins up to 33% of cases (2013 Kunishige et al). For this reason, MIS is often excised in a staged procedure, taking 5 mm (or greater) margins and doing final reconstruction after final pathology has been reviewed. If the final pathology shows areas of invasion in the specimen or involved peripheral margins, additional margins can then be taken as needed for appropriate stage.

Our practice at the University of Iowa is to most commonly resect melanoma in situ employing Mohs surgery. For those cases with an invasive component warranting sentinel node biopsy (greater than a T1a melanoma -- not melanoma in situ) we will endeavor to obtain clear margins with 5-9 mm periphery of normal tissue about the resection and save the Mohs resection for peripheral clearance after the resection so as to not interfere with lymphatic drainage prior to sentinel node biopsy. For those cases that are not in need of a sentinel node biopsy (such as T1a melanoma surrounded by melanoma in situ, known metastases, or other reasons for not performing a sentinel node biopsy) we will commonly perform a 'moat procedure' (see:Case Example Lip Reconstruction Peri-alar Crescentic Advancement Flap  and Case Example Split Thickness Skin Graft STSG Zimmer Dermatome settings).  The moat procedure' involves Mohs surgery to clear periphery (often closing the 'moat' defect around the tumor) for subsequent resection of the central portion with confidence that the reconstruction can be done with clear margins.

References

  1. Hazan C, et al. Staged excision for lentigo maligna and lentigo maligna melanoma: A retrospective analysis of 117 cases. Journal of American Academy of Dermatology. 2008. 142-148.
  2. Moller MG, et al. Surgical Management of Melanoma-In-Situ Using a Staged Marginal and Central Technique. Annals of Surgical Oncology. 2009. 16:1526-1536.
  3. Wolff K, Johnson RA. Melanoma precursers and primary cutaneous melanoma. Fitzpatrick's Color Atlas and Synposis of Clinical Dermatology, 6th edition. 2009.
  4. Kunishige JH, Brodland DG, and Zitelli JA: Margins for standard excision of melanoma in situ, J Am Acad Dermatol 2013 Jul;69(1):164