lentigo maligna melanoma

Introduction

Least common of 3 principal melanomas of Caucasians.

Etiology

• lentigo maligna melanoma evolves very slowly from lentigo maligna over a period of years (may take 20 years)
• risk factors:
  • age
  • sun exposure (outdoor occupations, etc)
  • HCTZ (RR=1.2)

Epidemiology

• median age is 65-70
• equal incidence in males & females
• rare in Asians, East Indians, blacks
• 5-10% of primary cutaneous melanomas

Clinical manifestations

• pigmented macules with variation in hues of brown & black plus gray areas indicating focal regression
• areas of blue, black or pink papules & nodules
• non pigmented lesions are rare
• 3 mm to 2 cm or larger in size
• distribution:
  • single isolated lesion on sun-exposed surface
  • especially malar region of cheek & temple
• shape: irregular but sharply defined borders with inlets & peninsulas
• other manifestations of sun-damaged skin
  • telangiectasia
  • marked freckling
  • atrophy & solar keratosis
  • basal cell carcinoma

Differential diagnosis

• lentigo maligna
• seborrheic keratosis
• nodular melanoma; berry-like lesions that can arise from pre-existing nevi

Management

• check for regional lymphadenopathy
• surgical excision
  • margin of at least 1.0 cm beyond clinically visible lesion
  • use of Wood's lamp may help define borders
  • excision down to or including the fascia
  • skin graft will be necessary
  • dissection of regional lymph node only if clinically palpable
  • neoadjuvant topical imiquimod, 5%, cream prior to conservatively staged excision (see lentigo maligna)

More general terms

• cutaneous melanoma

Additional terms

• lentigo maligna
• seborrheic keratosis