1 Lentigo Maligna

Lentigo maligna occurs in photo-exposed areas. Atypical melanocytes proliferate along the basement membrane without crossing it: lentigo maligna is a melanoma in situ. When melanocytes cross the basement membrane and invade the dermis the tumor is called lentigo maligna melanoma.

Clinically, lentigo maligna (Fig. 9.1) presents as a nonhomogeneous pigmented macule on sun-exposed skin, with irregular contours.

Fig. 9.1
figure 1

Clinical aspect of actinic lentigo

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The IVCM features are as follows (Fig. 9.2a–d):

  • Relatively well-preserved epidermis with regular honeycomb pattern (not shown here)

  • Atypical roundish and/or dendritic cells (that correspond to large cells of different shapes and sizes) at the dermo-epidermal junction (orange stars) and the suprabasal layers of the epidermis (pagetoid cells; blue arrows)

Fig. 9.2
figure 2

IVCM features of actinic lentigo (a–d)

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On optical microscopy the histologic features are as follows (Fig. 9.3e–i):

  • At low magnification (e, f), melanocytic proliferation (red dotted line) occurs along the basement membrane, without crossing it.

  • Melanocytes are marked in red in immunohistochemistry by the anti-Melan-A antibody (g).

  • At high magnification (h, i), atypical melanocytes proliferate along the basement membrane in a lentiginous mode (black circle). Some nests at the level of the basement membrane are visible (blue arrows).

Fig. 9.3
figure 3

Histological features of actinic lentigo (e–i). (e, f) ×100 HES. (g) ×100 Anti-Melan-A Ab. (h, i) ×200 HES

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2 Melanoma

Eyelid melanomas represent less than 1% of palpebral malignant tumors. In melanoma, atypical melanocytes are present in the epidermis and dermis. The most frequent histological types of palpebral melanomas are:

  • Superficial spreading melanoma (SMM)

  • Lentigo malignant melanoma (LMM)

The clinical aspect (Fig. 9.4) of this eyelid melanoma is a heterogeneous and irregular dark brown pigmentation.

Fig. 9.4
figure 4

Clinical aspect of eyelid melanoma

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The IVCM features are as follows (Fig. 9.5a–e):

  • Disarranged epithelium (a–c) with large hyperreflective dendritric (red circle) and roundish pagetoid cells (yellow arrows and image c)

  • Large hyperreflective polymorphic cells (orange stars) in the superficial dermis (d, e) in case of invasive melanoma

Fig. 9.5
figure 5

IVCM features of eyelid melanoma (a–e)

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On optical microscopy the histologic features are as follows (Fig. 9.6f–k):

  • At low magnification (f–i), melanocytic proliferation invades the dermis (black circle), and its intraepidermal lateral component looks lentiginous (blue dotted lines). Melanocytes are stained in red by anti-Melan-A antibody.

  • At high magnification (j, k), the dermal component is composed of melanocytes arranged in nests (green diamonds). The intraepidermal lateral component is lentiginous (blue dotted line). Some mitoses are visible (black arrows).

Fig. 9.6
figure 6

Histological features of eyelid melanoma (f–k). (f, g) ×50 HES. (h, i) ×50 Anti-Melan-A Ab. (j, k) ×200 HES

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