Atypical (dysplastic) naevus

Atypical (dysplastic) naevus

To be ‘atypical naevi’, lesions must have three of the following in situ characteristics: variegated pigmentation; ill-defined borders; undulating irregular surfaces; or size >5 /uni00A0 mm. Terminology is confused because, although the terms ‘dysplastic’ and ‘atypical’ are often used interchangeably , dysplasia is a histological diag nosis with findings of irregular proliferations of melanocytes at the basal layer of the epidermis. In fact, a small proportion of clinically ‘atypical naevi’ are actually dysplastic when exam . ined microscopically Atypical naevi can be sporadic or familial (familial atypical multiple mole–melanoma [FAMMM] syndrome). Possession of more than five lesions confers a relative risk of melanoma six times greater than usual; within FAMMM syndrome confer a 100% risk of malignant melanoma and patients with FAMMM syndrome should be screened for melanoma 6-monthly , lifelong ( Figure 45.29 ). Data from the World Health Organization suggest that both non-melanoma and melanoma skin cancers continue to increase in incidence, despite educational programmes and wide-ranging changes in uptake of sun protective measures and improvements in sunscreens. Skin cancer is the common - est malignancy in white-skinned people, constituting 33% of all recorded malignancies annually , with 2–3 million new non-melanoma skin cancers and 132 /uni00A0 000 new malignant mela - e melanomas) diagnosed nomas (4.5% of all new cancers ar each year.

Figure 45.28 Giant congenital pigmented naevus (courtesy of St John’s Institute for Dermatology, London, UK). Figure 45.29 Dysplastic naevus (courtesy of St John’s Institute for Dermatology, London, UK).

Atypical (dysplastic) naevus

To be ‘atypical naevi’, lesions must have three of the following in situ characteristics: variegated pigmentation; ill-defined borders; undulating irregular surfaces; or size >5 /uni00A0 mm. Terminology is confused because, although the terms ‘dysplastic’ and ‘atypical’ are often used interchangeably , dysplasia is a histological diag nosis with findings of irregular proliferations of melanocytes at the basal layer of the epidermis. In fact, a small proportion of clinically ‘atypical naevi’ are actually dysplastic when exam . ined microscopically Atypical naevi can be sporadic or familial (familial atypical multiple mole–melanoma [FAMMM] syndrome). Possession of more than five lesions confers a relative risk of melanoma six times greater than usual; within FAMMM syndrome confer a 100% risk of malignant melanoma and patients with FAMMM syndrome should be screened for melanoma 6-monthly , lifelong ( Figure 45.29 ). Data from the World Health Organization suggest that both non-melanoma and melanoma skin cancers continue to increase in incidence, despite educational programmes and wide-ranging changes in uptake of sun protective measures and improvements in sunscreens. Skin cancer is the common - est malignancy in white-skinned people, constituting 33% of all recorded malignancies annually , with 2–3 million new non-melanoma skin cancers and 132 /uni00A0 000 new malignant mela - e melanomas) diagnosed nomas (4.5% of all new cancers ar each year.

Figure 45.28 Giant congenital pigmented naevus (courtesy of St John’s Institute for Dermatology, London, UK). Figure 45.29 Dysplastic naevus (courtesy of St John’s Institute for Dermatology, London, UK).

Atypical (dysplastic) naevus

To be ‘atypical naevi’, lesions must have three of the following in situ characteristics: variegated pigmentation; ill-defined borders; undulating irregular surfaces; or size >5 /uni00A0 mm. Terminology is confused because, although the terms ‘dysplastic’ and ‘atypical’ are often used interchangeably , dysplasia is a histological diag nosis with findings of irregular proliferations of melanocytes at the basal layer of the epidermis. In fact, a small proportion of clinically ‘atypical naevi’ are actually dysplastic when exam . ined microscopically Atypical naevi can be sporadic or familial (familial atypical multiple mole–melanoma [FAMMM] syndrome). Possession of more than five lesions confers a relative risk of melanoma six times greater than usual; within FAMMM syndrome confer a 100% risk of malignant melanoma and patients with FAMMM syndrome should be screened for melanoma 6-monthly , lifelong ( Figure 45.29 ). Data from the World Health Organization suggest that both non-melanoma and melanoma skin cancers continue to increase in incidence, despite educational programmes and wide-ranging changes in uptake of sun protective measures and improvements in sunscreens. Skin cancer is the common - est malignancy in white-skinned people, constituting 33% of all recorded malignancies annually , with 2–3 million new non-melanoma skin cancers and 132 /uni00A0 000 new malignant mela - e melanomas) diagnosed nomas (4.5% of all new cancers ar each year.

Figure 45.28 Giant congenital pigmented naevus (courtesy of St John’s Institute for Dermatology, London, UK). Figure 45.29 Dysplastic naevus (courtesy of St John’s Institute for Dermatology, London, UK).