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blue nevus

Thursday 23 September 2004

Definition: Blue nevus is gray blue, and usually involves the scalp, sacrum or foot. It is a deep dermal lesion with abundant pigmentation.

Images

- Amelanotic blue naevus mimics dermatofibroma (DF). Usually focal pigment on close inspection. Melan A.

- Agminated blue nevi

Digital cases

- HPC:130
- pathxchange #2206
- UI:336 - Cellular Blue Nevus.
- JRC:10760 : Blue nevus.
- JRC:10784 : Blue nevus.
- JRC:10785 : Blue nevus.

Synopsis

- common blue nevus

  • vaguely nodular collection of poorly melanized spindled melanocytes
  • deeply pigmented dendritic melanocytes within thickened collagen bundles
  • scattered melanophages
  • no mitoses

- cellular blue nevus

  • well-demarcated nodule
  • fascicles and nests of tightly packed
  • moderately sized, spindled to oval melanocytes with scattered melanophages
  • centered in the reticular dermis
  • blunt-ended, bulbus extensions that extend into the subcutaneous fat
  • occasional mitoses
  • significant cytologic atypia
  • areas of necrosis absent

- epithelioid blue nevus (+/- with Carney complex)
- atypical blue nevus
- deep penetrating blue nevus
- sclerosing blue nevus
- amelanotic blue nevus
- malignant blue nevus: malignant melanoma arising in association with a cellular blue nevus or growing in a histologic pattern similar to that of a cellular blue nevus

  • pronounced cytologic atypia
  • hyperchromasia
  • necrosis
  • increased mitotic rate
  • infiltrative growth pattern

Types

- classic blue nevus
- cellular blue nevus
- malignant blue nevus

Variants

- epithelioid blue nevus
- multiple blue nevi
- plaque-type blue nevus (16205067)
- amelanotic blue nevus

Localization

- skin
- Rarely: vagina, spermatic cord, uterine cervix, lymph node, prostate, oral mucosa, bronchus

Epidemiology

- most frequently noted in Asian populations (3-5% in adults)
- 1-2% of white adults
- rarely found in blacks
- uncommon at birth or in the first few years of life, with an estimated prevalence of less than 1 case per 1000 population.

See also

- melanocytic lesions

  • melanoyctic tumors