A blue nevus is a type of coloured mole, typically a single well-defined blue-black bump. The blue colour is caused by the pigment being deep in the skin. Diagnosis is by visualisation and dermoscopy. A biopsy is sometimes performed, or the whole lesion surgically removed. The outcome is generally good but there is a small chance of cancerous transformation. Differential diagnosis includes

dermatofibroma A dermatofibroma, or benign fibrous histiocytomas, is a benign nodule in the skin, typically on the legs, elbows or chest of an adult. It is usually painless. It usually ranges from 0.2cm to 2cm in size but larger examples have been reported. It ...

and melanoma. Blue nevi are more common in females than males. It was first studied in 1906 by Tièche, a student of Josef Jadassohn.

Classification

Blue nevi may be divided into the following types: * A ''patch blue nevus'' (also known as an "acquired dermal melanocytosis", and "dermal melanocyte hamartoma") is a cutaneous condition characterized by a diffusely gray-blue area that may have superimposed darker macules. * A ''blue nevus of Jadassohn–Tièche'' (also known as a "common blue nevus", and "nevus ceruleus") is a cutaneous condition characterized by a steel-blue

papule A papule is a small, well-defined bump in the skin. It may have a rounded, pointed or flat top, and may have a dip. It can appear with a stalk, be thread-like or look warty. It can be soft or firm and its surface may be rough or smooth. Some ha ...

or nodule. * A ''cellular blue nevus'' is a cutaneous condition characterized by large, firm, blue or blue-black nodules. * An ''epithelioid blue nevus'' is a cutaneous condition most commonly seen in patients with the Carney complex. * A ''deep penetrating nevus'' is a type of benign melanocytic skin tumor characterized, as its name suggests, by penetration into the deep dermis and/or subcutis. Smudged chromatic is a typical finding. In some cases mitotic figures or atypical melanocytic cytology are seen, potentially mimicking a malignant melanoma. Evaluation by an expert skin

pathologist Pathology is the study of the causes and effects of disease or injury. The word ''pathology'' also refers to the study of disease in general, incorporating a wide range of biology research fields and medical practices. However, when used in t ...

is advisable in some cases to help differentiate from invasive melanoma. * An ''amelanotic blue nevus'' (also known as a "hypomelanotic blue nevus") is a cutaneous condition characterized by mild

atypia Atypia (from Greek, ''a'' + ''typos'', without type; a condition of being irregular or nonstandard) is a histopathologic term for a structural abnormality in a cell, i.e. it is used to describe atypical cells. Atypia can be caused by an infection ...

and pleomorphism. * A ''malignant blue nevus'' is a cutaneous condition characterized by a sheet-like growth pattern,

mitoses In cell biology, mitosis () is a part of the cell cycle in which replicated chromosomes are separated into two new nuclei. Cell division by mitosis gives rise to genetically identical cells in which the total number of chromosomes is maintai ...

necrosis Necrosis () is a form of cell injury which results in the premature death of cells in living tissue by autolysis. Necrosis is caused by factors external to the cell or tissue, such as infection, or trauma which result in the unregulated dig ...

, and cellular

. blue nevus - intermed mag.jpg,

Micrograph A micrograph or photomicrograph is a photograph or digital image taken through a microscope or similar device to show a magnify, magnified image of an object. This is opposed to a macrograph or photomacrograph, an image which is also taken ...

of a blue nevus showing the characteristic pigmented

melanocyte Melanocytes are melanin-producing neural crest-derived cells located in the bottom layer (the stratum basale) of the skin's epidermis, the middle layer of the eye (the uvea), the inner ear, vaginal epithelium, meninges, bones, and hear ...

s between bundles of collagen.

H&E stain Hematoxylin and eosin stain ( or haematoxylin and eosin stain or hematoxylin-eosin stain; often abbreviated as H&E stain or HE stain) is one of the principal tissue stains used in histology. It is the most widely used stain in medical diagnos ...

SkinTumors-408.jpg, Blue nevus SkinTumors-415.jpg, Cellular blue nevus SkinTumors-456.jpg, Epithelioid blue nevus Skin Tumors-P6231211.jpg, Malignant blue nevus

References

External links

{{Skin tumors, nevi and melanomas Melanocytic nevi and neoplasms

Classification

See also

References

External links