Trichoepithelioma is a

neoplasm A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists ...

of the adnexa of the

skin Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation. Other cuticle, animal coverings, such as the arthropod exoskeleton, have diffe ...

. Its appearance is similar to

basal cell carcinoma Basal-cell carcinoma (BCC), also known as basal-cell cancer, is the most common type of skin cancer. It often appears as a painless raised area of skin, which may be shiny with small blood vessels running over it. It may also present as a raise ...

. One form has been mapped to

chromosome 9 Chromosome 9 is one of the 23 pairs of chromosomes in humans. Humans normally have two copies of this chromosome, as they normally do with all chromosomes. Chromosome 9 spans about 138 million base pairs of nucleic acids (the building blocks of D ...

p21.

Types

Trichoepitheliomas may be divided into the following types: :*

Multiple familial trichoepithelioma CYLD cutaneous syndrome (CCS) is the recently designated term for three rare inherited cutaneous adnexal tumor syndromes: multiple familial trichoepithelioma (MFT1) (also termed epithelioma adenoides cysticum and epithelioma adenoides cysticum of ...

Solitary trichoepithelioma A solitary trichoepithelioma is a cutaneous condition characterized by a firm dermal papules or nodules most commonly occurring on the face. See also * Trichoepithelioma * Skin lesion A skin condition, also known as cutaneous condition, is a ...

Desmoplastic trichoepithelioma A desmoplastic trichoepithelioma is a cutaneous condition characterized by a solitary, firm skin lesion on the face. Treatment Desmoplastic trichoepithelioma is a benign tumour and can be managed safely with surgical removal, electrodesiccation ...

Pathology

Trichoepitheliomas consists of nests of basaloid cells, with palisading. They lack the myxoid stroma and artefactual clefting seen in basal cell carcinoma.

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 ...

are uncommon when compared to basal cell carcinoma.

Diagnosis

Trichoepiteliomas often contain

Merkel cell Merkel cells, also known as Merkel-Ranvier cells or tactile epithelial cells, are oval-shaped mechanoreceptors essential for light touch sensation and found in the skin of vertebrates. They are abundant in highly sensitive skin like that of the f ...

s; an immunostain for

CK20 Keratin 20, often abbreviated CK20, is a protein that in humans is encoded by the ''KRT20'' gene. Keratin 20 is a type I cytokeratin. It is a major cellular protein of mature enterocytes and goblet cells and is specifically found in the gastric ...

can be used to demonstrate this.

References

External links

{{Tumors of skin appendages Epidermal nevi, neoplasms, and cysts