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Cysts with epithelial lining

7  Cysts of the skin and subcutis

7.1  Cysts with epithelial lining

7.1.1  Cysts with lining of epidermal type

7.1.1.1  Epidermal (infundibular) cyst

Clinical signs:

  • probably the most common cyst
  • size usually several milimeters
  • contents: keratin

Etiology:

  • etiology unknown
  • dilatation of hair follicle
  • sometimes on the basis of epithelial inclusions (traumatic)

Pictures

Epidermal cyst, face:
Atheroma, CLINIC (659)

Multiple epidermal cysts and comedones of the back (atheromatosis):
Atheroma, CLINIC (661)

Atheroma, ear lobe:
Atheroma, ear, CLINIC (2814)

Histology:

Cyst with epidermal lining with granular layer, no adnexa, filled with keratin. Does not contain hairs. Sometimes with rupture and inflammation, often granulomatous or purulent.

Pictures

Epidermal cyst:
Epidermal (infundibular) cyst, HE 10x (1955)
Epidermal (infundibular) cyst, HE 40x (1956)

Epidermal cyst: Epidermal cyst, inflammation:
Epidermal cyst, inflammation, HE 20x (211)
Epidermal cyst, inflammation, HE 40x (212)

Epidermal cyst:
Epidermal cyst, HE 40x (12356)

Epidermal cyst:
Cyst, epidermal (infundibular), HE 40x (12660)

Epidermal cyst:
Epidermoid cyst, HE 40x (10818)

Epidermal cyst with foreign body reaction:
Epidermal cyst, ruptured, with foreign body reaction, HE 20x (12357)

Epidermal cyst, regression, giant cells, Russel's bodies:
Epidermal cyst with inflammation and regression, HE 40x (12661)
Epidermal cyst, regressive, inflammed, HE 40x (12985)

Ruptured epidermal/infundibular cyst:
Cyst, epidermal (infundibular), ruptured, HE 20x (5459)

Epidermal (infundibular) cyst with granulomatous reaction to keratin; above the cyst there is palisading granuloma (granuloma annulare):
Epidermal cyst and granuloma annulare, HE 40x (6067)

Atheroma contents:
Atheroma contents, HE 40x (10606)

Epidermal cyst with squamous cell carcinoma:
Squamous cell carcinoma within an infundibular cyst, HE 40x (4836)  [zoomify]

Epidermal cyst with squamous cell carcinoma:
Squamous cell carcinoma, infundibular cyst, HE 20x (13994)

Calcifying epidermal cysts of the vagina:
Calcificating cysts of the vagina, HE 40x (6205)

Tiny follicular cyst with variable lining:
Hybrid epidermal cyst, HE 20x (13711)
Hybrid epidermal cyst, HE 20x (13712)

Tiny epidermal cyst with Darier-like dyskeratosis (accidental finding):
Epidermal cyst, Darier-like changes, HE 60x (13930)

7.1.1.1.3  Epidermal inclusion cyst

Clinical signs:

  • location: areas without hair follicles (esp. palms)
  • association: trauma

Histology:

Pathology is similar to the epidermal (infindibular cyst).

Pictures

Epidermal inclusion cyst, palm:
Epidermal (inclusion) cyst of the palm, HE 20x (2667)

7.1.1.1.4  Hair matrix cyst

Clinical signs:

  • occurs at any age, but especially in children and young adults

Histology:

The wall of this cyst consists of maturing basaloid cells in several layers. The cyst contains amorphous keratinous masses. Small cavities may occur within the wall of the cyst. The pattern of keratinisation resembles that of hair matrix.

7.1.1.1.5  Epidermal proliferating cyst

Introduction:

Rare type of epidermal cyst, where the epithelium proliferates like in proliferating trichilemal cyst. Differentiation of a carcinoma within the epidermal cyst (malignant proliferating epidermal cyst) is difficult (cellular atypia, infiltrative growth).

Prognosis is usually good.

Histology:

Epidermal cyst with granular layer, filled with keratin squames, partially or completely filled by proliferating squamous epithelium with atypia.

Malignant variant has infiltrative growth, celluar atypia and high mitotic activity.

Pictures

Proliferating epidermal cyst:
Proliferating trichilemmal cyst, HE 20x (4954)  [zoomify]

7.1.1.2  Trichilemmal cyst

Clinical signs:

  • location: scalp, face, back, genital
  • round, soft nodules, size up to several centimeters, solitary or multiple
  • clinicians call this cyst (together with epidermal cyst) atheroma
  • contents: yellowish masses, sometimes calcified

Pictures

Trichilemmal cysts and comedones of the nose, actinic elastosis:
Cyst, sebaceous, CLINIC (695)

Histology:

Cyst, often multiple, filled with homogenous, eosinophilic mass. Lining is trichilemmal with gradual keratinisation. Cornified layer nor granular layer are present. Hairs are not present. Sometimes inflammation, dystrophic calcifications, cholesterol crystals and foamy macrophages.

7.1.1.3  Proliferating trichilemmal cyst

Clinical signs:

  • age: elderly, esp. women
  • location: usually scalp
  • subcutaneous nodules, sometimes ulcerating

Histology:

Roundish tumor, sometimes partially cystic, with well defined borders; consisting of lobules of squamous epithelium with irregular, often abrupt keratinisation. Amorphous keratin masses form a substantial part of the tumor. The mode of keratinisation is of trichilemmal type. Squamous eddies and focal calcifications are usually present as well.

7.1.1.4  Dermoid cyst

Clinical signs:

  • location: head, neck
  • inborn lesions
  • size up to 4 cm

Histology:

Cyst with lining of epidermal type. The wall contanins other structures, like hairs with sebaceous glands and sweat glands (eccrine as well as apocrine).

7.1.1.5  Cystic teratoma

Clinical signs:

  • very rare in the skin
  • inborn

Histology:

Cyst containing mixture of various tissues (gastrointestinal or respiratory epithelium, nervous tissue, muscle and other).

7.1.1.6  Cystic teratoma of the ovary

Introduction:

Teratomas of the ovary can take various forms. Common is dermoidal cyst, lined by more or less normal epidermis, including skin adnexa. The cyst contains keratin, sebum and hairs. Sometimes malformed teeth can be found as well.

In more complex form of teratomas (bidermoma, tridermoma) many other tissues can be found (epithelium, neural tissue, cartilage and other).

Histology:

Skin with adnexa, accumulation of the sebum and keratin. Sometimes other tissues can be found as well.

Pictures

Ovary, dermoid cyst:
Dermoid cyst, ovary (mature teratoma), HE 40x (6091)

Dermoidal cyst of the ovary, where the epidermis transforms into conjunctiva-like epithelium:
Teratoma of the ovary, skin, conjunctiva, smooth muscle, HE 40x (6087)

Teratoma of the ovary:
Mature teratoma, HE 40x (6410)

7.1.1.7  Pigmented follicular cyst

Clinical signs:

  • pigmented lesion resembling nevus

Histology:

Infundibular cyst containing keratin and thick pigmented hairs; the wall of the cyst with rete ridges, but without sebaceous glands.

Pictures

Pigmented follicular cyst, ruptured, with granulomatous reaction:
Pigmented follicular cyst, HE 40x (6129)

Another case:
Cyst follicular, pigmented, HE 40x (13233)
Cyst follicular, pigmented, HE 40x (13234)

Pigmented follicular cyst, resoption:
Cyst follicular, pigmented, HE 60x (13441)

Pigmented follicular cyst:
Cyst follicular, pigmented, HE 20x (13847)

7.1.1.8  Steatocystoma multiplex

Clinical signs:

  • autosomal dominant inheritance
  • multiple round nodules, size 1 – 3 cm
  • location: sternal region, axilla, arms
  • steatocystoma simplex: isolated lesion of similar appearance in adults

Histology:

Cyst with thin wall, keratinisation. The wall is usually folded. Keratin layer shows fine undulations and PAS positivity. Granular layer is not present. Sebaceous glands are found within the wall of the cyst. Usually some fine, lanuginous hairs are found as well.

7.1.1.9  Skin keratocyst

Introduction:

This cyst appears within the scope of multiple basal cell nevi. The lining is epidermoid, no granular layer. Contains keratin.

7.1.1.10  Vellus hair cyst

Histology:

Tiny roudnish cyst, contating keratin and lanuginous hairs.

7.1.1.11  Cystis colli mediana, thyreoglossal duct cyst

Clinical signs:

Midline cyst, near hyoid bone.

Histology:

Variable lining: squamous and/or respiratory, thyroid or salivary gland tissue is sometimes nearby.

Pictures

Cystis colli mediana:
Cystis colli mediana, HE 60x (14043)

7.1.1.12  Giant comedo

Histology:

Cyst with thick wall, contaning lamellar keratin; communication with the surface is usually broad, granular layer prominent. Inflammatory changes often present.

7.1.1.13  Milium

Clinical signs:

Small (1 – 2 mm) epidermal cyst. Location is variable (face often). Multiple, sometimes accompanies scarring dermatis, surgeries, burns, abrasions. May be seen in some inborn syndromes (e.g. Bazex).

Histology:

Milium is roundish, tiny epidermal (infundibular) cyst filled with keratin. Sometimes part of a follicle. Similar cysts can arrise in healing of epidermolysis bullosa dystrophica.

7.1.2  Thymic cyst

Clinical signs:

  • location: near the thymus (mediastinum, neck)

Histology:

Thymic tissue (with Hassal's bodies) is found within the wall of the cyst. Lining is variable: epidermoid, cubic, cylindrical or pseudostratified epithelium.

7.1.3  Bronchogenic cyst

Clinical signs:

  • location: sternal region (chin, neck, sternum)
  • the cyst contains fluid
  • inborn lesion

Histology:

Cyst containing fluid, linded with cylindrical or pseudostratified ciliated epithelium. Mucinous glands, smooth muscle and sometimes cartilage are found in the wall or near the cyst. Dense lymphoid infiltrate within the wall of the cyst is not present.

7.1.4  Branchial cleft cyst

Clinical signs:

  • location: lateral, near the sternocleidoid muscle
  • cyst or sinus
  • sometimes skin tags in a neighbourhood

Histology:

Contains fluid, often with cholesterol crystals. Lining is formed by epidermoid epitelium near the surface and ciliated cylindrical epitelium in deeper parts. The wall contains heavy lymphoid infiltrate with follicular centers.

Pictures

Branchiogenic cyst:
Branchiogenic cyst, HE 40x (10646)

7.1.5  Cutaneous ciliated cyst of the lower limbs

Clinical signs:

  • location: lower extremities
  • affects women
  • similar cyst occurs on the back of black people

Histology:

Irregular, sometimes multiple cyst lined by ciliated cylindrical epithelium.

Pictures

Cutaneous ciliated cyst of the lower limbs:
Ciliated cyst, HE 20x (1224)
Ciliated cyst, HE 40x (1225)

7.1.6  Vulval mucinous and ciliated cyst

Clinical signs:

  • location: vulva

Histology:

Cyst with ciliated lining, contains mucin.

7.1.7  Gartner's duct cyst

Clinical signs:

  • location: lateral vaginal walls, rarely vulva
  • size: small
  • benign (from mesonephric duct)

Histology:

Cuboidal cells without mucin.

Pictures

Gartner's duct cyst:
Gartner's cyst, labium minus, HE 20x (5324)

7.1.8  Endometriosis

Clinical signs:

  • location: abdominal; navel, postsurgical scars

Histology:

Endometrial glands and stroma, deposits of hemosiderin.

7.1.9  Median raphe cyst

Clinical signs:

  • location: penis, perineum

Histology:

Cyst lined with columnar pseudostratified epithelium, sometimes mucinous.

Pictures

Median raphe cyst:
Median raphe cyst, HE 20x (1950)
Median raphe cyst, HE 40x (1951)
Median raphe cyst, HE 40x (2269)

Another case, with inflammation and multilayered epithelial lining:
Median raphe cyst, HE 40x (4750)  [zoomify]

Another case, cylindric epithelium, pseudoabscess (woman, perineum):
Cystis mediana perinei, HE 20x (6272)

7.1.10  Hidrocystoma

Clinical signs:

Cystic tumor with epithelial lining corresponding to epithelium of the sweat glands. Contains serous fluid.

7.1.10.1  Eccrine hidrocystoma

Clinical signs:

  • cystic lesion
  • size up to 3 mm
  • location: face

Histology:

Cystic cavity lined by eccrine epithelium with two layers of cuboidal cells.

7.1.10.2  Apocrinne hidrocystoma (and its papillary variant)

Clinical signs:

  • cystic lesion
  • size up to 15 mm
  • location: face, sometimes elwhere (scalp, ears, chest, shoulders)

Histology:

Cystic lesion, sometimes with papillary formations; the cells show apocrine (decapitation) secretion; myoepithelial cells are on the periphery.

7.1.11  Apocrine cystadenoma (papillary)

Clinical signs:

Similar to the apocrine hidrocystoma.

Histology:

Similar to the apocrine hidrocystoma, but focally papillary projections to the lumen are present (true papillae with fibrovascular stroma).

Pictures

Hidrocystoma with papillary proliferation (papillary cystadenoma):
Cystadenoma, apocrine, papillary, HE 60x (13819)


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