Cysts with a lining of stratified squamous epithelium: Epidermoid cyst
Milium
Trichilemmal cyst
Vellus hair cyst
Steatocystoma
Dermoid cyst
Cysts lined with non-stratified squamous epithelium: Hidrocystoma, Eccrine or Apocrine
Cysts without an epithelial lining: Mucocele
Digital mucous cyst
Ganglion
3. A cyst is a circumscribed dermal or subcutaneous papule
or nodule that contains fluid or semi-fluid material, so a
cyst is fluctuant.
Cysts can be classified by anatomic location (as they may
occur in virtually any organ of the body), by embryologic
derivation, or by histologic features (of the cyst lining).
True cysts have an epithelial lining that may be composed
of stratified squamous epithelium or other forms of
epithelia. Some “cysts” have no epithelial lining at all
(pseudocysts).
5. CLASSIFICATION OF CYSTS ACCORDING TO
LINING:
I. Cysts with a lining of stratified squamous
epithelium
II. Cysts lined with non-stratified squamous
epithelium
III. Cysts without an epithelial lining
10. SYNONYMS:
1. Epidermoid inclusion cyst
2. Epidermal cyst
3. Epidermal inclusion cyst
4. Infundibular cyst
It is the most common
cutaneous cyst.
Tiny superficial epidermoid
cysts are known as milia.
11. It is derived from the follicular
infundibulum.
They may be primary, or they may
arise from disrupted follicular
structures or traumatically
implanted epithelium (hence the
synonym epidermal “inclusion”
cyst).
18. These lesions are firm to fluctuant well-demarcated, skin-
colored to yellowish mobile dermal nodules, and they
may have a clinically visible punctum representing the
follicle from which the cyst is derived range from a few
millimeters to several centimeters in diameter.
These cysts may be flat or flush to the surface of the skin or
elevated well above the surface. In either case, they are
easily palpable.
It can occur anywhere on the skin, but are most common
on the face, scalp, postauricular, neck, scrotum and
upper trunk.
Non-inflamed epidermoid cysts are usually asymptomatic,
but, with pressure, cyst contents may be expressed that
may have an foul odor.
20. Epidermal cyst in the epigastric region of > 10 years duration
the skin overlying the cyst has been atrophied with some dilated vessels due
to the pressure effect produced by the cyst. The punctum in the central part
of the cyst is so evident.
21. Unlike pilar cysts, the epidermal cyst
wall is fairly delicate and thus prone to
rupture.
Rupture of the cyst wall can result in
an intensely painful inflammatory
reaction, and this is a common reason
for presentation to a physician.
Rupture is followed by foreign body
reaction to keratin extruded into the
dermis and acute inflammation.
22. Inflamed Epidermoid Cyst
Such painful inflammatory reactions to cyst rupture are a frequent cause for
presentation to a physician
23. Development of a BCC or SCC within an epidermoid
cyst is a very rare event.
Multiple epidermoid cysts may occur in the following
settings:
1. Individuals with a history of significant acne vulgaris.
2. Multiple scrotal cysts may lead to scrotal calcinosis via dystrophic
calcification.
3. Gardner syndrome (familial adenomatous polyposis).
4. Nevoid BCC syndrome.
27. Cystic cavity filled with lamellated keratin
lined by a flattened stratified squamous
epithelium including a granular layer.
A surrounding inflammatory response with
both acute and chronic granulomatous
inflammation may be seen as evidence of
prior rupture and resolves with scarring.
In individuals with Gardner syndrome, some
cysts show, as a characteristic feature,
columns of pilomatricoma-like shadow cells
projecting into the cyst cavity.
30. Histopathology of Epidermoid Cyst
showing the cyst wall lined by stratified squamous epithelium with a granular cell layer
(arrow). The central portion of the cyst is filled with keratinaceous debris (star).
31. Histopathology of Epidermoid Cyst of the scrotum
epidermal cyst wall with thin layer of benign stratified squamous epithelium (small
solid arrows) and keratinous debris present in cyst (open arrows). Scrotal skin with
basal pigmentation (large solid arrows) is also noted.
32. Assurance:
Small cysts (e.g. less than 5 mm) don't usually need treatment.
Surgical excision:
Removal may be accomplished by simple excision, or incision and expression of
the cyst contents and wall through the defect. Other techniques of removal include
punch biopsy aspiration followed by curettage and avulsion of the cyst wall.
If the entire cyst wall is not removed, the cyst may recur.
Cysts are more difficult to remove once they have ruptured.
Inflamed epidermoid cysts: It is best to avoid surgery while the cyst is actively
inflamed due to higher risk of infection, wound dehiscence and cyst recurrence. Following
the resolution of the infection, the lesion is excised.
1. Incision and drainage.
2. Antibiotic therapy, occasionally.
3. Intralesional triamcinolone may be helpful in speeding the resolution of the
inflammation.
37. They are small epidermoid cysts containing
keratin usually multiple and are quite
common, occurring in individuals of all ages
and both sexes.
These harmless cysts present as tiny pearly-
white papules.
Between 40% and 50% of infants will have
milia usually resolve during the 1st four
weeks of life while in adults tend to be
persistent.
38. Present as 1–2 mm pearly-white to yellow
fixed subepidermal papules.
Present most commonly on the face usually on
the cheeks, eyelids and forehead.
39. CLINICAL TYPES OF MILIA
1. Primary
Milia
2. Secondary
Milia
3. Milia En
Plaque
4. Neonatal
Milia
5. Juvenile
Milia
6. Multiple
Eruptive Milia
- Found on the
face especially
around eyelids,
cheeks, forehead
and genitalia
- May clear in a
few weeks or
persist for
months or
longer.
- Following
blistering
processes or
superficial
ulceration from
trauma, burn or
cosmetic
procedures.
- May also occur
in areas of
topical drugs e.g.
corticosteroid,
hydroquinone.
- Multiple milia
within an
erythematous
edematous
plaque especially
in middle-aged
women.
- Most often
occurs in the
postauricular
area, but may
also occur eyelid,
cheeks or jaw.
- Affect 40-50%
of newborns.
- Few to multiple.
- Often seen on
the nose, but
may also arise
inside the mouth
on gum margins
(Epstein pearls)
or palate (Bohn
nodules).
- Usually resolve
within1st four wk.
- Persistent
widespread milia
may be
congenital or
appear later in
life.
- Associated with
Rombo, basal
cell naevus,
Gardner, Bazex
syndromes and
other genetic
disorders.
- Crops of
numerous milia
appear over a
few weeks to
months.
- Lesions may be
asymptomatic or
itchy.
- Most often
affect face,
upper arms and
upper trunk.
49. They often clear up spontaneously within a few months.
Elective removal for cosmesis.
Medical:
Topical retinoid: For multiple facial milia, may be helpful in reducing
the number of milia and aiding in the ease of removal.
Minocycline: may improve milia en plaque.
Surgical:
Milia may be de-roofed by incising the epidermis over the milium with a
needle, scalpel or lancet and expressing the milium (may be aided by
the use of a comedo extractor).
They may be destroyed using and curettage, cryotherapy, laser
ablation or electrodesiccation.
50. Nick the surface with an 11 blade or an
18 gauge needle, then gently express
the entire cyst, lining and contents.
Dress with a dab of petrolatum.
53. Pilar Cysts are usually clinically
indistinguishable from epidermoid
cysts, but they are fourfold to fivefold
less common.
They may be inherited as an autosomal
dominant trait.
More frequent in middle-aged females.
90% of trichilemmal cysts are located
on the scalp.
They may be solitary, but frequently
they are multiple.
54. May look similar to epidermoid cysts
present as one or more firm, mobile,
subcutaneous nodules measuring
0.5 to 5 cm in diameter. There is no
central punctum, unlike an
epidermoid cyst.
56. EPIDERMOID CYST PILAR CYST
Most common site Face, neck, trunk
Scalp (90% of pilar
cysts), scrotum
Central punctum Present Absent
Origin
Epithelium or hair follicle
infundibulum
Outer root sheath
Cyst wall
Delicate and prone to
rupture
Thick and less prone to
rupture
Histology Granular layer present Granular layer absent
Excision More difficult
They deliver themselves
through an incision
easily without rupture
57. Cyst walls lined by stratified squamous epithelial
cells that show keratinization that has a palisaded
outer layer, analogous to that of the outer root
sheath of the hair follicle at the isthmus and the sac
surrounding catagen and telogen hairs become
swollen and pale close to the cystic cavity and show
abrupt keratinization without an intervening granular
layer.
The cyst contents consist of homogeneous very
brightly eosinophilic keratinaceous debris that
commonly shows foci of calcification in25% of cases.
A foreign body giant cell response may surround the
cyst if prior wall rupture has occurred.
61. Elective excision before rupture prevents
scarring.
Surgical treatment involves either of
the following methods:
1. Enucleation of the cyst. Typically, they “deliver”
themselves through an incision without
rupture more easily than do epidermoid cysts,
and, therefore, the distinction between a
trichilemmal cyst and an epidermoid cyst can often
be correctly made at the time of excision.
2. Incision followed by expression of contents
and removal of cyst wall – this is often best
achieved with a surgical punch with the cyst
expressed through the hole.
62.
63. Quite rare asymptomatic small, dome-
shaped papules.
They may be inherited in an autosomal
dominant pattern when they occur in early
childhood. Sporadic forms tend to develop
later in teenage years.
Occasionally, solitary cysts are seen. Multiple
lesions are known as “ERUPTIVE” VELLUS
HAIR CYSTS (may be seen in conjunction with
steatocystoma multiplex or pachyonychia
congenita).
67. They are asymptomatic except for
cosmetic concerns.
Most commonly present as
numerous, small, dome-shaped
papules, ranging from skin-
colored to darkly pigmented. They
may be dimpled or umbilicated.
Most commonly located on the
trunk especially the anterior chest.
Most lesions persist indefinitely.
68. The diagnosis of eruptive vellus hair
cysts is often made clinically, because
of typical age of onset, the site of the
lesions, and their appearance.
Incision or puncture of the cyst and
examination of the contents under a
microscope will reveal the vellus
hairs.
Skin biopsy may confirm the
diagnosis.
69. Small cystic structure lined by
stratified squamous
epithelium with epidermoid
keratinization. The cysts
contain loose laminated keratin
and numerous vellus hairs.
A follicle may be found entering
the lower portion of the cyst.
70. Histopathology of Vellus Hair Cyst
Within the dermis there is a cyst lined by squamous epithelium with a granular layer
and containing laminated keratin and numerous vellus hairs.
71. Medical:
Topical retinoic, salicylic acid or lactic acid (long term).
Surgical:
1. Incision and drainage.
2. Needle evacuation.
3. Puncture followed by forceps assisted extraction.
4. Cryotherapy.
5. Laser.
72.
73. Steatocystomas occur as:
I. Single (STEATOCYSTOMA SIMPLEX) or;
II. Multiple(STEATOCYSTOMAMULTIPLEX).
Steatocystoma multiplex is rare and can be
inherited as an autosomal dominant
condition, and is due to mutations in the
KRT17 gene. It may occur in association
with eruptive vellus hair cysts and
pachyonychia congenita.
It is due to hamartomatous malformations
of the pilosebaceous duct junction.
77. They tend to be small (2-20 mm) but they may
be several centimetres in diameter and
appear as soft to firm semi-translucent
cysts in the dermis that drain oily fluid if
punctured.
They are most numerous on the chest and in
the axillae, abdomen, upper arms and groin.
There are unusual facial and acral variants as
well as a rare congenital linear form.
Steatocystomas develop at puberty
presumably due to hormonal stimulus of the
pilosebaceous unit and persist indefinitely.
They are usually asymptomatic except for
cosmetic concerns.
78. Dermal cyst lined by a thin
stratified squamous epithelium,
without a granular layer and
surmounted by a characteristic
thin, irregular, corrugated
eosinophilic lining (cuticle).
Small sebaceous lobules are
found in or immediately adjacent
to the cyst wall.
79. Histopathology of Steatocystoma
The cyst wall is characterized by an undulated, thin stratified epithelium lacking a
stratum granulosum and lined by an eosinophilic cuticle. A search may be required to
identify small sebaceous lobules in or immediately adjacent to the cyst wall (insert)
80. Medical:
Oral isotretinoin is not curative but may temporarily
shrink the cysts and reduce inflammation.
Oral antibiotics; to reduce the inflammation if
present.
Surgical:
1. Excision; If it is tethered to the underlying skin.
2. Incision with removal of the cyst wall; In most
cases, small incisions allow the cyst and its
contents to be extracted through the opening.
3. Cryotherapy.
4. Electrosurgery.
5. Laser.
81.
82. Cutaneous dermoid cyst typically present in an
infant along an embryonic fusion plane as a
discrete, subcutaneous nodule.
It results from sequestration of ectodermal tissue
along embryonic fusion planes during development.
Although dermoid cysts are congenital defects and
may be recognized at birth, these lesions often
escape notice until they become enlarged,infected
or inflamed. This typically occurs by early childhood.
Dermoid cysts in other parts of the body, such as
within the skull, spine or abdominal cavity
particularly the ovaries, may present at any time in
people of all ages.
86. Medial Dermoid Cyst
Note the fullness below the head of the right brow. This lesion must be imaged to
confirm the diagnosis and to distinguish it from an encephalocoele or mucocele.
87. Dermoid Cyst
A subcutaneous mass at the lateral aspect of the right upper eyelid, under the tail of
the brow. Note that the overlying skin is not erythematous, edematous or discolored.
88. Present as firm, non-compressible, non-pulsatile subcutaneous
nodules that often reach a size of 1–4 cm in diameter.
The lesions usually do not transilluminate.
They are most commonly located around the eyes, particularly the
lateral eyebrow but may also occur anywhere in the body e.g.
nose, scalp (often over the anterior fontanelle or the midline
occiput), neck, sternum, sacrum and scrotum.
They can be associated with a nearby pit and/or sinus tract to
underlying tissues.
Dermoid cysts on the nose or midline scalp have a much higher
likelihood of intracranial extension than those in a periocular
location.
89. Lined by keratinizing stratified
squamous epithelium including a
granular layer.
They contain other normal mature
adnexal cutaneous structures such as
hair, sebaceous lobules, eccrine
glands, apocrine glands, or smooth
muscle.
90. Histopathology of Dermoid Cyst
The cyst wall demonstrates a hair follicle (arrow), one of the adnexal structures
that are commonly found in walls of dermoid cysts. Note the kertinized stratified
squamous epithelium lining the cyst.
91. Surgical Excision.
However, as there may be sinus tract or neural
heterotopias, imaging studies may be appropriate prior
to excision, to exclude a connection to the CNS.
92. Surgical Excision of Dermoid Cyst
Before removal, one week and 1.5 years after removal.
93.
94.
95. Hidrocystomas can traditionally divided by histologic
features into;
I. APOCRINE HIDROCYSTOMAS
II. ECCRINE HIDROCYSTOMAS
Also can divided according to number into;
I. SOLITARY (SMITH TYPE)
II. MULTIPLE (ROBINSON TYPE)
May be due to occlusion or blockage of the sweat duct
apparatus, which results in the retention of sweat and a
dilated cystic structure.
96. Apocrine hidrocystomas are relatively common
benign cystic proliferations of the apocrine glands.
In general, eccrine hidrocystomas are thought to
develop from cystic dilation of eccrine ducts due to
retention of eccrine secretions while apocrine
hidrocystomas are thought to represent adenomas of
apocrine secretory sweat gland coils.
99. Asymptomatic. No seasonal variation.
Appear during adulthood, grow slowly, and
usually persist indefinitely.
Typically present as skin-colored to bluish and
shiny cysts.
They are usually solitary soft, dome-shaped,
translucent papules or nodules and most
frequently are located on the eyelids, especially
the inner canthus also head, neck, and trunk.
Consistency is fluctuant and cystic. Size varies
from a few millimeters to approximately 1.5 cm.
Walls, although translucent, are sufficiently
thick & tense that they seldom rupture
spontaneously.
102. Typically present as translucent, clear,
skin-colored cysts on the face although
they may occur in other sites.
May be solitary or multiple and are
occasionally quite numerous and usually
smaller in size and less bluish than
apocrine hidrocystoma.
They are associated with seasonal
variations can enlarge with heat
exposure or during the summer and
regress with exposure to cold and winter.
They are more frequent in females than
in males.
105. They are unilocular to multilocular dermal
cysts lined by one to several layers of
apocrine-type secretory epithelium
cuboidal-to columnar that show bulbous
protrusions (“snouting”) or papillary
projections extend from the secretory layer
into the cyst cavity representing luminal
decapitation secretion.
The outer layer of cells composing the cyst
wall is formed by myoepithelial cells.
Express human milk-fat globulin antigen,
while “true” eccrine hidrocystomas do not.
106. Histopathology of Apocrine Hidrocystoma
Cystic spaces appear empty because sweat is removed during processing.
Decapitation secretion often is seen in the lining.
107. Unilocular cyst containing clear
fluid, lined by ductal cells
composed of one to two layers
of cuboidal to flattened
epithelium.
Luminal protrusions ("apocrine
snouts") and myoepithelial cells
are absent.
109. Medical:
Topical 1% atropine in aqueous solution; Multiple eccrine
hidrocystomas may be treated with daily application, although lesions
reappear within days of discontinuing therapy.
Botulinum toxin A injections may be helpful.
Surgical:
Excision; punch, scissors, or elliptical.
Electrodesiccation; electrosurgical destruction of the cyst wall with a
fine tipped probe often is recommended to prevent recurrence.
Cryotherapy.
Laser; CO2 or pulsed dye laser.
110.
111.
112. Mucocele are usually the result of
trauma in the mouth disruption
of the ducts of minor salivary
glands an accumulation of
mucinous material a reactive
inflammatory response, and the
development of surrounding lining of
granulation tissue.
115. Mucoceles most frequently develop on the lower
labial mucosa (75% of cases), but they also
occur on the floor of the mouth, buccal
mucosa, and tongue.
They appear as smooth, soft, dome-shaped,
fluid-filled papules or nodules that are bluish or
translucent and range in size from a few
millimeters to over a centimeter.
Single or multiple but usually single.
In most cases of superficial mucocele lesions
tend to persist for several days or weeks,
rupture spontaneously (usually while eating).
116. It shows one or several spaces within the connective tissue
filled with mucinous material, but without an epithelial
lining.
The spaces are surrounded by chronic inflammation, mucin
containing macrophages, and granulation tissue.
A salivary duct may be seen at the periphery of these
findings.
Adjacent minor salivary glands may show chronic
inflammation and fibrosis.
The mucinous material is sialomucin, and the latter contains
both neutral and acid mucopolysaccharides, which stain
with PAS (diastase-resistant) and with Alcian blue or
colloidal iron, respectively.
117. Histopathology of Mucocele
well-delineated cavity that contains free mucinous material (blue arrow); this material
is characteristic of these entities. The cavity wall lacks an epithelial lining and is
considered a pseudocyst. The pseudocyst wall is composed of granulation
tissue (red arrow).
118. Histopathology of Mucocele
showing granulation tissue with collected mucin and inflammatory cells
(A: mucous acini, G: granulation tissue, M: mucin).
119. Mucoceles may resolve spontaneously especially
superficial mucocele and require no specific treatment.
If they do not, treatment options include;
1. Intralesional corticosteroid injection
2. Surgical excision
3. Marsupialization
4. Electrodesiccation
5. Cryosurgery
6. Laser ablation e.g. CO2
120.
121. There appear to be two variations;
I. The first is a form of focal mucinosis, a
condition characterized by abnormal deposits
of mucins in the skin. It shouldn't be called a
cyst as it does not have a surrounding
capsule, and is better termed a "pseudocyst".
II. The other variation arises from extension of
the lining of the distal interphalangeal joint
space and is due to osteoarthritis – a type of
ganglion. A pedicle connecting the cyst to
the adjacent joint space can usually be
demonstrated.
125. Most commonly occur on the dorsal
surface of the distal phalanx of the
fingers. Toe lesions are less commonly
observed.
These cysts have smooth shiny surface
and skin-colored to bluish and
translucent that drain clear gelatinous
material when punctured.
A characteristic depressed nail
deformity may be seen distal to the cyst .
126. Transillumination of a Mucous Cyst
A cyst is translucent, so a light shines through it. Note a longitudinal groove
in the nail.
127. Clefts are seen in the
dermis without an
epithelial lining. The
clefts and the surrounding
loose connective tissue
contain abundant acid
mucopolysaccharides,
which can be highlighted
by Alcian blue or
colloidal iron stains.
128. Treatments which may be successful include:
1. Repeatedly pressing firmly on the cyst.
2. Intralesional injection of corticosteroids.
3. Sclerosant injection
4. Cryotherapy.
5. Repeated puncture and drainage of a digital mucous cyst leads to
resolution in up to 70% of patients.
6. Surgical excision may give even higher success rates.
7. Identification and ligature of the connection to the joint capsule.
129.
130. Ganglions are among the most
common tumors of the hand and
wrist. For the most part, they are
asymptomatic masses that are
primarily cosmetic rather than
functional disturbances.
Ganglia are frequently attached to a
tendon sheath or the joint capsule,
but usually do not communicate with
the joint space.
134. They occur more commonly in women and
may cause discomfort with activity,
impairment of mobility, or cosmetic
concerns.
Soft cystic compressible, subcutaneous,
transilluminating, and slightly mobile
masses up to 4 cm in diameter without
associated skin changes that most
commonly occur on the dorsal aspect of the
wrist; they may also be found on the volar
wrist or fingers, the dorsal aspect of the feet,
or the knees.
135. Myxoid change is seen within
the connective tissue that
ultimately forms cystic
spaces. These spaces
coalesce into a dominant
cystic space lined by fibrous
tissue sometimes with a
synovial lining.
136. Early lesions may respond to several
weeks of compression therapy.
Other options include aspiration plus
intralesional corticosteroid injection
or excision.
Recurrences are common, even with
excisional therapy.