3. • Benign epithelial neoplasm
• common low-grade (unlikely to metastasize or
invade) skin tumor
• originates in the hair follicles epithelium above
the sebaceous glands
• Rapidly growing skin cancer
KERATOCANTHOMA
4. • Many pathologists consider it to be a form of squamous cell
carcinoma (SCC).
• The pathologist often labels KA as "well-differentiated squamous
cell carcinoma, keratoacanthoma variant", because about 6% of KA
manifest itself as squamous cell carcinoma when left untreated.
KERATOCANTHOMA
5. • Incidence is estimated at 1 in 1,000.
• Peak incidence occurs in those aged over 60 years.
• Is rare in young adults.
• It is uncommon in darker-skinned patients.
• Males are twice as often affected as females.
EPIDEMIOLOGY
6. • Sunlight and chemical carcinogens have been implicated.
• Trauma, genetic factors and immunocompromised status have also been
associated
• Industrial workers exposed to pitch and tar
• Long-term suppression of the immune system, such as organ transplant
recipients
• Long-term presence of scars, such as from a gasoline burn
• Chronic ulcers
• Presence of particular strains of the wart virus (human papillomavirus)
• Previous skin cancer
RISK FACTORS
7. • Typically rapid growth over a few weeks to months, followed by a slow
spontaneous resolution over 4-6 months (but may take up to 1 year).
• Most occur on sun-exposed areas, e.g the face, neck, and dorsum of hands
and forearms.
• They are usually solitary and begin as firm, round, skin-coloured or reddish
papule
• rapidly progress to dome-shaped nodules with a smooth shiny surface.
• A central crater of ulceration may develop, or a keratin plug that may
project like a horn.
• It leaves a residual scar if not excised.
• Occasionally presents as multiple tumors
CLINICAL FEATURES
8. • The defining characteristic of KA is that it is
dome-shaped, symmetrical, surrounded by a
smooth wall of inflamed skin, and capped with
keratin scales and debris.
• It always grows rapidly, reaching a large size
within days or weeks, and if untreated will starve
itself of nourishment, necrose (die), slough, and
heal with scarring.
CLINICAL FEATURES
9. The most common locations for keratoacanthoma include:
• Center of the face
• Backs of hands
• Forearms
• Ears
• Scalp
• Lower legs, especially in women
COMMON SITES
10. • Cells appear mature and dyskeratosis
• Central plug of keratin
• Surface epithelium at the lateral edge of tumor appears normal
• Sharply demarcated ,cup shaped buttress of normal epidermis
• Epithelium exhibiting pseudo-carcinomatous growth pattern
HISTOPATHOLOGY
11. • At the tip of the central crater an acute angle is formed
between the overlying epithelium and the periphery of the
lesion
• The central crater is filled with keratin and the base of the
crater
• Connective tissue exhibits moderate to marked infiltrate of
chronic inflammatory cells
HISTOPATHOLOGY
12. HISTOLOGICAL FEATURES:
• A crateriform structure with central
keratin and epidermal proliferation
without much atypia
• A lichenoid infiltrate of inflammatory
cells at the base
• Fibrosis of the papillary dermis
KERATOCANTHOMA, EARLY
13. • The pathology demonstrates a central plug of keratin producing an invagination of the epidermis.
There is a collarette of epidermis at the lateral margin of this low-power view of the lesion. The
epithelium is proliferative but well differentiated, often with a ground glass appearance and
marked keratinization
HISTOPATHOLOGY
15. Keratoacanthomas (molluscum sebaceum) may be divided into the following
types:
1-Giant Keratoacanthomas
are a cutaneous condition, a variant of keratoacanthomas, which in some instances may
reach dimensions of several centimeters.
2-Keratoacanthoma Centrifugum Marginatum
is a cutaneous condition, a variant of keratoacanthomas, which is characterized by multiple
tumors growing in a localized area.
3-Multiple Keratoacanthomas
(also known as "Ferguson–Smith syndrome," "Ferguson-Smith type of multiple self-healing
keratoacanthomas,") is a cutaneous condition, a variant of keratoacanthomas, which is
characterized by the appearance of multiple, sometimes hundreds of keratoacanthomas.
CLASSIFICATION
16. 4-Solitary Keratoacanthoma:
(also known as "Subungual keratoacanthoma") is a benign, but rapidly
growing, locally aggressive tumor which sometimes occur in the nail
apparatus.
5-Generalized Eruptive Keratoacanthoma
(also known as "Generalized eruptive keratoacanthoma of Grzybowski") is a
cutaneous condition, a variant of keratoacanthomas, characterized by
hundreds to thousands of tiny follicular keratotic papules over the entire body.
CLASSIFICATION
18. • Unfortunately, a shave biopsy will often reveal only keratin
fragments. A deep punch biopsy will often reveal a well
differentiated, mildly atypical, squamous cell suggestive of an
actinic keratosis or a squamous cell carcinoma. Only when the
pathologist has access to the entire lesion (not practical in many
circumstances) can a correct diagnosis be made
• Excisional or deep incisional biopsy is required to distinguish from
sqamous cell carcinoma
INVESTIGATIONS
19. • Electrodesiccation and Crettage often suffice.
• Excision of the entire lesion is often required if one wants to
confirm the clinical diagnosis of keratoacanthoma.
• RADIOTHERAPY:
Keratoacanthomas are radiosensitive and respond well to low doses
of radiation
Radiation therapy may be useful in selected patients with large
tumors when resection will result in cosmetic deformity for tumor's
that have recurred following attempted excision.
MANAGEMENT AND TREATMENT
