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Complications
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Local
• Wound sepsis, usually with Streptococcus pyogenes or Pseudomonas aeruginosa.
•
Scarring.
•
Wound contractures.
General
• Sepsis, particularly chest infection in inhalational
injury, urinary tract infection resulting from catheterization and septicaemia directly from wound
invasion.
• Acute peptic ulceration (Curling’s ulcer).
•
Seizures in children, owing to electrolyte
imbalance.
Acute kidney injury, resulting from the initial
•
hypovolaemia due to plasma loss, precipitation of
haemoglobin or myoglobin, or nephrotoxic antimicrobial agents.
• Psychological disturbance. Burn injuries are disproportionately sustained by children, the elderly
and patients with mental health conditions.
Patients with severe burns require assessment by a
Burns 85
psychiatric nurse or psychiatrist and often require
psychological support and treatment.
Prognosis
The prognosis from a major burn is dependent upon
the severity of the burn, total body surface area and
physiological reserve of the patient. Young infants
and the elderly carry a higher mortality than young
adults. Refinements in the protocols used for severe
burns, the organization of burn care to allow immediate access to expert advice and early transfer to a
major burns unit has resulted in improvements in the
survivability of major burns in younger patients (<50
years of age). Very few deaths occur during resuscitation, with most deaths now occurring due to later
complications, including sepsis.
Additional resources
Case 8: Burnt thorax
Case 9: Burn treatment
1111
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The skin andits adnexae
Amer J. Durrani
Learning objectives
✓ To understand the general functions of the skin.
✓ To understand the anatomy and embryology of the skin.
✓ To recognize the range of benign lesions and conditions that may
present in the skin.
✓ To distinguish between melanoma and non- melanoma skin cancers,
and premalignant skin lesions, their presentation and management.
skin surface. The basal layer is the layer of origin of
General functions ofthe
skin
The skin can be considered as the largest organ in the
body (16% total body weight in adults). It has multiple
protective functions: as a barrier to mechanical
trauma, chemical and thermal injury, and entry of
microorganisms. It has a metabolic function in regard
to vitamin D synthesis and a critical role in
thermoregulation.
Skin anatomy
andembryology
The skin has an outer epidermis, which is in a continuous state of regeneration. It is histologically
divided into five layers (Figure 11.1). Cells mature
from the basal layer to be shed as keratinocytes at the
Ellis and Calne’s Lecture Notes in General Surgery, Fourteenth Edition.
Edited by Christopher Watson and Justin Davies.
© 2023 John Wiley & Sons Ltd. Published 2023 by John Wiley & Sons Ltd.
Companion website: www.wiley.com/go/Watson/GeneralSurgery14
most skin cancers.
Below the epidermis, the dermis is subdivided into
a superficial layer (papillary dermis) and deep layer
(reticular dermis). The skin appendages are located
in the dermis and extend into subcutaneous fat. They
are structures from which tumours and inflammatory
skin conditions can arise (hair follicles, sebaceous,
eccrine and apocrine sweat glands, pain, temperature
and pressure receptors). The distinction between the
two layers of the dermis is also of importance when
considering burn injury and healing (Chapter10).
The dermis is a network of collagen that supports
the neurovascular supply to the skin and dermal
appendages. Elastin within the dermis provides
stretch and elastic recoil, and loss of these fibres contributes to the ageing process seen in the skin.
Hyaluronic acid and proteoglycans provide a gel to
facilitate metabolite diffusion in the dermis.
The hypodermis is the layer beneath the skin and
contains adipocytes, which provide insulation and
can act as an energy source.
The epidermis is derived from ectoderm and dermis from mesoderm. Merkel cells and melanocytes
originate from the neural crest (see later for malignant tumours derived from these cell types), and
Langerhans cells are of mesenchymal origin (involved
in cellular immunity).
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Stratum corneum
Stratum lucidum
Stratum granulosum Epidermis
Stratum spinosum
Stratum basale
Papillary dermis
Hair
follicle
Figure11.1 Layers of the skin with adnexal structures.
Sebaceous
glands
Sweat gland
Epidermoid cyst
An epidermoid cyst (commonly referred to incorrectly
as a sebaceous cyst) is a benign cyst that develops
from the upper portion of a hair follicle. They are
especially common on the scalp (pilar cyst), face,
scrotum and vulva, and on the lobe of the ear. The cyst
is fluctuant and cannot be moved separately from the
overlying skin. There may be a typical central
punctum (usually absent from a pilar cyst), and the
contents are ‘cheesy’ with an unpleasant smell
(keratin and cellular debris). The lining membrane
consists of epidermis- like epithelium.
Epidermoid cysts may also result from traumatic
implantation of epidermis into the subcutaneous tissue
(inclusion cyst, sometimes referred to as an implantation dermoid cyst). Typically, these are on the pulps of
fingers; there may be a healed scar overlying them.
Reticular dermis
Dermis
Subcutaneous
adipose tissue
Complications
• Infection.
• Calcification, producing a hard subcutaneous
tumour misnamed a ‘benign calcifying epithelioma’.
• Ulceration, which may then resemble a fungating
carcinoma (‘Cock’s peculiar tumour’
1
).
Treatment
An uninfected sebaceous cyst can be considered for
removal in order to prevent possible complications,
particularly the risk of infection. A small elliptical skin
incision is made around the punctum of the cyst
under local anaesthetic; the capsule is identified and
1
Edward Cock (1805–1892), Surgeon, Guy’s Hospital,
London, UK.
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the cyst removed intact. Failure to remove the cyst in
its entirety may lead to recurrence.
If the cyst is acutely inflamed and infected, incision
and drainage may be required and the wound allowed
to heal by secondary intention, with a course of oral
antibiotics. This may be followed later by subsequent
excision of the capsule wall if the cyst recurs.
Dermoid cyst
This is a congenital subcutaneous cystic swelling
resulting from an embryological nest of epithelial
cells along a line of fusion. The common sites are
over the external angular process of the frontal bone
(the external angular dermoid at the upper outer
margin of the orbit), the root of the nose (internal
angular dermoid) and in the midline. When in relation to the skull, the underlying bone is usually hollowed out around it. The possibility of communication
with an intracranial dermoid or the meninges should
be excluded by ultrasound and, if indicated, magnetic resonance imaging (MRI) scan prior to
excision.
Plantar warts
Otherwise known as verrucas, these occur on the
weight-
bearing areas of the foot. Pressure forces the wart
into the deeper tissues, producing intense local pain on
walking. They may occur in epidemics in schools and
other such places where the hygiene of the communal
bath or changing room is not of a high standard. They
should be treated by topical podophyllin or curettage.
Ganglion
A ganglion presents as a cystic, subcutaneous swelling that transilluminates brilliantly. It most commonly occurs around the wrist and dorsum of the foot
(joint capsule origin), or along the flexor aspect of the
fingers and on the peroneal tendons (tendon sheath
origin). Although ganglia are among the most common surgical lumps, their origin is uncertain. They
may represent a benign myxoma of joint capsule or
tendon sheath, a hamartoma or myxomatous degeneration due to trauma. They are thina synovial lining and contain clear colourless material
with a jelly-
like consistency.
walled cysts with
Verruca vulgaris (wart)
This is a well- localized horny projection that is common on the fingers, hands, feet and knees, particularly of children and young adults. Crops of warts may
occur on the genitalia and perianal region, in many
cases spread by sexual contact. Warts are often multiple and are due to a number of different strains of
human papilloma virus.
Microscopically, there is a local hyperplasia of the
prickle cell layer (stratum spinosum) of the skin
(acanthosis) with marked surface cornification.
Treatment
Untreated, warts usually vanish spontaneously within
2 years, hence the apparent efficacy of folklore ‘wart
cures’. Often, reassurance that these lesions will
disappear is all that is required, but if treatment is
demanded, they can be treated with topical application of silver nitrate, podophyllin, frozen with liquid
nitrogen or curetted under local or general
anaesthesia.
Treatment
The patient may complain of discomfort or of the cosmetic appearance; if so, the cyst should be excised
under a general anaesthetic using a bloodless field
produced by a tourniquet. The oldment of hitting the ganglion with the family bible ruptures the cyst, but recurrence usually occurs after
some time. Unfortunately, recurrence is also common after surgical excision.
fashioned treat-
Pilonidal sinus
The majority of pilonidal sinuses occur in the skin of
the natal cleft. They may be solitary or appear as a row
in the midline. Frequently, tufts of hair are found lying
free within the sinus (Latin pilus, hair; nidus, nest).
Usually, young adults are affected, males more
than females, and more often dark- haired individuals; the sinuses are rarely seen in children and do not
present until adolescence. They are an uncommon
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occupational disease of hairdressers, in whom
sinuses may occur in the clefts between the fingers.
They are very occasionally found in the axilla, at the
umbilicus, in the perineum and on the sole of the foot
as well as on amputation stumps.
Aetiology
The occurrence of pilonidal sinuses remote from the
natal cleft, and on the hands and feet of people working
with cattle, where the contained hair is clearly of animal origin, supports the hypothesis that these sinuses
occur by implantation of hair into the skin; these set up
a foreign body reaction and produce a chronic infected
sinus. It may be that, in some cases, postanal pits act as
traps for loose hairs, thus combining both the congenital and acquired theories of
skin follicles from its distal end and works its way in
due to tapered lateral hair extensions angled proximally, rather as a grass seed migrates up one’s sleeve.
origin. The hair enters the
Clinical features
The pilonidal sinus is asymptomatic until it becomes
infected; there is then a typical history of recurrent
abscesses, which either require drainage or discharge
spontaneously.
Treatment
1 Acute abscess. This is drained and allowed to heal
by secondary intention.
Quiescent sinus. The track is excised, treated with
2
injection of fibrin glue, or simply laid open and
allowed to heal by secondary intention. Recurrence
is diminished by keeping all incisions away from
the midline and keeping the surrounding skin free
from hair by shaving or the use of depilatory
creams. Laser treatment can be effective in reducing hair growth in the area. Following excision of
the sinus, particularly if it recurs after previous surgery, a local flap may be required with layered
wound closure, to reduce the risk of recurrence.
Hidradenitis suppurativa
Hidradenitis suppurativa is a chronic inflammatory
skin condition that affects apocrine gland- bearing
skin in the axillae, groin, and under the breasts.
Typically, patients present with persistent or recurrent abscesses, some of which may result in chronically discharging sinuses. Recurrent infections are
common, as is the resultant scarring. It is more common in women, usually starting during puberty; there
may be a family history (30–40% of patients) and it is
associated with obesity and cigarette smoking.
Treatment
Management of hidradenitis suppurativa should include
smoking cessation, weight control, wound care and pain
management. Topical therapies may be effective in mild
disease. Systemic antibiotics are frequently used for the
control of acute infective episodes, often in conjunction
with surgical incision and drainage. Medical therapy
with biological agents may be of benefit.
Conditions affecting
thenails
The nails are the site of some common and important
surgical conditions.
Paronychia
Paronychia denotes bacterial infection of the lateral
nail fold, usually of the finger, but it may complicate
an ingrowing toenail (see later in this chapter). An
acute paronychia is diagnosed when the nail fold is
red, swollen and tender, and pus may be visible
beneath the skin.
Treatment
If seen before pus has formed, while the nail fold is
cellulitic, purulent infection may be aborted by a
course of flucloxacillin or other appropriate antistaphylococcal antibiotic together with immobilization by a splint to the finger and elevation of the arm
in a sling. If pus is present, drainage is performed
through an incision carried proximally through the
nail fold, combined with removal of the base of the
nail if pus has tracked beneath it.
Chronic paronychia is seen in those whose occupation requires constant soaking of the hands in water, but
it may also occur as a result of fungal infection (Candida)
of the nails and where the peripheral circulation is deficient, as in Raynaud’s phenomenon (Chapter12).
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Ingrowing toenail
This is nearly always confined to the hallux and is
usually due to a combination of tight shoes
(particularly trainers) and the habit of paring the nail
downwards into the lateral nail fold, rather than
transversely; the sharp edge of the nail then grows
into the side of the nail bed, producing ulceration and
infection.
Treatment
If seen before infection has occurred, advice is given
on correct cutting of the nails; advice is also given to
avoid nylon socks and trainers. A small wick of cotton wool tucked daily into the side of the nail bed,
after preliminary soaking of the feet in hot water to
soften the nails, enables the nail to grow up out of
the fold.
If an acute paronychia is present, drainage will
be required by means of removal of the side of the
nail or avulsion of the whole nail. For recurrent
cases when the infection has settled, the affected
side may be excised together with the nail root
(wedge excision), or the entire nail may be obliterated completely by excision of the nail root
2
(Zadik’s
liquefied phenol, or a combination of the two
techniques.
operation) or by treating the nail bed with
Onychogryphosis
The nail is coiled like a ‘ram’s horn’. It may affect any
of the toes, although the hallux is the most common
site. It may follow trauma to the nail bed and is usually
found in elderly subjects.
Treatment
Relatively mild examples can be kept under control
by trimming the nail with bone- cutting forceps.
Merely avulsing the nail is invariably followed by
recurrence, and the only adequate treatment is excision of the nail bed.
Subungual haematoma
As a result of crush injury to the terminal phalanx, with
or without fracture of the underlying bone, a tense, painful haematoma may develop beneath the nail. Relief is
afforded by evacuating the clot through a hole made by
either a dental drill or a redcedures are painless. Occasionally, a small haematoma
may develop after a trivial or forgotten injury and clinically may closely simulate a subungual melanoma.
hot sterile needle; both pro-
Subungual exostosis
This is nearly always confined to the hallux and is
especially found in adolescents and young adults. It
appears as a reddishwhich is tender on pressure. The exostosis may ulcerate through the overlying nail, producing an infected
granulating mass. The diagnosis is confirmed by
X- ray of the toe, and treatment is to remove the nail
and excise the underlying exostosis.
brown area under the nail,
Subungual melanoma
The nail bed is a common site for malignant
melanoma (see later in this chapter). There is a long
history of slow growth and often a misleading history
of trauma. The lesion should be confirmed by removal
of the nail plate and excision biopsy followed by multidisciplinary team discussion and management with
the likely recommendation for wide local excision
(which may involve amputation of the digit) with sentinel node biopsy.
Glomus tumour
The nail beds of the fingers and toes are a common
site of this extremely painful lesion, which is a benign
tumour arising in a subcutaneous glomus body
(highly innervated arteriovenous anastomoses in
dermis responsible for temperature regulation). It is
considered later in this chapter.
Lesions ofthe nail bed
It is convenient to list a number of relatively common
conditions that affect the nail bed.
2
Frank Raphael Zadik (1914–1995), Orthopaedic Surgeon,
Leigh and Wigan, UK.
Tumours ofthe skin and
subcutaneous tissues
Classication
1 Epidermal.
a Benign: skin tag, keratoacanthoma and sebor-
rhoeic keratosis.
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b Premalignant: Actinic keratosis, Bowen’s dis-
ease and squamous cell carcinoma in situ.
Non- melanoma skin cancer: squamous cell
c
carcinoma, basal cell carcinoma and Marjolin’s
ulcer.
d
Secondary cutaneous deposits, e.g. from carci-
noma of breast, lung, kidney, leukaemia and
Hodgkin’s disease.
2
Pigmented skin lesions and malignant melanoma.
Tumours of sebaceous and sweat glands.
3
4
Dermal tumours from blood vessels, lymphatics,
nerves, fibrous tissue or fat.
Epidermal tumours
Skin tag (acrochordon)
This is a common, benign, pedunculated tumour,
often pigmented with melanin. Microscopically, it
comprises a keratinized papillary tumour of squamous epithelium.
Keratoacanthoma (molluscum
sebaceum)
This is a lesion that occurs in elderly patients, most
commonly men, in sun- exposed areas such as the
face and nose (75%), although it may occur on any
skin surface. It appears as a rapidly growing nodule,
which may reach 3cm or more in diameter in a few
weeks, with a characteristic central crater filled by a
keratin plug. It closely resembles a squamous carcinoma or rodent ulcer in appearance, and it is only the
history of very rapid growth that helps differentiate it
from the latter.
Histologically, it consists of a central crater filled
with keratin surrounded by hypertrophied squamous
stratified epithelium. There is no invasion of the surrounding tissues.
If left untreated, the lesion disappears over a period
of 4–5months, leaving a faint white scar. It appears to
be of hair follicle origin and may be associated with a
minor injury.
Treatment
It is safest to remove the lesion to establish histological proof of the diagnosis.
Seborrhoeic keratosis (basal cell
papilloma)
This is a common tumour occurring after the age of
40 years. It appears as a yellowish or brown raised
lesion on the face, arms or trunk, and is often multiple.
Table11.1 Fitzpatrick skin types
Skin
type Typical appearance
I Pale white skin, blue
eyes, red or blond hair
II Fair skin, blue eyes Burns easily, does
III Darker white skin Tans, after initial
IV Light-
V Brown skin Rarely burns, tans
VI Dark brown or black
It often appears greasy, and its surface is
by a network of crypts.
Microscopically, there is hyperkeratosis,
of the basal cell layer and melanin pigmentation.
The lesion is entirely benign, but if there is
diagnostic doubt on clinical examination and with a
dermatoscope, the exclusion of skin cancer can only
be made with certainty by incision or excision biopsy
and histological examination.
brown skin Burns minimally,
skin
Response to sun
exposure
Always burns, does
not tan
not tan
burn
tans easily
darkly easily
Never burns,
always tans
characterized
proliferation
Solar (actinic) keratosis
This is a small, hard, brown, scaly tumour on sunexposed areas of skin (e.g. the forehead, ears and
backs of hands) of the elderly. Keratoses are more
common in individuals with fair skin (Fitzpatrick skin
types I and II
prolonged exposure to ultraviolet light.
Microscopically, hyperkeratosis is present, often
with atypical dividing cells in the basal layer of the
epidermis.
The lesions may be treated with liquid nitrogen
cryotherapy or curettage; large areas may require topical chemotherapy (e.g. 5has also been used, and acts as an immune modifier,
stimulating an immune response with resolution of
the lesions.
3
omas Fitzpatrick (1919–2003), Dermatologist,
Massachusetts General Hospital, Boston. e Fitzpatrick
scale is a 6- point scale describing how dierent skin types
respond to sun exposure.
3
; Table 11.1) usually associated with
fluorouracil). Imiquimod
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The importance of this lesion is that it may undergo
change into a squamous cell carcinoma.
Bowen’s disease
Also known as intra- epidermal squamous cell carcinoma, this appears as a very slowly growing, red, scaly
plaque, and represents squamous carcinoma in situ.
It may be mistaken for a psoriatic plaque. Human
papillomavirus (HPV) DNA (particularly HPV16, but
also HPV2) has been found in some lesions.
Microscopically, atypical keratinocytes with vacuolization, mitoses and multinucleated giant cells are
prominent in the epidermis, but the basal layer is intact.
Treatment is excision; if left untreated, eventually a
squamous cell carcinoma will supervene.
4
Cutaneous squamous cell
carcinoma
This is the commonest form of skin cancer after basal
cell carcinoma, occurring on skin in areas exposed to
sunshine, such as the face and backs of the hands.
Like solar keratoses, it is relatively common in white
subjects (Fitzpatrick skin type I), with cumulative
lifetime sun exposure as the most significant risk
factor. Incidence increases after the age of 40 years
and the male:female ratio is 3:1.
Predisposing factors
These include the following.
Solar keratosis.
•
• Bowen’s disease.
• Exposure to sunshine or ultraviolet irradiation.
Exposure to ionizing irradiation.
•
• Infection with human papilloma virus subtypes
6and 11.
• Carcinogens, e.g. pitch, tar, soot and mineral oils.
• Chronic ulceration, particularly in burns scars
(Marjolin’s ulcer– see below).
• Immunosuppressive drugs, e.g. azathioprine and
ciclosporin.
Pathology
Macroscopically, it presents as a typical malignant
ulcer with indurated, raised, everted edges and a
central scab.
Microscopically, there are solid columns of epithelial cells growing into the dermis with epithelial pearls
of central keratin surrounded by prickle cells.
Occasionally, anaplastic tumours are seen, in which
these pearls are absent.
Spread occurs by local infiltration and then via lymphatics. Bloodadvanced cases.
borne spread occurs only in very
Treatment
A tissue diagnosis with either an incision or excision
biopsy is mandatory. Subsequent treatment may consist of a wider excision, which may necessitate a
reconstruction (skin graft and local flap) depending
on the site and size of the lesion. Adjuvant radiotherapy may be required based on the histological characteristics of the primary tumour. If the regional lymph
nodes are involved, block dissection is indicated.
Marjolin’s ulcer
This is the name applied to malignant change in a
scar, ulcer or sinus, for example, a chronic venous
ulcer, an unhealed burn or the sinus of chronic osteomyelitis. It has the following characteristics:
•
slow growth, because the lesion is relatively
avascular;
painless, because the scar tissue does not contain
•
cutaneous nerve fibres;
•
lymphatic spread is late, because the scar tissue
produces lymphatic obliteration.
Once the tumour reaches the normal tissues
beyond the diseased area, rapid growth, pain and
lymphatic involvement take place.
5
Basal cell carcinoma
(rodentulcer)
This is the most common form of skin cancer in white
people (80% of nonoccurs usually in elderly subjects, in males twice as
commonly as in females. Ninety percent are found on
the face above a line joining the angle of the mouth to
the external auditory meatus, particularly around the
eye, the nasolabial folds and the hairline of the scalp.
The tumour may, however, arise on any part of the
melanoma skin cancers). It
4
John Templeton Bowen (1857–1941), Dermatologist,
Harvard Medical School, Boston, MA, USA.
5
Jean Nicholas Marjolin (1780–1850), Surgeon, Hôpital
Sainte- Eugénie, Paris, France.
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skin, including the anal margin. Predisposing factors
are exposure to sunlight or irradiation.
Pathology
Macroscopically and on examination with a dermatoscope, the tumour has raised, rolled but not everted
edges. It consists of pearly nodules over which fine
blood vessels can be seen to course (telangiectasia).
Starting as a small nodule, the tumour very slowly grows
over the years with central ulceration and scabbing.
Microscopically, solid sheets of uniform, darkly
staining cells arising from the basal layer of the skin are
seen. Prickle cells and epithelial pearls are both absent.
Spread is by local infiltration, with slow but steady
destruction of surrounding tissues; in advanced
cases, the underlying skull may be eroded, or the face,
nose and eye may be destroyed, hence the name
‘rodent’. Lymphatic and blood- borne spread occur
with extreme rarity.
Treatment
Treatment is by surgical excision, with an adequate
measured margin, with reconstruction if required
(skin graft or local flap). At anatomical sites where this
may prove challenging, i.e. for high risk tumours at
high risk sites (e.g. eyelid, periorbital and nasal areas),
6
Mohs
micrographic surgery offers the lowest risk of
tumour recurrence. It is also indicated in late cases
where the tumour has recurred after irradiation or
has invaded the underlying bone or cartilage.
Adjuvant radiotherapy may be required or used as a
primary treatment depending on patient and tumour
factors following a multidisciplinary discussion.
Pigmented skin lesions
andmalignant melanoma
Benign pigmented skin lesions
• Intradermal melanoma or naevus (the common
mole).
6
Frederic Edward Mohs (1910–2002), Surgeon, University
of Wisconsin. Pioneered the concept of rapid histological
examination at the time of tumour excision to ensure
complete tumour excision while allowing maximal
preservation of healthy tissue.
• Junctional melanoma or naevus.
Compound melanoma or naevus.
•
•
Spitz naevus.
•
Malignant melanoma.
Nearly everyone possesses one or more moles;
some have hundreds, although they may not become
apparent until after puberty. Those moles that are
entirely within the dermis remain benign, but a small
percentage of the junctional naevi, so called because
they are seen in the basal layer of the epidermis at its
junction with the dermis, may undergo malignant
change (Figure11.2).
Intradermal melanoma or naevus
This is the most common variety of mole. The naevus
may be light or dark in colour and may be flat or
raised, hairy or hairless. A hairy mole is nearly always
intradermal. They may be found in any place in the
body except the palm of the hand, the sole of the foot
or the scrotal skin.
Histologically, there is a nest of melanocytes situated entirely within the dermis where the cells form
encapsulated masses. They never undergo
nonmalignant change, and need no treatment unless the
diagnosis is uncertain.
Junctional melanoma or naevus
The junctional naevus is pigmented to a variable
shade from light brown to almost black. It is nearly
always flat, smooth and hairless. It may occur anywhere on the body and, unlike the intradermal naevus, may be found on the palm of the hand, sole of the
foot and the genitalia.
Histologically, naevus cells are seen in the basal
layers of the epidermis from which the cells may
spread to the surface.
Only a small percentage of junctional naevi
undergo malignant change, but it is from this group
that the vast majority of malignant melanomas
arise.
Compound melanoma or naevus
Clinically, this is indistinguishable from the
intradermal naevus, but histologically, it has junctional elements that make it potentially malignant. It may be darker and palpable due to a raised
border.
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(a) Normal (b) Intradermal melanoma
(c) Junctional melanoma (d) Malignant melanoma
Figure11.2 (a) The normal skin contains melanocytes (shown as cells) and melanin pigment shown as dots. The
pigment increases in sunburn and freckles. (b) A benign intradermal naevus; the melanocytes are clumped together in
the dermis to form a localized benign tumour. (c) A junctional naevus with melanocytes clumping together in the basal
layer of the epidermis. (d) These are usually benign but may occasionally give rise to an invasive malignant melanoma.
Spitz naevus
Spitz naevus is an uncommon type of mole
(melanocytic naevus) that usually affects young
people and children, hence it used to be known as a
juvenile melanoma. It is a benign skin tumour, but it
may resemble a malignant melanoma clinically and
microscopically, so Spitz naevi are often excised as a
precaution.
7
Sophie Spitz (1910–1956), Pathologist, Memorial Sloan
Kettering Cancer Centre, NewYork, NY, USA.
7
Malignant melanoma
Malignant melanomas develop from melanocytes,
which are situated in the basal layer of the epidermis
and originate from the neuroectoderm of the embryonic neural crest. Some melanomas contain no visible pigment (amelanotic melanoma). While most
melanomas arise in the skin, they may also occur at
other sites to which neural crest cells migrate, in particular the pigmented choroid layer of the eye.
Malignant melanomas can arise de novo or in preexisting naevi, either junctional naevi or compound
naevi where there is a junctional component. They
mainly occur in fair- skinned people on light- exposed
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