Skin and Soft Tissue Lesions

Chapter 2
Skin and Soft Tissue Lesions



  1. Benign nonpigmented skin lesions
  2. Benign pigmented skin lesions
  3. Malignant nonpigmented skin lesions
  4. Malignant melanoma
  5. Vascular anomalies
  6. Soft tissue tumours
  7. Bone sarcomas
  8. Further reading

Benign nonpigmented skin lesions


Skin lesions can derive from any of the constituents of skin:



  • Epidermis:

    • Keratinocytes
    • Melanocytes
    • Merkel cells

  • Dermis:

    • Hair follicles
    • Sebaceous glands
    • Apocrine glands
    • Eccrine sweat glands
    • Neural tissue

  • Miscellaneous:

    • Epidermoid cysts
    • Pilar cysts
    • Milia
    • Xanthelasma.

Skin lesions of epidermal origin


Seborrhoeic keratosis



  • Common; also known as basal cell papilloma.
  • Greasy plaque-like lesion usually found on the torso of elderly patients.
  • Treated by curettage.

Squamous papilloma



  • Common; also known as a ‘skin tag’ or ‘acrochordon’.
  • Treated by excision.

Viral wart



  • Caused by epidermal infection with human papilloma virus (HPV).
  • Treated by cryotherapy, curettage or laser.

Actinic (solar) keratosis (AK)



  • Scaly, crusted area; typically occurs on sun-exposed areas in the elderly.
  • Recent evidence suggests AK is part of a spectrum from sun-damaged skin to squamous cell carcinoma (SCC) in situ.

    • 0.1% per year progress to SCCs
    • 15–25% per year spontaneously regress.

  • Treatment, if indicated, is by cryotherapy, photodynamic therapy (PDT), or topical preparations of imiquimod, diclofenac or 5-fluorouracil (5-FU).

Keratin horn



  • Hard, protruding lump of cornified material—proliferation of keratin.
  • The base is benign in 50%, malignant in 20% (usually SCC) and AK in 30%.
  • To rule out malignancy, biopsy should include the base of the horn.

Bowen’s disease



  • First described by the American dermatologist John T Bowen (1912).
  • Red scaly lesion usually found on the legs of elderly patients.
  • Histologically resembles SCC, but abnormalities are limited to epidermis.

    • Therefore, best regarded as in situ SCC.

  • 3–5% develop into invasive SCCs.
  • Treatment options: cryotherapy, curettage, excision, topical 5-FU, imiquimod, PDT.

Keratoacanthoma (KA)



  • Benign epithelial tumour of pilosebaceous origin composed of keratinising squamous cells.
  • Characterised by rapid evolution (weeks or months) into a nodule with a central keratotic core.
  • Followed by spontaneous involution to leave a depressed scar, usually within 4–6 months.
  • Histologically difficult to differentiate from SCCs.
  • Some maintain they are well-differentiated SCCs rather than a distinct entity.
  • Familial forms of KA include:

    • Ferguson–Smith syndrome
    • Muir–Torre syndrome.

Ferguson–Smith syndrome


  • Linked to a single gene mutation on chromosome 9, characterised by:

    • Autosomal dominant inheritance
    • Multiple self-healing epitheliomas, which look and behave like KAs.

  • Most patients can trace their ancestry to a family living in Western Scotland in the 18th century.

Muir–Torre syndrome


  • Described by Muir (1967), then Torre (1968).
  • Autosomal dominant inheritance in ⅔ of cases, often with a germline mutation in one of the DNA mismatch repair genes hMLH1 or hMSH2.
  • Characterised by:

    • One or more sebaceous neoplasms (sebaceous adenoma, sebaceous epithelioma, sebaceous carcinoma) or KAs
    • One or more visceral malignancies (usually gastrointestinal or genitourinary carcinomas).

Skin lesions of dermal origin



  • Over 80 different adnexal tumours described.
  • Most are benign, with a rarer malignant counterpart.
  • Classified histologically according to their predominant morphological component.

Lesions with hair follicle (pilar) differentiation


Trichoepithelioma


  • Translucent pinky-white nodules.
  • Often located around nose and mouth; may run in families.
  • Can be difficult to distinguish from basal cell carcinomas (BCCs).

Trichofolliculoma


  • Nodules with a central pore that often contains white hairs.
  • Histologically resemble BCCs.
  • However, unlike BCCs, they contain keratin-filled macrocysts.

Trichoblastoma


  • Typically a slow-growing solitary nodule in the head and neck.
  • Commonly mistaken (clinically and histologically) for trichoepithelioma and BCC.

Trichilemmoma


  • Small, skin-coloured, warty papules usually found on the face.
  • Multiple trichilemmomas are diagnostic of Cowden’s disease.

Cowden’s disease


  • Autosomal dominant; thought to be due to germline mutations in the tumour suppressor gene PTEN.
  • Characterised by multiple hamartomas and high risk of breast, endometrial and thyroid carcinoma.
  • Mucocutaneous lesions affect over 90% of patients:

    • Facial trichilemmomas
    • Acral keratoses
    • Oral papillomatous papules and mucosal cobblestoning.

  • Hamartomatous polyps of the intestinal tract found in 40–60% of patients.

Pilomatrixoma


  • Also known as calcifying epithelioma of Malherbe.
  • Arises from outer root sheath cells of hair follicles.
  • Typically, a solitary rock-hard subcutaneous nodule on the face of children.

    • 40% develop in the first decade of life; another 20% develop in the second decade.
    • Most common in head and neck; may occur on arms, trunk and legs.
    • Periocular tissues involved in 10–17%; 5% of cases are multifocal.

  • 75% have mutations in the CTNNB1 gene that codes for β-catenin.
  • Malignant change is rare.
  • Treated by excision.

Lesions with sebaceous gland differentiation


Sebaceous naevus


  • Also known as sebaceous naevus of Jadassohn, or organoid naevus.
  • Typically present at birth; may enlarge and become raised in puberty due to sebaceous gland hyperplasia.
  • Scalp lesions often excised on aesthetic grounds because they cause a bald patch.
  • Some excise these because of a 15% chance of transformation into a secondary tumour:

    • Usually syringocystadenoma papilliferum (SCAP), trichoblastoma or trichilemmoma.
    • Less common—malignant transformation into BCC, SCC, malignant appendigeal tumour.

  • Many advocate clinical follow-up rather than excision:

    • Most secondary tumours arise in adulthood; most are benign.

Sebaceous gland hyperplasia


  • Small yellowish papules; usually found on the face.
  • Dermoscopy helps differentiate between this and BCC.
  • Rhinophyma is severe sebaceous hyperplasia of the nose.

Sebaceous adenomas


  • Small smooth papules; usually occur on the scalp of the elderly.

Lesions with sweat gland differentiation


Poroma


  • Relatively common; present as small nodules on palms or soles of adults.

Cylindroma


  • Pink lesions; usually occur on scalps of the elderly.
  • Large or multiple lesions known as ‘turban tumours’.

Syringoma


  • Small, skin-coloured dermal papules.
  • Typically occur on the eyelid and chest of women.
  • A subtype of syringoma is associated with Down’s syndrome.

Syringocystadenoma papilliferum (SCAP)


  • Solitary papule or smooth hairless plaque on scalp and forehead.
  • May occur de novo or in association with sebaceous naevus.

Hidrocystoma


  • Cystic lesion; typically occurs on the face.
  • Can differentiate into apocrine and eccrine subtypes.

Lesions derived from neural tissue


Neurofibroma


  • Skin-coloured nodule composed of neural tissue and keratin.
  • Arises from nonmyelinating Schwann cells; often incorporates other cell types.
  • Classified into dermal and plexiform subtypes:

    • Dermal (cutaneous) neurofibromas are associated with a single peripheral nerve.
    • Plexiform neurofibromas are associated with multiple nerve bundles.

  • Plexiform neurofibromas are large infiltrative lesions usually found in the head and neck.
  • Two types of plexiform neurofibroma:

    1. Nodular
    2. Diffuse.

  • Diffuse form also known as elephantiasis neurofibromatosa.

    • Characterised by wrinkled, pendulous appearance due to overgrowth of skin and subcutaneous tissue.

  • Wound complications are common following excision.
  • Neurofibromas can occur as solitary lesions or associated with neurofibromatosis (NF).
  • This is discussed further in Chapter 3, ‘Craniofacial surgery > Neoplasia–hyperplasia’.

Neurilemmoma


  • Also known as schwannoma; composed solely of myelinating Schwann cells.

    • Therefore, more homogeneous than neurofibroma.

  • Encapsulated tumours; can be separated from the parent nerve, unlike neurofibroma.
  • Multiple neurilemmomas should raise the possibility of NF.

Miscellaneous


Inclusion cysts



  • Implantation cysts result from trapping a segment of epidermis within dermis following trauma.

Dermoid cysts



  • Occur following entrapment of embryonic epithelium at sites of fusion during facial development.
  • Usually submuscular; found towards the outer corner of the eye (angular dermoids) or in the midline between forehead and nasal tip (central dermoids).
  • Also found more posteriorly, associated with the anterior fontanelle.
  • Central dermoids may have deep intracranial extensions.

    • Preoperative radiological assessment is recommended.

Epidermoid cysts



  • Most common superficial cysts; often incorrectly referred to as sebaceous cysts.
  • Firm subcutaneous swellings attached to skin.
  • May have an overlying punctum; frequently located in the cheek.
  • Histologically, consist of stratified squamous epithelium surrounding keratinised material, as well as sebum secreted by sebaceous glands.
  • Treated by excision of the cyst with the overlying punctum.
  • Incomplete excision can result in recurrence.

Gardner syndrome


  • Autosomal dominant, characterised by a triad of:

    1. Familial polyposis coli with 100% risk of malignant transformation
    2. Multiple skin and soft tissue tumours

      • Epidermoid cysts, desmoid tumours, other benign tumours.

    3. Jaw osteomas.

Pilar cysts



  • Also known as trichilemmal cysts.
  • Similar to epidermoid cysts but derive from the outer root sheath of hair follicles.
  • Typically occur on the scalp.
  • Most occur sporadically; some are autosomal dominant.
  • Treated by surgical excision.

Milia



  • Small, keratin-filled intraepidermal cysts.
  • Usually occur on the cheeks.
  • In children, they typically disappear on their own.
  • In adults, they may require treatment by needle enucleation.

Xanthelasma



  • Represent accumulation of lipid within the skin.
  • Usually located around the eyes as thin, well-demarcated plaques.
  • Xanthelasmata that become large or nodular are called xanthomas.
  • Myocardial infarction, ischaemic cardiovascular disease and death are commoner in patients with xanthelasmata than in those without.

    • Serum lipids should be checked: 50% will have hypercholesterolaemia.

  • Removal is accomplished by excision, laser or topical trichloroacetic acid peel.

Benign pigmented skin lesions


Structure and function of melanocytes


Melanocytes



  • Derived from the neural crest.
  • Spindle-shaped clear cells with dendritic processes and dark nucleus.
  • The number of melanocytes does not vary between races.

Melanin



  • Synthesised within melanocytes from the amino acid tyrosine, via the intermediate Dopa.
  • Accumulates in vesicles within melanocytes called melanosomes.
  • Melanosomes are distributed to surrounding cells via long dendritic processes.

    • Reminiscent of synaptic transmission, reflecting neural crest origins.

  • Once inside the keratinocyte, melanin is orientated over the external-facing surface of the nucleus like a sun shade.
  • Cells around melanocytes usually contain more melanin than the melanocytes themselves.
  • Increased pigmentation of dark-skinned people is due to increased basal production of melanin.
  • Melanin production is stimulated by UVB light and melanocyte-stimulating hormone (MSH).

Naevus cells



  • When melanocytes leave the epidermis and enter the dermis they become naevus cells.
  • Naevus cells differ from melanocytes:

    • Round rather than spindle shaped
    • No dendritic processes
    • Tend to congregate in nests.

Melanocytic lesions



  • In loose terms, a ‘naevus’ is any congenital skin lesion, ‘mole’ or ‘birthmark’.
  • In pathological terms it is a well-circumscribed hamartoma of skin or oral mucosa, not due to external causes.
  • A naevus (singular) or naevi (plural) may involve epidermal, connective, adnexal, neural or vascular tissues.
  • Naevi are benign by definition, but malignancies can arise from them.
  • Most use the term ‘naevus’ to describe pigmented naevi.
  • Benign melanocytic lesions either contain naevus cells or melanocytes:

    • Naevus cell naevi can be congenital or acquired.
    • Melanocytic naevi originate in either epidermis or dermis.

  • Melanocytic lesions can be benign or malignant.

    • Malignant melanocytic lesions are melanomas; also known as malignant melanomas.

Classification


Naevus cell naevi



  • Congenital

    • Giant congenital melanocytic naevus (CMN)
    • Non-giant CMN

  • Acquired

    • Junctional naevus
    • Compound naevus
    • Intradermal naevus

  • Special naevi

    • Spitz naevus
    • Atypical naevus
    • Halo naevus.

Melanocytic naevi



  • Epidermal

    • Ephelis
    • Lentigo
    • Café-au-lait patch
    • Becker naevus
    • McCune–Albright syndrome

  • Dermal

    • Blue naevus
    • Mongolian blue spot
    • Naevus of Ota
    • Naevus of Ito.

Congenital naevus cell naevi


Congenital melanocytic naevi



  • Brown or black lesions present at birth.
  • Classified as ‘giant’ if projected to be >20 cm diameter in adulthood.
  • Giant CMN are sometimes called giant hairy naevi.
  • Annual incidence for all sizes of CMN is approximately 2%.
  • Giant CMN is much rarer—annual incidence 1 in 20,000.
  • Significant risk of central nervous system (CNS) abnormalities with CMN of any size:

    • Disorders of CNS development
    • Intracranial melanosis
    • Nonmelanotic intracranial abnormalities.

Rationale for treatment


  • Two factors historically influenced CMN treatment:

    1. Risk of malignant transformation
    2. Aesthetic appearance.

Risk of malignant transformation


  • Lifetime risk of malignant change within CMN is controversial:

    • Previous studies reported risk of melanoma up to 45%.
    • More recent prospective reports show risk of melanoma is 0.7–2.4%.

  • Median age at diagnosis of melanoma is 7 years.
  • Risk of malignancy seems to be associated with increasing CMN size.
  • A significant proportion of melanomas in CMN patients arise outside the CMN, and even outside the skin.
  • Both benign and malignant leptomeningeal melanosis, associated with CMN, carry poor prognosis.
  • Risk factors for associated neurocutaneous melanosis:

    • Multiple satellite naevi.
    • Signs of abnormal neurodevelopment, including seizures.
    • CMN in the midline of the trunk and calvarium.
    • Projected adult size >40 cm.

  • Patients with risk factors should be screened by CNS magnetic resonance imaging (MRI) before 6 months of age.

Aesthetic appearance


  • Many CMNs lighten spontaneously over the course of years.

    • A few become darker, hairy and nodular, causing aesthetic and oncological concerns.

  • This should be explained to patients considering treatment.

Treatment


  • The best treatment of CMN is controversial.
  • Surgery to reduce malignancy risk is fallacious.
  • Nevertheless, some believe naevus cells are located superficially in the neonatal period and become deeper thereafter—termed ‘Abtropfung’ by Unna (1893).
  • Applying this belief, naevus cells can easily be removed by curettage and dermabrasion if done in the first few days or weeks of life.

    • However, this opinion is based on an outdated view of melanocyte migration.

  • Neonatal surgery is hazardous with a narrow window of permissible blood loss.
  • Following this kind of superficial surgery, there may be difficulty in monitoring changes in the residual naevus cells, which lie deeper in the dermis.
  • The current practice of the multidisciplinary team (MDT) at Great Ormond Street Hospital, London is summarised as:

    • No surgery offered for risk reduction.
    • Routine surgery postponed until after the first year, when risks of anaesthesia are lower.
    • Serial annual photography to assess spontaneous lightening.
    • Surgery for cosmetic reasons may be offered to:

      • Those with facial CMN
      • Those with a single, easily excisable CMN.

Acquired naevus cell naevi



  • Rare in infancy.
  • Incidence increases steadily during childhood, sharply during adolescence, more slowly in early adulthood and plateaus in middle age.
  • There are three main types of acquired naevus cell naevi.

Junctional naevi



  • Flat, smooth, irregularly pigmented lesions.
  • Usually found in the young.
  • Nests of naevus cells clustered at the dermoepidermal junction.

Compound naevi



  • Round, well-circumscribed, slightly raised lesions.
  • Nests of naevus cells clustered at the dermoepidermal junction extending into dermis.

Intradermal naevi



  • Dome-shaped lesions; may be nonpigmented or hairy.
  • Tend to occur more in adults.
  • Nests of naevus cells clustered solely within dermis.

Special naevus cell naevi


Spitz naevi



  • Benign lesions; also known as epithelioid cell naevi.
  • The misleading term ‘juvenile melanoma’ should no longer be used because:

    • They can occur in adults.
    • They are not melanomas.

  • Usually present in early childhood as firm reddish-brown nodules.
  • Histologically, they share features common to all melanocytic naevi.
  • Treated by excision with narrow margins.
  • Histological examination distinguishes Spitz naevus from:

    • Atypical Spitz naevus (spitzoid tumour of uncertain biological potential)

      • Borderline lesion—does not satisfy criteria for either Spitz naevus or frank melanoma.

    • Malignant Spitz naevus (spitzoid melanoma)

      • This is frankly malignant.

Atypical naevi



  • Can occur sporadically or run in families.
  • Diagnosed based on defined criteria, as discussed in ‘Malignant melanoma > Premalignant lesions’.

Halo naevi



  • An otherwise normal melanocytic naevus with a peripheral area of depigmentation.
  • Depigmentation represents regression due to immunological factors.

    • Anti-melanoma antibodies detected in some patients.

  • Relatively common in older children and teenagers.
  • Tend to regress leaving a small scar.
  • Treatment is expectant.

Epidermal melanocytic naevi


Ephelis



  • Commonly known as a freckle.
  • Contains a normal number of melanocytes.
  • Pigmentation is due to increased melanin production.
  • Lesions are said to disappear in the absence of sunlight.

Lentigo



  • Contains an increased number of melanocytes.
  • Persists in the absence of sunlight.
  • Different types of lentigo have been described, including:

    • Lentigo simplex—occurs in the young and middle aged
    • Lentigo senilis—occurs in the elderly
    • Solar lentigo—occurs after sun exposure.

Café-au-lait patch



  • Pale brown macule.
  • Histologically there are ‘macromelanosomes’ in basal melanocytes.
  • Six or more >5 mm in children (>15 mm in adults) required to support a diagnosis of NF1.

Becker naevus



  • Described by the American dermatologist Samuel William Becker (1948).
  • Dark patch on the chest, shoulder or back.
  • Normally appears during adolescence; may become hairy.
  • Predominantly affects males.

McCune–Albright syndrome



  • Characterised by the triad of:

    1. Café au lait macules
    2. Polyostotic fibrous dysplasia
    3. Endocrine dysfunction with precocious puberty.

Dermal melanocytic naevi



  • Characterised by presence of melanocytes within the dermis.

Blue naevus



  • Appears as a round area of blue-black discolouration.
  • Two variants:

    1. Common blue naevus, usually <1 cm in diameter
    2. Cellular blue naevus, usually >1 cm in diameter.

  • Thought to result from arrested migration of melanocytes bound for the dermoepidermal junction.

Mongolian blue spot



  • Characterised by blue-grey pigmentation over the sacrum.
  • Said to be present in 90% of Mongolian infants.
  • Can be mistaken for bruising and attributed to nonaccidental injury of children.

Naevus of Ota



  • Described by Ota and Tanino (1939).
  • Bluish pigmentation on the face in the distribution of the ophthalmic and maxillary divisions of the trigeminal nerve.
  • May also involve ocular and oral mucosal surfaces.
  • Causes glaucoma in up to 10% of patients.
  • Uncommon in Caucasians; prevalent among Japanese.

Naevus of Ito



  • Described by Minor Ito (1954).
  • Blue-grey discolouration in the shoulder region.
  • Rare in Caucasians; common among Japanese.

Malignant nonpigmented skin lesions



  • Nonpigmented skin cancer is the most common malignancy in the Western world:

    • BCC
    • SCC
    • Merkel cell carcinoma (MCC)
    • Sebaceous carcinoma.

Aetiology


Premalignant conditions



  • Bowen’s disease
  • AKs
  • Sebaceous naevi
  • Leukoplakia
  • Erythroplakia.

Radiation



  • UVA and UVB both associated with development of skin malignancy.
  • Ionising radiation, often iatrogenic.

Immunosuppression



  • Hampers cell-mediated immunity.
  • Reduces the number and activity of natural killer (NK) cells.

Chronic wounds



  • Marjolin’s ulcer is SCC arising within an area of chronic inflammation.

    • Classically presents as unhealed areas within venous ulcers, old burns, chronic sinuses.

Toxins



  • Soot—historically, high incidence of scrotal cancer in chimney sweeps.
  • Arsenic—an ingredient of Bell’s Asthma Medicine and Fowler’s solution.

Genetic


Xeroderma pigmentosum


  • Deficiency of thiamine dimerase.
  • Thiamine absorbs UV light and forms dimers.

    • These dimers cannot be broken down due to the enzyme deficiency.

  • Buildup of thiamine dimers induces defects in DNA and carcinogenesis.

Albinism


  • Characterised by absence of melanin.
  • Skin is particularly sensitive to UV light.

Fair skin


  • Fitzpatrick classified skin type based on colour and response to UV light:

    • Type I: pale white skin, always burns, never tans.
    • Type II: white skin, always burns easily, tans minimally.
    • Type III: light brown skin, burns moderately, tans uniformly.
    • Type IV: moderate brown skin (Mediterranean complexion), burns minimally, always tans well.
    • Type V: dark brown skin (Indian complexion), rarely burns, tans profusely.
    • Type VI: deep brown to black skin, never burns.

  • Fitzpatrick type I and II skin have a higher incidence of skin cancer.

Basal cell carcinoma (BCC)



  • A slow-growing, locally invasive malignant epidermal skin tumour.
  • Usually emerges from keratinocyte stem cells in hair follicles, sebaceous glands or interfollicular basal cells.
  • BCC was known as mariner’s disease in the 19th century.
  • In France, it was known as ‘cancer des cultivateurs’.

Epidemiology



  • Most common neoplasm in Caucasians in the Western world.
  • 85% occur after 40 years of age.
  • 80% occur in sun-exposed sites of the face, head and neck, arms and dorsal hands.
  • Over 300 cases of metastatic BCC are reported.

Pathogenesis



  • Most cases are sporadic.

    • Associated with sun exposure, particularly UVB.

  • UV radiation induces gene mutations, notably in p53 and PTCH1.

    • The hedgehog pathway is affected by mutations in these tumour suppressor genes.
    • Gorlin’s syndrome and xeroderma pigmentosum have mutations in these genes.

  • UV-induced inflammation of the skin is also thought to contribute to pathogenesis.

Histological appearance



  • Composed of sheets or nests of small round basophilic cells.
  • Peripheral palisading of nuclei at the margins of cell nests.
  • Inflammatory infiltrate and ulceration may also be seen.

Classification



  • 26 histopathological types described by Wade and Ackerman (1978).
  • The three types common to all published studies, accounting for 90% of all types:

    • Nodular (30–75%)
    • Superficial (10–15%)
    • Infiltrative (10%).

Prognostic factors



  • BCCs are stratified into high or low risk of recurrence following treatment.
  • Increased risk of local recurrence is caused by:

    • Patient factors
    • Macroscopic features
    • Microscopic features.

Patient factors


  • Immunosuppression.

Macroscopic features


  • Increasing tumour size.
  • Location: central face, especially around eyes, nose, lips and ears.
  • Poorly defined lesions.

Microscopic features


  • Histological subtypes—infiltrative and morphoeic are high risk.
  • Perineural or perivascular involvement.
  • Recurrent lesions.

Basal cell naevus syndrome



  • Also known as Gorlin’s syndrome, or Gorlin–Goltz syndrome.
  • Autosomal dominant; associated with germline mutations in PTCH gene.
  • Characterised by some or all of the following:

    • Multiple BCCs that appear at an early age
    • Palmar and plantar pits
    • Odontogenic keratocysts, more common in mandible than maxilla
    • Bifid ribs
    • Calcification of the falx cerebri
    • Overdevelopment of supraorbital ridges with mild hypertelorism
    • Learning difficulties affect 5% of cases.

  • Associated with congenital blindness, hypogonadism and 75% of females develop ovarian fibromas.
  • Also increased incidence of CNS tumours, including medulloblastoma.

    • Medulloblastoma occurs in childhood and may therefore be the presenting feature of Gorlin’s.

Treatment of BCC



  • Nonsurgical
  • Surgical, which may be:

    • Destructive—curettage and cautery, cryotherapy, laser
    • Nondestructive—excision.

  • Most plastic surgeons are concerned with excisional techniques.

Surgical treatment


  • Most are treated by excision with predetermined margins.
  • Deep margin should be into subcutaneous fat as a minimum.
  • Peripheral margins for well-defined lesions <2 cm:

    • 3 mm clears the tumour in 85% of cases.
    • 4–5 mm clears the tumour in 95% of cases.

  • Large or poorly defined lesions, e.g. morphoeic BCC, require wider excision:

    • 3 mm clears the tumour in 66% of cases.
    • 5 mm clears the tumour in 82% of cases.
    • 13–15 mm clears the tumour in >95% of cases.

  • Up to 2% of BCCs reported as having clear margins will recur.

    • May be due to sampling error during vertical sectioning—so-called ‘bread-loafing’.

      • With this technique, only about 40% of the specimen margin is assessed.

Mohs micrographic surgery


  • An alternative to excision with predetermined margins.
  • Developed by Dr Frederic Mohs (1938) while a medical student at University of Wisconsin–Madison.
  • Gives high cure rates with maximal preservation of normal tissue.
  • Labour intensive; reserved for high-risk lesions in cosmetic areas on the face.
  • Assesses the entire specimen margin intraoperatively:

    1. Obvious tumour mass is removed with no regard for clear margins, leaving a saucer-shaped defect.
    2. Peripheral margins of the defect are marked at 3, 6, 9 and 12 o’clock and the entire margin—both deep and peripheral—is excised with a ≈2 mm margin.
    3. This specimen, which looks like a shallow bowl, is squashed flat and rapidly frozen to allow sectioning parallel to the surface of the skin.
    4. This yields sections containing skin of the periphery and fat of the base of the wound, allowing simultaneous assessment of the entire surgical margin.
    5. Residual tumour is mapped to the orientation markings; further excision is targeted to those zones.
    6. The process is repeated with further excision specimens until clear margins are obtained.

Incompletely excised BCCs


  • Approximately 4–7% of BCCs are incompletely excised.
  • Rate of incomplete excision is higher at inner canthus, alar base and external auditory meatus.
  • Reasons for this are unclear:

    • Invasion can proceed down natural embryonic fusion lines at these sites?
    • BCCs overlying embryonic fusion lines are more likely to be infiltrative?
    • Excision and reconstruction in these areas is more complex?

  • Treatment of incompletely excised BCC is controversial:

    • Excision with intraoperative frozen section analysis of surgical margins.
    • Delayed wound reconstruction until formal pathology report available.

      • Nicknamed ‘slow-Mohs’, although margins are assessed by conventional bread-loafing, not Mohs.

    • Observation of laterally incomplete lesions—only 17% recur.

      • However, incomplete excision of the deep margin has 33% risk of recurrence.

  • Re-excision shows residual tumour in only 55% of cases using Mohs; even less frequently with bread-loafing.
  • Risk of recurrence is highest:

    • Where both lateral and deep margins are involved
    • For excisions of recurrent BCCs
    • For radio-recurrent lesions.

  • Re-excision is particularly recommended in the following situations:

    • Involvement of critical midfacial sites
    • Involvement of deep surgical margin
    • Aggressive histological subtypes
    • Where flaps or skin grafts have been used, which might mask recurrence.

  • UK guidelines recommend excision with wider predetermined margins of 5–10 mm, or Mohs.
  • Radiotherapy is effective in preventing recurrence following incomplete excision.

Other treatment options



  • Destructive methods are best applied to low-risk lesions.

    • Adequacy of excision cannot be assessed by histopathology.

  • Confirming the low-risk nature of a BCC may require biopsy prior to treatment.

Curettage and cautery


  • Common amongst dermatologists.
  • Best suited for small, well-demarcated tumours.
  • Wound left to heal by secondary intention; usually cosmetically acceptable.

Cryotherapy


  • Repeated freeze–thaw cycles cause ice crystals to form in and around tumour cells; causes ischaemia by vascular stasis.
  • Risk of hyper- or hypopigmentation of darker skin tones.

Radiotherapy


  • Cure rates similar to excision; excellent early cosmetic results.
  • Atrophic changes occur over time—unsuitable for treatment of young patients.
  • Following treatment a scab forms that takes several weeks to separate.
  • Useful for elderly patients unsuitable for surgery.

Photodynamic therapy (PDT)


  • A photosensitising chemical, e.g. MAL (methyl aminolevulinate—Metvix®) makes the tumour more susceptible when treated with a light source.
  • Efficacy depends on how deeply MAL penetrates the tumour.
  • Bright light causes MAL to generate oxygen radicals that induce cell death.

CO2 laser


  • Controversial treatment with mixed results; best reserved for superficial BCCs.
  • Combining CO2 laser with PDT is a new approach, with clearance rates comparable to surgery.

Imiquimod (Aldara®)


  • Topical immune response modifier; can be used for superficial BCCs.
  • Binds to Toll-like receptor-7 on macrophages and dendritic cells to induce production of interferon-α, tumour necrosis factor (TNF-α) and various interleukins.
  • This promotes a cell-mediated immune response against the tumour.
  • In addition, imiquimod decreases expression of Bcl-2, leading to tumour apoptosis.
  • Applied for 6 weeks; can cause local and systemic side effects.

5-Fluorouracil (Efudix®)


  • Applied topically to low-risk superficial BCCs.
  • 5-FU is an analogue of thymine; inhibits thymidylate synthetase.
  • This disturbs DNA synthesis, leading to cell death.

Vismodegib (Erivedge®)


  • Systemic inhibitor of the hedgehog signalling pathway.
  • Used for metastatic BCC, or locally advanced disease not amenable to surgery/radiotherapy.

Cutaneous squamous cell carcinoma



  • Malignant tumour of the keratinising cells of the epidermis or its appendages.
  • Second most common skin cancer; 20% of all cutaneous malignancies.
  • Commoner in males—lifetime risk 9–14%; 4–9% in women (US data).

Risk factors



  • Chronic exposure to ultraviolet light or other radiation—sunbeds, outdoor workers.
  • Premalignant lesions—keratin horns, AK, leukoplakia, Bowen’s disease.
  • Smoking—particularly for lip SCC.
  • Immunodeficiency—recipients of organ transplants.
  • Chronic wounds and inflammation—scars, burns, ulcers, psoriasis.
  • Toxins—arsenic.
  • Genetic predisposition—albinism, xeroderma pigmentosum.
  • Viral infection—HPV, herpes simplex.

Histological appearance



  • Dysplastic epidermal keratinocytes invade through basement membrane into dermis.
  • The degree of keratinisation is variable—presence of keratin pearls is characteristic.

Prognostic factors



  • SCCs are prone to local recurrence and metastases.
  • Local recurrence rates are 3–23%, depending on location of the primary.
  • Adverse prognostic factors include:

    • Patient factors
    • Macroscopic features
    • Microscopic features
    • Previous treatment and treatment modality.

Patient factors


  • Immunosuppression.

Macroscopic features

Anatomical site


  • Sites most prone to metastatic spread:

    1. Areas of radiation or thermal injury, chronic draining sinuses, chronic ulcers, chronic inflammation or Bowen’s disease—38%.
    2. Non-sun-exposed sites (e.g. perineum, sacrum, sole of foot)—38%.
    3. Lip—14%.
    4. Ear—9%.
    5. Sun-exposed sites, excluding lip and ear—5% (this is the only category considered ‘low risk’).

Tumour size


  • Tumours >2 cm diameter twice as likely to recur locally and three times as likely to metastasise as smaller tumours.

Microscopic features

Depth of invasion


  • Tumours >4 mm depth (excluding surface layers of keratin) or extending into subcutaneous fat are more likely to recur and metastasise than thinner tumours.
  • Tumours with perineural involvement, lymphatic or vascular invasion more likely to recur and metastasise.

Histological differentiation/Broders grade


  • Broders grade is based on the ratio of differentiated to undifferentiated cells:

    • Grade 1—ratio of 3:1
    • Grade 2—ratio of 1:1
    • Grade 3—ratio of 1:3
    • Grade 4—No tendency towards differentiation.

  • Poorly differentiated tumours (Broders 3 and 4) have poorer prognosis:

    • >2× local recurrence rate and 3× metastatic rate compared to Broders 1 and 2.

Histological subtype


  • Acantholytic, spindle and desmoplastic have poorer prognosis than verrucous subtype.

Previous treatment and treatment modality


  • Primary treatment with Mohs surgery has the lowest rate of recurrence.
  • Locally recurrent disease is a risk factor for metastatic disease.

Related posts:

Default ThumbnailThe Breast and Chest Wall The Trunk and Urogenital System The Lower Limb The Upper Limb General Principles The Head and Neck

Stay updated, free articles. Join our Telegram channel
Tags:
Mar 12, 2016 | Posted by in General Surgery | Comments Off on Skin and Soft Tissue Lesions

Full access? Get Clinical Tree
Get Clinical Tree app for offline access