- 1 Background
- 2 Overview of evidence (non-systematic literature review)
- 3 Superficial basal cell carcinoma
- 4 Nodular basal cell carcinoma
- 5 Sclerosing basal cell carcinoma
- 6 Influence of subtype on prognosis of basal cell carcinoma
- 7 References
There are three common growth patterns of basal cell carcinoma (BCC) that have a distinctive clinical presentation:
- superficial multifocal
- sclerosingscar-like (morphoeic) (morphoeic).
Numerous histological subtypes of BCC have been described, but most are uncommon and do not have distinctive clinical presentations. Some may be multiple and difficult to diagnose.
Superimposed on any of these growth patterns may be ulceration or pigmentation. Although ulceration and pigmentation lead to a distinctive clinical appearance, these features do not correspond to a specific histological growth pattern and are therefore no longer considered to represent separate subtypes of BCC.
Immunosuppression for organ transplantation predisposes to BCC (see: Organ transplantation and other conditions associated with prolonged immunosuppression). Left untreated, over years, BCCs can cause significant morbidity for the patient.
Overview of evidence (non-systematic literature review)
Dermoscopy (surface microscopy, epiluminescence microscopy, dermatoscopy) is a technique that is established as a significant aid in the diagnosis of pigmented lesions, particularly melanoma. More recently, it has been shown to have benefit in the diagnosis of BCC and other non-pigmented lesions, such as cutaneous squamous cell carcinoma (cSCC) in situ (also known as Bowen’s diseasecSCC in situ (also known as intra-epidermal SCC) or intra-epidermal squamous cell carcinoma). Dermoscopy is also useful in distinguishing between melanoma and pigmented BCC.
Accuracy of clinical diagnosis of basal cell carcinoma
The diagnostic accuracy of clinical examination by experienced dermatologists for the diagnosis of BCC among randomly selected samples from the general community is around 59% to 65%. This is somewhat lower than would be expected in clinical practice because of the much lower prevalence of skin cancers in the community, compared with the clinical setting.
No data are available regarding the diagnostic accuracy of clinicians in Australia, but in a clinical practice setting in the USA a diagnostic accuracy of 70% has been reported for university-based dermatologists. These observations indicate that, in spite of the frequency of BCC and in spite of high levels of clinical experience, diagnosis may be difficult on occasion.
Superficial basal cell carcinoma
Superficial BCC is a subtype of BCC that commonly occurs in Australians. Superficial BCCs generally occur on the trunk or limbs. In younger people they occur more often than other growth patterns.
Superficial BCC usually presents as a reasonably well-defined, erythematous, scaling or slightly shiny macular lesion. The degree of erythema present may vary and will be increased by stretching or rubbing the lesion. Stretching the lesion will highlight the shiny surface and may reveal, to the naked eye, a peripheral thread-like pearly rim or islands of pearliness distributed through the lesion.
A minority of superficial BCCs are symptomatic, with itching being the most common symptom. Although these lesions are readily eroded by minor trauma, a history of ulceration or bleeding is uncommon.
Exposure to sunlight is the most common cause of superficial BCC. Multiple superficial BCCs may also occur in the context of arsenic intoxication. Other stigmata of arsenic intoxication include punctate palmoplantar keratoderma, scattered macular hypopigmentation and longitudinal pigmented bands or horizontal hyperpigmented stripes in fingernails and toenails.
Many superficial BCCs will progressively enlarge over months to years and if left, may reach 5–10cm in diameter. Some may be relatively stable and a few will regress. With time, areas of nodular and even sclerosingscar-like (morphoeic) growth pattern may supervene within the original superficial BCC.
Superficial BCC should be distinguished from:
- actinic (solar) keratosis
- Bowenoid keratosisactinic keratosis showing full-thickness atypia without dermal invasion
- Bowen's disease
- amelanotic melanoma.
As the management of superficial BCC may differ from that of these other tumours, a biopsy to obtain definitive pathology should be undertaken prior to definitive treatment. The appearance may suggest an inflammatory dermatosis such as eczema or psoriasis. However, the clinical history of superficial BCC is one of inexorable enlargement over months or years while inflammatory lesions are generally more transient. Dermoscopy may be a helpful tool in diagnosis of these lesions.Back to top
Nodular basal cell carcinomaNodular BCCs are more often found on the head and neck in people who are somewhat older on average than those with superficial BCC.
Nodular BCC typically presents as a shiny, translucent (pearly), telangiectatic papule or nodule. The translucent or pearly appearance is more obvious if the clinician stretches the skin during examination. As the lesion enlarges the dilated capillaries may be seen coursing across the surface of the lesion. These are often radially arranged.
Ulceration may occur with time and may lead to central umbilication of the lesion with a more raised rolled border. Islands of pigmentation may become clinically visible and the lesion may become darkly pigmented, suggesting melanoma. Like superficial BCC, these may be associated with sensory symptoms (only in a minority of cases) but, unlike superficial BCC, nodular lesions often ulcerate and bleed.
Nodular BCCs need to be differentiated from squamous cell carcinoma, amelanotic nodular melanoma and, rarely, Merkel cell carcinoma.
The differential diagnosis also includes various benign lesions.
Nodular BCCs may progressively enlarge, invade locally and ulcerate over a period of months to years.
Sclerosingscar-like (morphoeic) basal cell carcinoma
Sclerosingscar-like (morphoeic) (morphoeic) BCC has a similar body-site distribution to that of nodular BCC. Sclerosingscar-like (morphoeic) BCCs are usually of long standing and tend to be deeply invasive.
These lesions have a sclerosingscar-like (morphoeic) growth pattern with fibrosis surrounding areas of BCC. Basal cell carcinomas that are predominantly sclerosingscar-like (morphoeic) have the appearance of a pale scar.
Palpation usually reveals firm induration, which may extend more widely and deeply than is evident on inspection. Sclerosingscar-like (morphoeic) changes will frequently supervene in longstanding nodular BCCs and these lesions may retain some clinical features of nodular BCC.
Sclerosingscar-like (morphoeic) BCCs are frequently asymptomatic. Those with nodular elements may show all the same symptoms as nodular BCCs.
Sclerosingscar-like (morphoeic) BCCs may remain undetected by doctor and patient for many years and may slowly enlarge and deepen to reach a large size before being treated.
The major differential diagnosis of sclerosingscar-like (morphoeic) BCC is scar tissue. Biopsy is necessary to establish the diagnosis.
Recurrence in sclerosingscar-like (morphoeic) BCCs can be common, and therefore requires regular monitoring. Some recurrence may be due to local incomplete excision, with satellite islands of BCC either having not been visible at the time of surgery, or being distant from the primary lesion, particularly in those with certain genetic syndromes such as Gorlin’s syndrome(naevoid BCC syndrome) an autosomal dominant syndrome characterised by multiple BCCs (naevoid BCC syndrome) or those with immunosuppression.
Sclerosingscar-like (morphoeic) lesions should be reviewed more frequently and may benefit from specialist review.
Influence of subtype on prognosis of basal cell carcinoma
Certain BCC subtypes (Table 1) are associated with a poor prognosis.
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