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OverviewAetiologyPathophysiologyClinical features and red flagsInvestigationsDifferential diagnosisManagementComplicationsMonitoring and follow-upSpecial situationsCommon pitfallsQuestionsSources
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Educational draft · awaiting clinical reviewThe full textbook explains uncertainty but does not replace live national or local guidance, specialist advice, or current prescribing information.

Basal-cell carcinoma

Dermatology · UK scope · Sources checked 27 Aug 2026 · Clinical review pending

RapidFull

Overview

Recognise nodular, superficial, morphoeic and pigmented basal-cell carcinoma, stratify anatomical and histological risk, refer appropriately and explain why apparently slow growth can still cause major local destruction.

Ask about duration, bleeding, crusting, previous treatment, radiation, immune suppression and prior skin cancer. Inspect surface and border with dermoscopy and palpate fixation. Document the relationship to eyelid margin, nose, lip, ear, scalp and named nerves. In darker skin, pearliness and telangiectasia may be less visually prominent while pigmentation or ulceration dominates.

Risk stratification combines site, size, definition, primary versus recurrent status, immune state and histological subtype. The facial H-zone, ears, lips, hands, feet and genital skin are high-consequence locations. A small ill-defined morphoeic tumour near the eye can require more expertise than a larger sharply defined superficial trunk lesion.

Treatment must follow a secure diagnosis. Standard excision provides histology and margins; Mohs examines staged margins while conserving tissue. Selected superficial low-risk lesions can use non-surgical treatment, but these lack complete histological margin assessment and often have lower cure rates. Advanced unresectable BCC may receive specialist hedgehog-pathway or immunotherapy treatment.

Key points

  • Nodular BCC is a pearly or translucent papule with arborising vessels, rolled edge and possible central ulceration.
  • Superficial BCC is a thin pink-red, brown or subtly pigmented scaly plaque, often on trunk, and can resemble eczema.
  • Morphoeic BCC appears scar-like, firm, pale or yellow-white and poorly defined; its subclinical extension makes it high risk.
  • Pigmented BCC occurs in every skin tone and can mimic melanoma; refer diagnostic uncertainty without destructive treatment.
  • Most low-risk BCCs are referred routinely, but NICE advises urgent referral when delay could materially affect outcome because of site or size.
  • Surgical excision is standard for many tumours; Mohs surgery is considered where tissue conservation and complete margin control matter.
  • Topical imiquimod, topical 5-fluorouracil, curettage, cryotherapy or photodynamic therapy suit selected low-risk superficial lesions after diagnosis.
  • Metastasis is rare, but local invasion can be severe; new pain, numbness, weakness or fixation is not compatible with casual routine follow-up.

Aetiology

01

Cumulative ultraviolet exposure

Long-term ultraviolet radiation causes DNA injury in basal keratinocyte lineage, particularly on intermittently and chronically exposed head and neck skin.

02

Phenotypic susceptibility

Lighter skin, tendency to burn, older age and previous keratinocyte cancer increase risk, but BCC can occur in every skin tone.

03

Genetic pathway activation

Hedgehog-pathway dysregulation drives most tumours and is inherited in basal-cell naevus syndrome or acquired through sporadic cellular mutations.

04

Additional carcinogenic exposure

Ionising radiation, arsenic, chronic scars and immune suppression contribute to selected cases and can alter presentation or multiplicity.

Pathophysiology

  1. 1
    Indolent local invasion

    Basaloid tumour nests grow slowly through dermis with stromal interaction, producing a pearly edge and progressive local tissue destruction.

  2. 2
    Ulceration

    Central tumour breakdown creates a recurrently bleeding or crusted rodent ulcer while the raised active border advances.

  3. 3
    Infiltrative growth

    Morphoeic, micronodular and infiltrative subtypes extend beyond visible boundaries in narrow strands and recur more readily after incomplete treatment.

  4. 4
    Rare dissemination

    Metastasis is exceptionally uncommon, but neglected or aggressive tumours can invade cartilage, bone, orbit, nerves and other critical local structures.

Clinical features and red flags

Pearly rolled edge

A translucent raised border with branching vessels surrounds a papule or ulcer and is classic for nodular BCC.

Superficial scaly plaque

A slowly enlarging thin plaque has a fine thread-like edge and may be pink, red or brown.

Morphoeic scar-like plaqueRed flag

An indurated ivory or yellow-white poorly defined plaque can extend well beyond what is visible.

Pigmented BCC

Brown, black or blue-grey pigment within a shiny papule can resemble melanoma and requires expert dermoscopic distinction.

Perineural warningRed flag

New pain, paraesthesia, numbness or weakness near a tumour suggests nerve invasion and requires urgent escalation.

Red flags requiring action

  • Rapid change, deep fixation, cranial-nerve symptoms, recurrent tumour, ill-defined morphoeic plaque, large neglected ulcer or periocular, nasal, lip or ear disease threatens critical structures and requires urgent specialist assessment.

Investigations

  1. 01
    DermoscopyFirst step
    Why
    Identify arborising vessels, shiny white structures, ulceration, leaf-like areas and blue-grey nests.
    Interpretation and limitations
    Patterns support subtype but melanoma uncertainty remains a reason for complete diagnostic assessment.
  2. 02
    Incisional, punch or excision biopsy
    Why
    Confirm diagnosis and growth pattern before risk-appropriate treatment.
    Interpretation and limitations
    Choose a representative active area and adequate depth; a superficial sample may miss infiltrative components.
  3. 03
    Histological margin assessment
    Why
    Determine complete removal and aggressive subtype after excision.
    Interpretation and limitations
    An involved or narrowly clear margin is interpreted with site, subtype and recurrence risk at multidisciplinary review.
  4. 04
    Imaging for advanced disease
    Why
    Assess orbit, bone, cartilage or perineural extension when clinical findings suggest deep invasion.
    Interpretation and limitations
    Routine imaging is unnecessary for ordinary low-risk BCC; targeted MRI or CT follows anatomical concern.

Differential diagnosis

01

Squamous-cell carcinoma

A faster-growing tender keratotic or ulcerated lesion, especially on lip or ear, raises SCC concern and requires urgent referral.

02

Melanoma

Pigmented BCC can mimic melanoma; evolution, asymmetry and melanoma dermoscopy mandate intact specialist assessment rather than presumptive destruction.

03

Sebaceous hyperplasia

Multiple soft yellow-pink facial papules with central dell and crown vessels are benign, but a solitary uncertain lesion needs dermoscopy.

04

Actinic keratosis or Bowen disease

Rough macules and well-demarcated scaly plaques lack the classic pearly rolled border, though histology may be needed.

Management

01Low-risk suspected BCCObtain diagnosis and definitive careFirst stepDefinitiveA well-defined primary lesion is away from high-risk sites and lacks aggressive features.+
  1. 1Document site, size, border and dermoscopy and refer through the local routine BCC pathway when clinically appropriate.
  2. 2Use standard excision with histology for many lesions or a selected non-surgical option for confirmed superficial low-risk disease.
  3. 3Review pathology, healing and recurrence advice and support ultraviolet protection and whole-skin awareness.
02High-risk BCCProtect structures and marginsTumour is recurrent, ill-defined, morphoeic, large, immunosuppression-associated or on a critical site.+
  1. 1Refer urgently when delay affects outcome and provide prior pathology, procedures, photographs and nerve symptoms.
  2. 2Plan Mohs or specialist excision and reconstruction with imaging for suspected deep or perineural spread.

Complications

01

Critical local destruction

Growth on eyelid, nose, ear or lip can invade cartilage, orbit and bone and require disfiguring reconstruction.

02

Perineural invasion

Rare nerve involvement causes pain, numbness or weakness and signals aggressive disease needing multidisciplinary imaging and treatment.

03

Recurrence

Ill-defined, infiltrative, previously treated or incompletely excised tumours recur more often and may become harder to clear.

04

Multiple primary tumours

One confirmed BCC predicts additional keratinocyte cancers, making ultraviolet prevention, self-awareness and risk-based whole-skin surveillance important.

Monitoring and follow-up

  • Check pathology subtype and margins after excision and ensure further management is explicitly documented.
  • After non-surgical treatment, confirm clinical clearance rather than assuming inflammation equals cure and biopsy persistent change.
  • Review scar, surrounding skin and neurological symptoms for recurrence, especially after high-risk or incomplete treatment.
  • Teach self-awareness for new non-healing, bleeding or pearly lesions and reinforce practical ultraviolet protection.
  • Patients with multiple tumours, syndromic disease or immune suppression need individual specialist surveillance intervals.

Special situations

Rarely metastatic is not harmless

Slow local invasion near eye, nose or ear can destroy function and demand complex reconstruction.

Morphoeic exceeds its outline

Infiltrative strands often extend beyond the visible scar-like plaque, favouring margin-controlled surgery.

Pigment does not equal melanoma

BCC may contain abundant pigment, but uncertainty between them still requires tissue-preserving cancer assessment.

Inflammation is not clearance

A vigorous imiquimod reaction indicates immune activation but follow-up must still establish tumour resolution.

Common pitfalls

  1. 01

    Calling a recurrently bleeding nasal papule a harmless spot because it has grown slowly.

  2. 02

    Using topical treatment on an unbiopsied morphoeic or nodular lesion.

  3. 03

    Assuming metastasis rarity makes delay safe at eyelid, nose or ear sites.

  4. 04

    Ignoring numbness beside a recurrent lesion and missing perineural spread.

  5. 05

    Treating a pigmented BCC-like lesion destructively before melanoma has been excluded.

Practice

Two practice questions

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Question 1 of 2
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DermatologyOriginal SBA

Pearly ulcerated nasal papule

A slowly enlarging nasal papule has a translucent rolled edge, arborising vessels and recurrent central crusting. What is the most likely diagnosis?

Choose one answer, then submit
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Sources and review status3 sources · checked 27 Aug 2026 · clinical review pending+
Sources

Sources and review status

National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 27 Aug 2026; clinical approval remains outstanding.

  • British Association of Dermatologists basal-cell carcinomaMorphology, subtypes, treatment and recurrence.
  • NICE NG12 suspected skin cancer referralRoutine versus urgent BCC referral.
  • Aldara 5% cream SmPCLicensed superficial BCC regimen and cautions.

Editorial contact: Doctor’s Passport editorial team. Source-check date is separate from clinical approval. Report a content problem · Content changes

Authoring stateComplete draftClinical stateAwaiting reviewJurisdictionUnited Kingdom
  • 3Use multidisciplinary treatment for unresectable or advanced disease and monitor functional as well as oncological outcomes.
    • 03Possible recurrenceBiopsy the scar changeA treated site develops persistent ulceration, induration, pearly papule, pain or sensory change.+
    1. 1Compare with prior subtype and margins and examine regional anatomy and nerves.
    2. 2Biopsy an active representative area and image deep or neural symptoms rather than attributing change to scar alone.
    3. 3Refer recurrent disease for margin-controlled treatment and longer risk-based surveillance.
    Key medicines and prescribing safety1 treatment · regimens, roles and cautions+
    A tissue-sparing non-surgical option for confirmed superficial low-risk BCC where surgery is appropriate to avoid or unsuitable.

    Imiquimod 5% cream

    For selected small superficial BCC, apply five times weekly for six weeks according to the licensed product and specialist-confirmed plan.

    Expected inflammation can be marked; avoid eyes and mucosa, review non-response, pregnancy and immune status, and do not use for nodular or high-risk disease without specialist direction.