Dermatology · PANCE / PANRE

Basal Cell Carcinoma

Written & clinically reviewed by Ryan Busch, PA-C · Updated August 2026 · Report an error

Most common human cancer; slow-growing locally invasive tumor of basal keratinocytes driven by UV-induced PTCH/Hedgehog mutations.

Also known as: BCC, basal cell carcinoma, rodent ulcer, nodular BCC, morpheaform BCC

Overview

The most common cutaneous malignancy, arising from basal keratinocytes of the epidermis and hair follicle. Slow-growing, locally invasive, and rarely metastatic.

Epidemiology

Most common cancer in humans worldwide. ~4 million US cases annually. Lifetime risk ~30% in fair-skinned individuals. Male > female (2:1). Median age at diagnosis ~70, but incidence rising in younger adults.

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Question 1DermatologyEasy
A 72-year-old man has a pearly papule with telangiectasias and rolled borders on his nose that bleeds intermittently and has been present for 2 years. Which of the following is the most likely diagnosis?
  • ASebaceous cyst
  • BMelanoma
  • CBasal cell carcinoma
  • DSquamous cell carcinoma
Reveal answer & full explanation
Correct answer: C — Basal cell carcinoma
  • ASebaceous cyst
  • BMelanoma
  • CBasal cell carcinoma✓
  • DSquamous cell carcinoma

Why Basal cell carcinoma is correct

  • A pearly papule with overlying telangiectasias and rolled (pearlescent) borders on a sun-exposed site is the classic morphology of basal cell carcinoma
  • It is the most common skin cancer; the head and neck account for 70-80% of cases, and the nose is a high-frequency site
  • Slow growth over 2 years with intermittent bleeding and ulceration fits its locally invasive but low-metastatic behavior
  • Diagnosis is confirmed by shave or punch biopsy; Mohs micrographic surgery is preferred for the central face given the high cure rate and tissue sparing

Why the others are wrong

  • Sebaceous cyst — a mobile, flesh-colored subcutaneous nodule with a central punctum, not a pearly telangiectatic papule; the premature-closure pick for any chronic facial bump
  • Melanoma — a pigmented, asymmetric lesion with border and color variation, not a translucent pearly papule; anchoring on "skin cancer" without matching the morphology
  • Squamous cell carcinoma — a scaly, hyperkeratotic or ulcerated nodule on sun-exposed skin; the confused-with-BCC distractor, but it lacks the pearly rolled border and telangiectasias
Question 2DermatologyMedium
A 68-year-old man with a 40 pack-year history presents with a firm, pearly, rolled-border papule with central telangiectasias and ulceration on his nose. The lesion has been slowly growing for 18 months. Which is the most appropriate treatment?
  • AMohs micrographic surgery
  • BTopical imiquimod cream
  • CCryotherapy
  • DElectrodesiccation and curettage
Reveal answer & full explanation
Correct answer: A — Mohs micrographic surgery
  • AMohs micrographic surgery✓
  • BTopical imiquimod cream
  • CCryotherapy
  • DElectrodesiccation and curettage

Why Mohs micrographic surgery is correct

  • Basal cell carcinoma (BCC) is the most common skin cancer; it has low metastatic risk but is locally invasive
  • A pearly papule with rolled borders, telangiectasias, and central ulceration on sun-exposed skin of an elderly patient is classic nodular BCC
  • Mohs micrographic surgery is the preferred treatment for BCC on the face (nose, eyelid, ears) because it achieves the highest cure rate with maximal tissue conservation

Why the others are wrong

  • B) Topical imiquimod cream — topical imiquimod is for superficial BCC on non-critical sites, not high-risk facial nodular BCC
  • C) Cryotherapy — an option for small, well-defined, low-risk lesions on non-facial sites; inappropriate for a high-risk facial nodular BCC
  • D) Electrodesiccation and curettage — also an option for small, well-defined, low-risk lesions on non-facial sites; inappropriate for a high-risk facial nodular BCC
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Risk factors

  • Chronic and intermittent UV exposure (UVB > UVA); cumulative lifetime exposure most important
  • Fair skin (Fitzpatrick I-II), light hair and eyes
  • Ionizing radiation (childhood radiation therapy)
  • Immunosuppression (organ transplant — 10x risk; HIV; chronic immunosuppressants)
  • Arsenic exposure (drinking water in some regions; multiple BCCs and superficial palmar/plantar keratoses)
  • Genetic syndromes: basal cell nevus (Gorlin) syndrome — PTCH1 mutation; xeroderma pigmentosum; Bazex-Dupré-Christol; Rombo syndrome
  • Personal history of skin cancer (40% develop second BCC within 5 years)

Pathophysiology

UV radiation induces mutations in PTCH1 (most common, ~70%), SMO, and SUFU components of the Hedgehog signaling pathway → constitutive Hedgehog activation → GLI transcription factor activation → uncontrolled basaloid proliferation. p53 mutations also common. Slow growth and intact stromal interactions limit metastatic potential (<0.05%).

Clinical presentation

Symptoms

  • Often asymptomatic; patient notices 'pimple' or 'sore that won't heal' for months to years
  • Occasional bleeding with minor trauma; rarely painful unless ulcerated/infected

Signs / physical exam

  • Nodular BCC (most common, ~60%): pearly translucent papule or nodule with rolled border, arborizing telangiectasias, and central depression or ulceration ('rodent ulcer')
  • Superficial BCC (~30%): erythematous scaly slightly elevated patch with thread-like rolled border; trunk/extremities; can mimic eczema/psoriasis
  • Pigmented BCC: nodular BCC with brown/blue-gray pigment; common in skin of color
  • Morpheaform (sclerosing/infiltrative) BCC: ill-defined indurated white-yellow scar-like plaque; high recurrence; subclinical extension
  • Basosquamous: aggressive variant with mixed histology
  • Distribution: 80% on head/neck (especially nose, ears, eyelids, lips); less commonly trunk and extremities

Classic findings

Pearly translucent nodule with rolled border, telangiectasias, and central ulcer on a sun-exposed area of an older fair-skinned adult.

Differential diagnosis

  • Squamous cell carcinoma — Hyperkeratotic, scaly, ulcerated, more rapid growth; sun-damaged background
  • Melanoma (amelanotic / nodular) — Pink or pigmented nodule; biopsy mandatory
  • Sebaceous hyperplasia — Yellow-pink lobulated papule with central umbilication; benign
  • Intradermal melanocytic nevus — Soft skin-colored papule, stable over years
  • Molluscum contagiosum — Smooth umbilicated papules, multiple, children/immunocompromised
  • Trichoepithelioma / fibrofolliculoma — Familial multiple small papules on face; biopsy
  • Microcystic adnexal carcinoma — Indurated yellowish-pink plaque, slow growth on face; deeply invasive
  • Bowen disease (SCC in situ) — Erythematous scaly plaque, slow growth

Diagnostic workup

Diagnostic criteria

Histopathologic confirmation of basaloid tumor cells in palisading nests with retraction artifact and myxoid stroma.

Labs

  • Tissue diagnosis required — skin biopsy (shave or punch)
  • Histopathology subtype determines management (nodular, superficial, morpheaform/infiltrative, basosquamous, micronodular)

Imaging

  • CT/MRI only for advanced or recurrent tumors with suspected perineural invasion or deep tissue involvement
  • Routine imaging not indicated for typical primary BCC

Diagnostic algorithm

SubtypeAppearancePreferred Treatment
Nodular (60%)Pearly papule, rolled border, telangiectasias, central ulcerSurgical excision 4 mm margin; Mohs if H-zone
Superficial (30%)Erythematous scaly patch with thread-like rolled borderImiquimod, 5-FU, ED&C, or excision
PigmentedNodular BCC with brown/blue-gray pigmentExcision; Mohs if H-zone
Morpheaform / infiltrativeIll-defined scar-like indurated plaqueMohs preferred — subclinical extension common
Basosquamous (aggressive)Variable; mixed BCC + SCC histologyMohs ± radiation; consider systemic for advanced
Locally advanced / metastaticDeep invasion or unresectableVismodegib / sonidegib; cemiplimab if HPi-resistant
Basal cell carcinoma subtypes and preferred treatment.

Treatment

First-line

  • Surgical excision with 4 mm margins for low-risk primary BCC (cure rate ~95%)
  • Mohs micrographic surgery (preferred for high-risk BCC): face (especially H-zone — central face, periocular, periauricular, perinasal), morpheaform/infiltrative subtypes, recurrent tumors, large tumors (>2 cm), positive margins after standard excision — cure rate ~99% for primary, ~95% for recurrent
  • Electrodessication and curettage (ED&C) for low-risk superficial or small nodular BCC on trunk/extremities (NOT on terminal hair-bearing skin or face — high recurrence)
  • Topical therapy for superficial BCC: imiquimod 5% cream 5x/week × 6 weeks OR 5-fluorouracil 5% cream BID × 3-6 weeks — cure rates 70-90%
  • Cryotherapy with liquid nitrogen for superficial BCC in selected patients
  • Photodynamic therapy for superficial BCC (cosmetic advantage)
  • Radiation therapy for non-surgical candidates or as adjuvant

Locally advanced / metastatic BCC

  • Hedgehog pathway inhibitors: vismodegib 150 mg daily, sonidegib 200 mg daily — for laBCC or mBCC not amenable to surgery/radiation
  • Adverse effects: muscle spasms, dysgeusia, alopecia, weight loss, teratogenicity (strict contraception)
  • Cemiplimab (anti-PD-1) — FDA-approved for laBCC after Hedgehog inhibitor failure

Basal cell nevus (Gorlin) syndrome

  • Multidisciplinary surveillance starting in childhood
  • Limit UV and radiation exposure (avoid CT when possible)
  • Vismodegib for tumor burden reduction
  • Genetic counseling for family members

Second-line / adjunct

  • Annual to biannual total body skin examination — 40% develop second BCC within 5 years
  • Sun protection counseling: broad-spectrum SPF ≥30 daily, sun-protective clothing, hat, sunglasses, shade
  • Vitamin D supplementation as appropriate (avoid recommending sun exposure for vitamin D)

Complications

  • Local tissue destruction — 'rodent ulcer' can erode cartilage, bone, eye, brain in neglected cases
  • Cosmetic/functional disfigurement, especially on face
  • Recurrence (lifetime ~50% develop another skin cancer)
  • Rare metastasis (<0.05%) — usually basosquamous or morpheaform subtypes
  • Hedgehog inhibitor adverse effects and resistance over time

PANCE pearls

  • Pearly translucent papule + rolled border + arborizing telangiectasias + central ulcer = nodular BCC.
  • Morpheaform BCC looks like a scar without history of injury — biopsy any new 'scar' on sun-damaged skin.
  • ED&C should NEVER be used on the face or hair-bearing scalp — high recurrence.
  • Imiquimod and 5-FU are excellent options for superficial BCC on trunk/extremities, but expect significant inflammation during treatment.
  • Hedgehog pathway inhibitors (vismodegib, sonidegib) revolutionized therapy for advanced BCC — particularly impactful in Gorlin syndrome.

References

  • NCCN 2024 — NCCN Clinical Practice Guidelines in Oncology — Basal Cell Skin Cancer (Version 1.2024)
  • AAD 2018 — Guidelines of Care for the Management of Basal Cell Carcinoma (Kim et al., J Am Acad Dermatol 2018)
  • USPSTF 2023 — USPSTF Recommendation: Screening for Skin Cancer (JAMA 2023)

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Commonly confused with

vs Squamous Cell Carcinomavs Melanoma

Related Dermatology diagnoses

Acne VulgarisRosaceaAtopic Dermatitis (Eczema)Allergic and Irritant Contact DermatitisSeborrheic DermatitisPsoriasisLichen PlanusPityriasis RoseaTinea Infections (corporis, capitis, pedis, cruris, versicolor)Cutaneous CandidiasisScabiesPediculosisImpetigoHerpes Zoster (Shingles)

Differentials & related conditions

Squamous Cell CarcinomaMelanomaMolluscum Contagiosum

Educational use only. This outline is a study aid for PA students and is not medical advice or a substitute for clinical judgment. FirstPassPA is an independent study tool and is not affiliated with, endorsed by, or sponsored by NCCPA or PAEA. PANCE® and PANRE® are registered trademarks of the National Commission on Certification of Physician Assistants; End of Rotation™ is a program of the Physician Assistant Education Association.