Skin Cancer: ABCDE Melanoma Triage, Mohs Pathways & Pembrolizumab Toxicity Vigil

Skin cancer encompasses malignant neoplasms arising chiefly from basal keratinocytes (BCC), squamous keratinocytes (cSCC), or melanocytes (melanoma). Keratinocyte carcinomas typically begin as sun-damaged skin clones that expand locally and only occasionally metastasise unless high-risk histology or host factors intervene. Melanoma behaves more aggressively early in its natural history once invasive thresholds are crossed, frequently routing disease through lymphatics or bloodstream despite a relatively small visible primary lesion.

Pathophysiology converges on ultraviolet radiation–induced DNA injury, immunosurveillance decline, and—for melanoma—oncogenic signalling pathways that permit vertical growth and distant seeding. Immunosuppressed transplant recipients experience disproportionate cSCC biology; inherited syndromes such as xeroderma pigmentosum or basal cell naevus syndrome shift baseline risk dramatically even without occupational UV.

Nurses anchor multidisciplinary flow by translating lesion histories into standardised documentation, capturing measuring tapes or lesion sketches when permitted, ensuring timely suspected-cancer referrals instead of silent dermatology queues, and aligning patient expectations with staged biopsy-to-definitive treatment sequencing rather than same-day cure myths.

Staging intent differs by subtype. BCC rarely demands nodal imaging unless neglected giant tumours or infiltrative variants prompt concern. cSCC uses AJCC TNM features plus histologic high-grade patterns (perineural invasion, poor differentiation, depth beyond defined cut-offs) to stratify locoregional metastasis risk and adjuvant radiation discussions. Melanoma hinges on Breslow thickness, ulceration, mitotic rate where recorded, nodal burden, lactate dehydrogenase in advanced disease, and distant metastasis mapping—sentinel lymph node biopsy sits inside guideline-selected intermediate-thickness windows rather than universal practice.

BCC often surfaces as a pearly papule with telangiectasia, a recurrent erosion, or a scar-like plaque when infiltrative. cSCC frequently presents as a tender keratotic nodule, ulcer with heaped violaceous edges, or lesion arising within chronic scars and burns. Melanoma advertises asymmetry, irregular borders, colour variegation, evolving diameter or symptoms, and occasionally amelanotic pink nodules that fool purely pigment-based screening.

• Typical cues: slowly enlarging plaques, easy bleeding after minor friction, localized lymph tenderness when infection coexists.
• Atypical cues: diffuse hyperkeratosis masking tumour base, bilateral itching mistaken for eczema flares, ocular or mucosal pigment changes reported verbally without nurse inspection opportunity.
• Functional clues: facial lesions interfering with eyelid closure, nasal obstruction from neglected nasal wing tumours, scalp lesions avoided by hairdressers until advanced.

Any narrative matching changing mole semantics—or a firm lump under the skin near known sun damage—belongs in fast-track documentation with dated lesion outline drawings where policy permits.

Ultraviolet radiation remains the dominant environmental carcinogen for keratinocyte cancers and a major melanoma contributor, amplified by intermittent intense burns and indoor tanning devices. Phenotype mixes fair skin, light eyes, poor tanning capacity, and childhood blistering burns into higher curves across all subtypes.

• Non-modifiable: age accumulation of mutations, male predominance in some populations, prior cancer fields.
• Modifiable: outdoor occupational exposure without sleeves, phototherapy without dermatology oversight, continued sunbed use.
• Medical amplifiers: chronic lymphocyte suppression after transplant, lupus biology plus photosensitising drugs, radiation dermatitis fields harbouring second malignancies.

Sunburn episodes provide teachable moments—pair burn care advice with explicit referral prompts when blistering injuries coexist with numerous atypical naevi.

Clinical evaluation blends lesion natural history, regional lymph node survey, and dermatoscopic eligibility where trained clinicians deploy handheld instruments. Photography scales lesions objectively across visits when smartphones integrate securely with electronic records.

Biopsy discipline

Suspicious pigment lesions generally require full-thickness sampling via excision or appropriately placed punch so vertical depth can be measured—superficial shave biopsies risk underestimating melanoma thickness unless lesion morphology is exceedingly low suspicion and pathway-approved. Keratinocyte lesions may be shaved when purely diagnostic before definitive therapy planning, yet coordinate with pathology turnaround targets from suspected-cancer standards.

Laboratory & microbiology

Infected ulcer mimic obtains skin culture prior to antibiotics when purulence dominates; malignancy remains on the differential until sampling proves reactive inflammation only.

Imaging

Cross-sectional staging escalates with nodal positivity, neurologic symptoms, bulky locoregional disease, or planning oligometastatic therapy—precise modality sequences belong to oncology/radiology protocols rather than ad hoc ward ordering.

• Inflammatory mimics: plaque psoriasis flares, hypertrophic eczema, rosacea fulminans—distribution and steroid responses differ but biopsy resolves stalemate.
• Infectious mimics: fungal plaques, cutaneous horns atop benign keratoses—KOH or biopsy when morphology straddles categories.
• Vascular lesions: pyogenic granuloma bleeding profusely yet sometimes coexisting with carcinoma—excision sends unified specimen.
• Benign melanocytic naevi—stable symmetric lesions versus evolving outliers documented through total-body photography programmes.

Keratinocyte disease

Superficial or low-risk lesions may yield to curettage and cautery, topical photodynamic therapy, laser-ablative protocols within dermatology, or skin-directed field agents—fluorouracil remains relevant where formulary pathways support extensive field carcinogenesis. Surgical excision with margin control (including Mohs micrographic surgery for cosmetically sensitive sites) anchors most high-risk BCC/cSCC plans; adjuvant radiotherapy appears when margins or perineural invasion remain threatening.

Melanoma & advanced disease

Wide local excision plus selective sentinel node staging transitions into adjuvant pembrolizumab or combination immunotherapy for high-risk resected disease per tumour-board consensus. Unresectable locoregional or metastatic melanoma layers BRAF/MEK-targeted options when mutations arise. Locally advanced basal cell carcinoma accesses smoothened inhibitors under oncodermatology stewardship.

Supportive modalities

Radiotherapy relieves bleeding fungating masses, bone pain from metastases, or nodal beds unsuitable for salvage surgery; electrochemotherapy occasionally surfaces for cutaneous metastasis symptom control within specialist centres.

• Referral latency audits: track suspected-cancer countdown deadlines from primary referral letter to first definitive treatment touchpoint.
• Biopsy site nursing: maintain sterile technique, photograph plaster orientation, warn patients about superficial bleeding during anticoagulation—without advising medication changes unless prescribed.
• Teach explicit immune-oncology symptom thresholds at every infusion education touch—diarrhoea frequency, breathlessness, oliguria, confusion.
• Coordinate dressing clinics when fungating wounds soils clothing; involve tissue viability teams early.
• Repeat structured skin assessment after systemic steroids or antibiotics that might transiently beautify erythema yet mask progression.

• Local destruction: cartilage invasion, orbital penetration, skull-base erosion when lesions procrastinate.
• Regional spread: nodal metastasis requiring neck dissection or adjuvant radiation in cSCC and melanoma contexts.
• Distant metastasis: lung, liver, bone, brain deposits depending on subtype—neurologic surveillance integrates into melanoma programmes.
• Treatment toxicity: surgical flap necrosis, radiation dermatitis, hedgehog-pathway inhibitor muscle cramps, immunotherapy endocrinopathies.

Clinician-facing prevention emphasises structured UV minimisation for high-risk cohorts, occupational protective clothing enforcement, chemoprevention discussions for extreme photodamage under dermatology, and HPV vaccination relevance where applicable for certain mucosal SCC contexts per national schedules—not anecdotal sunscreen marketing.

Secondary prevention hinges on early detection programmes for transplant recipients, survivors of prior skin cancer, and individuals with giant congenital naevi or familial melanoma pedigrees—photographic surveillance intervals follow specialist protocols.

Localized BCC carries excellent prognosis after complete excision; neglected tumours threaten tissue integrity more than distant organs. cSCC prognosis stratifies sharply once nodal metastasis or poorly differentiated deep invasion appears—five-year outcomes swing with stage but remain generally worse than basal disease. Melanoma prognosis maps tightly to AJCC stage—with contemporary immunotherapy improving metastatic curves yet demanding vigilant toxicity trade-offs.

Communication friction

Patients often minimise lesions as “just sun spots.” Replace judgement with dated lesion drawings and objective measurements so sceptical relatives witness change.

Technology aids

Smartphone mirrors aid self-check teaching yet introduce lighting bias—standardise photography instructions when clinics distribute patient-facing guides.

Documentation prompts

Capture transplant status, prior radiotherapy fields, occupational arsenic or PAH exposures—often buried in social histories yet decisive for risk counselling.

Nursing-priority lens (NCSBN Clinical Judgment Measurement Model): recognise cues → analyse cues → prioritise hypotheses → generate solutions → take safe action → evaluate outcomes. These questions are written in an NCLEX-style format to support nursing clinical judgment. They are educational examples, not official NCSBN exam items.