Dermatology · Skin Cancer
The facts most likely to be tested
Basal cell carcinoma is the most common skin malignancy in humans, typically arising from the basal layer of the epidermis.
The classic clinical presentation is a pearly, flesh-colored papule with rolled borders and telangiectasias.
Chronic ultraviolet (UV) light exposure is the primary environmental risk factor for the development of these lesions.
Lesions frequently exhibit central ulceration, often described as a rodent ulcer if left untreated for an extended period.
The gold standard for definitive diagnosis is a shave or punch biopsy showing palisading nuclei on histopathology.
Mohs micrographic surgery is the treatment of choice for lesions located on the face, nose, or ears to maximize tissue preservation.
Basal cell carcinoma has a very low metastatic potential, but it is locally invasive and can cause significant tissue destruction.
Vignette unlocked
A 68-year-old male presents to the clinic for a persistent lesion on his left nasal ala that has been present for several months. He reports that the lesion occasionally bleeds when he wipes his face. Physical examination reveals a 0.8 cm pearly, flesh-colored papule with prominent telangiectasias and rolled borders. There is a small area of central ulceration noted on the surface. The patient has a significant history of outdoor work as a landscaper for 40 years.
What is the most appropriate next step in management?
Excisional biopsy (or shave biopsy) for histopathologic confirmation
The vignette describes the classic presentation of basal cell carcinoma, and a biopsy is required to confirm the diagnosis before proceeding to definitive treatment like Mohs surgery.
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Etiology / Epidemiology
Most common skin cancer; UV radiation exposure is the primary risk factor.
Clinical Manifestations
Pearly papule with rolled borders and telangiectasias.
Diagnosis
Punch biopsy or shave biopsy is the gold standard for definitive diagnosis.
Treatment
Mohs micrographic surgery is the first-line treatment for high-risk facial lesions.
Prognosis
Excellent prognosis with >95% cure rate; low metastatic potential.
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Epidemiology & Etiology
BCC is the most common malignancy in humans, strongly associated with cumulative UV exposure and intermittent intense sun exposure. Incidence increases with age and is highest in individuals with Fitzpatrick skin types I and II. Chronic immunosuppression and history of ionizing radiation are secondary risk factors.
Pertinent Anatomy
Arises from the basal layer of the epidermis. Lesions are most frequently located on the sun-exposed areas of the head and neck, particularly the nose.
Pathophysiology
Driven by mutations in the Hedgehog signaling pathway, specifically the PTCH1 tumor suppressor gene. Loss of PTCH1 function leads to constitutive activation of the Smoothened protein, promoting uncontrolled cellular proliferation. This molecular pathway is the target for systemic therapy in advanced cases.
Clinical Manifestations
Presents as a pearly, flesh-colored papule with prominent arborizing telangiectasias. Classic morphology includes rolled borders and central ulceration, often described as a rodent ulcer. Bleeding with minor trauma is a common patient complaint. High-risk features include location in the 'H-zone' of the face or size >2 cm.
Diagnosis
Clinical suspicion must be confirmed via skin biopsy. A shave biopsy is typically sufficient for diagnosis, though a punch biopsy may be preferred for deeper lesions. Histopathology reveals nests of basaloid cells with peripheral palisading.
Treatment
Mohs micrographic surgery is the gold standard for facial lesions to ensure clear margins while sparing tissue. Electrodessication and curettage is acceptable for low-risk trunk/extremity lesions. For patients who are not surgical candidates, vismodegib (a Hedgehog pathway inhibitor) is used for metastatic or locally advanced disease.
Prognosis
Extremely low risk of metastasis, but local tissue destruction can be significant if neglected. Patients require annual skin exams due to a high risk of developing subsequent primary BCCs.
Differential Diagnosis
Squamous Cell Carcinoma: typically scaly, hyperkeratotic, and lacks telangiectasias
Amelanotic Melanoma: often lacks pigment but exhibits rapid growth and asymmetry
Sebaceous Hyperplasia: yellow-colored papule with central umbilication
Actinic Keratosis: rough, sandpaper-like texture on sun-damaged skin
Intradermal Nevus: stable, long-standing lesion without ulceration