Basal Cell Carcinoma (BCC)
Info & Pathophysiology
What is it?
Malignancy of keratinocytes (KCs)in stratum basale (if infiltrative, will spread deeper in dermis and subcutaneous tissue); Most common skin carcinoma, least risk of metastasis, and slow growing
Risk Factors: primarily UV sun exposure (causes thymine dimerization/induces mutations)
Clinical Diagnosis: dependent on subtype (see below) but typically pearly, waxy, glossy, raised/rolled edges with telangiectasias
Pathophysiology:
- unregulated growth of KCs at dermal-epidermal junctions
- mutations in sonic hedgehog pathway
- dysregulation of PTCH or TP53 genes
Major Subtypes
Nodular BCC (80%)
Most common subtype
Pink/pearly papule w rolled borders on face, neck
Can ulcerate and bleed, forming rodent ulcer
Superficial BCC (15%)
Thin, pink plaque/papule/macule with border on chest, back, or extremities
Atrophied center
Infiltrative & Morpheaform (5-10%)
Flesh-colored pink atrophic papules; firm and indurated
Presents similarly to nodular BCC but morpheaform BCC can also present as firm, scar-like plaque
Histological Characteristics
Increased visible pigmentation of stratum basale cells, near basement membrane
Peripheral palisading of basaloid nests (see right: more heavily stained cells around clusters)
Peritumoral clefting: masonic tissue in between nests of cells (see right: white gap areas around basaloid nests)
Treatment
Surgical incision (if <20mm in trunk/extremities): breadloaf cuts with 4mm margins assessed post-op
Mohs micrographic surgery: oblique excision, horizontal slices of cuts until no cancerous tissue detected; margins examined during surgery
Curettage & Excision (C&E): for older patients (less concern about scarring), no histological conformation of tumor removal
- Scrape tumor with curette
- Electrodessication with electrical current to destroy remaining cancerous growth
Topical Creams
- Imiquimoid 5%: for superficial BCC 5d/6wk
- 5-Fluorouracil 5%: thymidylate synthase inhibitor
Amytomically 
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