Basal Cell
Carcinoma (BCC)
Common sites:
- Sun-exposed
sites
- Not
mucosal surfaces
Gross features:
Histologic
features:
- uniform
tumour cells resembling normal basal cell layer
of epidermis
- pallisading edges
- separation
artifact between stroma and nests
- may
have numerous mitotic
figures
- abundant
apoptosis
- mucin deposition in stroma
- nodular
(most common):
- cords
and islands
- growing
deep into dermis
- variably
basophilic cells
- hyperchromatic nuclei
- embedded
in a mucinous matrix
- often
surrounded by many fibroblasts and lymphocytes
- multifocal
superficial type:
- multifocal
growths originating from the epidermis
- do
not extend below superficial dermis (unless associated with another type
of BCC)
- extending
over several square centimeters of skin surface
- sclerosing type (morphea type):
- slender
nests
- deeply
infiltrative
- reactive
(++inflammatory cells) stroma composing
>50% of the tumour bulk
- keratotic type:
- often
misdiagnosed as squamous cell carcinoma
- keratinization present
- numerous
apoptotic keratinocytes
- relatively
regular cytologic features
- abundant
stroma
- keratotic (infundibulocystic,
pilar) type:
- differentiation
towards hair follicle infundibulum
- continuity
with overlying epidermis and adjacent hair follicles
- budlike
structures as well as follicular bulbs and dermal papillae
- solid
and reticulated pattern of growth
- squamous-appearing basaloid cells with amphophilic
cytoplasm
- cysts
lacking a granular cell layer filled with keratin and parakeratotic material
- ulcerated
BCCs often have superficial keratinization
- may be
pigmented (melanin) = pigmented type
- symbiotic
non-tumoral proliferating melanocytes
- may
produce mucin
- intralobular and stromal collections (basophilic)
- cells
with a signet ring appearance
- may have amyloid deposition (50-75%)
- may hav e glandular pattern (adenoid type)
- may
have sebaceous differentiation
- may be
largely cystic
- may
have granular or clear cytoplasm
- amyloid may be present in large
quantities
Immunophenotype:
Marker:
|
Sensitivity:
|
Specificity:
|
CK5
|
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CK14
|
|
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Ber-EP4
|
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Molecular features:
- X
chromosome inactivation
- PATCHED
gene mutations
Other features:
- rarely
metastasize
- increased
risk of recurrence in sclerosing and
superficial types
- multiple
BCCs in Basex syndrome and Gorlin’s
syndrome (Nevoid basal cell carcinoma syndrome)
- adverse
prognostic factors:
- histologic subtypes:
- infiltrative subtype
- morpheaform (sclerosing)
subtype
- micronodular subtype
- invasion
into deep subcutaneous fat, muscle, or cartilage
- perineural invasion
- surgical
margin positivity
- presence
of scar within tumour
References:
- Essentials of AP 2006
- Sternberg
2004