Volume 1 Number 3 - September 30, 1995
Dermatopathologists subclassify neoplasms. It is their
calling. Some are "lumpers" and others are "splitters". None the less,
they all do it. Classification of tumors may seem like birdwatching at
times. To some, there are many kinds of shore-birds. To others, "they's
all killdeers". How many kinds of basal cell carcinomas are there? Some
say only two; completely excised and incompletely excised. Under the
microscope however, we see a wide variety of patterns of growth that
reflect the capacity of basaloid cells to differentiate and mimic the
various normal structures of the skin (hair follicle, epidermis, eccrine
duct, sebaceous gland). Reasons for subclassification of basal cell
carcinomas include: correlation of histologic patterns with clinical
appearance of the tumor, prediction biological behavior, prediction risk
for local recurrence, and guidance for therapy. Several classification
schemes have been offered (see Table 1). We use the classification
according to Lever. In addition we make a diagnosis of "infiltrating
type".
The different patterns of basal cell carcinoma can be
grouped into categories with different relative risks for local recurrence
(see Table 2). Morphea (sclerosing), infiltrating, metatypical and
superficial (multifocal) types have higher risks for recurrence. This
relates to difficulty in clinically determining the extent of tumor.
Morphea, infiltrating and metatypical types of basal cell carcinoma may
also be inherently more aggressive. Cystic and pigmented types are
probably the least likely to recur. Other types are intermediate in
risk.
It is common to see two or more patterns of growth in
biopsies or excisions of basal cell carcinoma. We note the predominant
pattern. If one of the types with more aggressive potential are
identified, this type will also be noted in the diagnosis.
We do not routinely comment upon the margins of biopsies
which contain basal cell carcinoma. We will if specifically requested.
Margins are evaluated on excisions. "Positive margins" indicate that basal
cell carcinoma cells are present at the edges of the specimen and that
tumor has apparently been cut across. We often comment that tumor "appears
close" to a margin. This is used when basal cell carcinoma cells are a
fraction of a millimeter from a margin.
PBG
Table 1
|
HISTOLOGIC
CLASSIFICATIONS OF BASAL CELL CARCINOMA |
| Lever |
Weedon |
UTMCK
(Googe & Fitzgibbon) |
|
solid-primordial |
solid |
keratotic |
solid |
|
keratotic-pilar |
micronodular |
follicular |
cystic |
|
cystic |
cystic |
metatypical |
adenoid |
|
adenoid |
adenoid |
basosquamous |
superficial |
|
morphea-like fibrosing |
sclerosing |
mixtures |
morphea |
|
superficial |
multifocal superficial |
|
metatypical |
|
fibroepithelioma (Pinkus) |
fibroepithelioma |
|
infiltrating |
|
basal squamous metatypical |
pigmented |
|
pigmented |
|
mixtures |
infiltrating |
|
fibroepithelioma |
| |
|
|
mixtures |
Table 2
|
BEHAVIOR OF SUBTYPES
OF BASAL CELL CARCINOMA
RISK FOR LOCAL RECURRENCE |
|
High risk |
Intermediate risk |
Low risk |
|
morphea type |
solid type |
cystic type |
|
infiltrating |
adenoid |
pigmented |
|
superficial |
fibroepithelioma |
|
|
metatypical |
|
|
REFERENCES
Lever WF, Schaumburg-Lever G. Histopathology of the
Skin 1990.
Weedon D. The Skin 1992.
Dixon AY, Lee SH, McGregor DH. Factors predictive of
recurrence of basal cell carcinoma. American J Dermatopathol
1989;11:222-232.
Jacobs GH, Rippey JJ, Altini M. Prediction of aggressive
behavior in basal cell carcinoma. Cancer 1982;49:533-537.
Emmett AJ. Surgical analysis and biological behaviour of
2277 basal cell carcinomas. Aust NZJ Surg 1990;60:855-863.
Dixon AY, Lee SH, McGregor DH. Histologic features
predictive of basal cell carcinoma recurrence: results of a multivariate
analysis. J Cutan Pathol 1993:20:137-142.
Miller SJ. Biology of basal cell carcinoma (Part I). J Am
Acad Dermatol 1991;24:1-13.
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