Does Transecting a
Melanoma on Initial
Biopsy Affect the
Biopsies of pigmented lesions often aim for complete
removal, but in many clinical situations, a lesion is partially
sampled. When a biopsy has a positive deep or lateral margin,
clinical information is incomplete and may not be able to be
reconstructed after subsequent procedures. In addition to
confounding clinical information for prognosis and treatment,
there is a theoretical risk of adverse clinical outcomes caused
by melanoma transection. Fortunately, new evidence confirms
that incisional biopsy of melanoma, while not ideal, is not
associated with worsened clinical outcomes.
When suspicion is high for melanoma, excisional biopsy is
almost always the diagnostic test of choice. Biopsies of pigmented
lesions often aim for complete removal, but in many
clinical situations, a lesion is partially sampled. The partial
sampling may be deliberate, as with a large or cosmetically
sensitive lesion, or may be found incidentally on histopathologic
examination. Some pigmented lesions are transected at the
deep margin, and others at a lateral margin. When the lesion
in question is a melanoma, these partial sampling challenges
can lead to errors in correct diagnosis (most importantly, tumor
depth) and potentially can complicate therapy and outcomes.
Hypothetically, incisional biopsy could spread tumor cells locally
or via blood or lymph vessels, or could trigger a wound
healing response that could also promote tumor cell growth.
Initial data suggested that incisional biopsy could lead to
poorer clinical outcomes. However, incisional biopsy is often
obtained on large melanomas or those in difficult-to-treat areas
such as the head and neck and may lead to a selection bias for
incisional biopsy for tumors with poorer outcomes.
Partial sampling errors have a role in medical malpractice, and at
least 30% of pathology cases among a set of claims in California
were due to missed melanoma diagnoses. In a large US physician
insurer, The Doctors Company, more than 50% of the false-negative
missed melanoma diagnosis cases were due to partial sampling.1
New, larger studies reviewed here have addressed the incidence
of partial biopsy for melanoma and its effect on outcomes. Fortunately,
these data confirm that while not ideal, partial sampling or
transection of melanoma does not significantly affect long-term outcomes. These studies retrospectively analyze confirmed melanoma
cases rather than detecting potentially missed diagnoses.
The largest case-control series analyzed the Scottish Melanoma
Group's tumor registry from 1979 to 1995 to evaluate whether
incisional biopsy of melanoma might affect prognosis compared
with excisional biopsy.2 This group of cases included only invasive
melanoma that was diagnosed by incisional biopsy, and each was
compared with 2 controls that had only excisional biopsy. Groups
were matched by Breslow thickness as thin (<1.5 mm), intermediate
(1.5 to 3 mm), or thick (>3 mm) melanoma. Clinical outcomes
were time to melanoma recurrence and melanoma-specific mortality.
Among more than 5,700 melanoma patients, only 321 had
incisional biopsy before definitive excision. Two hundred seventy
invasive melanomas diagnosed by incisional biopsy were
matched to 496 controls based on age, gender, tumor depth, and
tumor location. The main outcome measures were time from initial
biopsy to tumor recurrence and to melanoma-related death.
Their analysis showed that biopsy type had no significant effect
on recurrence (P=.30) or melanoma-related death (P=.34). This
population is notable in being limited to individuals with invasive
melanomas and having a larger proportion, approximately
36%, of deep melanoma cases. Subungual, mucosal, and palm
and sole melanomas were underrepresented because appropriately
matched controls were not always available in the group.
In 2010, an Australian tertiary referral center compared partial
and excisional biopsy techniques in a series of more than 2,400
consecutive cases of melanoma referred between 1995 and
2006.3 In Australia, excisional biopsy was overwhelmingly the
preferred diagnostic technique. At least 2,000 of the 2,400 cases
were evaluated with excisional biopsy, and fewer than 200 each
were diagnosed with shave or punch biopsy. Odds ratios were
compared for rates of correct diagnosis.
Researchers compared excisional biopsy, shave biopsy, and punch
biopsy on rates of misdiagnosis. Other factors considered were
anatomic site, physician type at initial management, hypomelanosis,
melanoma subtype, biopsy sample size, multiple biopsies, and
tumor thickness. Missed diagnoses were examined for both falsepositive
and false-negative results, and false-negative results were
further classified as to whether they led to an adverse outcome.
For the purposes of this study, an adverse outcome was defined
as the persistence or progression of primary disease or development
of nodal or distant metastasis occurring before the correct
diagnosis. False-negative cases were usually detected on definitive
excision, though cases were at times diagnosed as dysplastic
nevi or nonmelanoma skin cancer and reclassified on reexcision,
or were repeatedly sampled because of lesion persistence or clinical
progression. Most false-positive lesions were reclassified after
excision as benign nevi, dysplastic nevi, or Spitz nevi.