LATEST MICROGRAPHIC DERMATOLOGIC
SURGERY (MOHS SURGERY) CERTIFICATION
EXAM OFFERED BY AMERICAN BOARD OF
DERMATOLOGY | COMPLETE EXAM Q&A WITH
RATIONALES
1. A 72-year-old male with a 2 cm basal cell
carcinoma (BCC) on the nasal ala has no prior
treatment. Which is the most appropriate indication
for Mohs micrographic surgery (MMS)?
A) Tumor size >1 cm on the nose
B) Recurrent tumor
C) Ill-defined clinical margins
D) All of the above
Correct answer: D
Rationale: MMS is indicated for tumors in high-risk
locations (nose, ears, eyelids, lips, hands, genitals),
large size (>1 cm), aggressive histology, recurrent
tumors, and ill-defined margins.
2. A 68-year-old female with a 1.5 cm morpheaform
BCC on the left cheek undergoes MMS. The first
stage shows residual tumor at the deep margin only.
Which is the most appropriate next step?
,A) Excise a second stage from the deep margin only
B) Excise a second stage from the peripheral and
deep margins
C) Close the defect primarily
D) Refer for radiation therapy
Correct answer: A
Rationale: In MMS, if the deep margin is positive and
peripheral margins are negative, only the deep
margin is re-excised in the next stage.
3. A 55-year-old male with a 3 cm recurrent
squamous cell carcinoma (SCC) on the right temple
undergoes MMS. The tumor is fixed in paraffin for
permanent sections after mapping. Which is the most
critical step to ensure accurate margin assessment?
A) Color-coding the tissue with different dyes
B) Flattening the tissue to a single plane
C) Sectioning at 4-micron thickness
D) Staining with hematoxylin and eosin (H&E)
Correct answer: A
Rationale: Color-coding (different colored dyes for
different tissue segments) allows precise orientation
and mapping of tumor location.
,4. A 70-year-old female with a 2 cm superficial BCC
on the central forehead undergoes MMS. Frozen
sections show clear margins. Which closure is most
appropriate?
A) Linear closure
B) Full-thickness skin graft
C) Secondary intention healing
D) Advancement flap
Correct answer: A
Rationale: The forehead (central) often allows linear
closure due to skin laxity and RSTLs.
5. A 65-year-old male with a 1.8 cm nodular BCC on
the nasal tip undergoes MMS. The first stage shows
tumor at the deep and peripheral margins. The
second stage after re-excision shows clear margins.
The resulting defect is 2.5 cm. Which repair is most
appropriate for the nasal tip?
A) Bilobed flap
B) Full-thickness skin graft (FTSG)
C) Nasolabial flap
D) Secondary intention healing
, Correct answer: A
Rationale: Bilobed flap is ideal for nasal tip defects up
to 2.5 cm, using adjacent skin from the nasal dorsum
and sidewall.
6. A 62-year-old female with a 1.2 cm infiltrative BCC
on the right medial canthus undergoes MMS. Which
structure is at highest risk for involvement?
A) Punctum
B) Canthal tendon
C) Lacrimal sac
D) Orbital fat
Correct answer: B
Rationale: The medial canthal tendon (canthal
tendon) is a common site of periorbital BCC
extension.
7. A 58-year-old male with a 2.5 cm recurrent SCC on
the left helix undergoes MMS. The tumor extends to
the perichondrium but not through it. Which is the
most appropriate next step?
A) Deepen the excision to include the perichondrium
B) Remove cartilage and reconstruct with conchal
graft
SURGERY (MOHS SURGERY) CERTIFICATION
EXAM OFFERED BY AMERICAN BOARD OF
DERMATOLOGY | COMPLETE EXAM Q&A WITH
RATIONALES
1. A 72-year-old male with a 2 cm basal cell
carcinoma (BCC) on the nasal ala has no prior
treatment. Which is the most appropriate indication
for Mohs micrographic surgery (MMS)?
A) Tumor size >1 cm on the nose
B) Recurrent tumor
C) Ill-defined clinical margins
D) All of the above
Correct answer: D
Rationale: MMS is indicated for tumors in high-risk
locations (nose, ears, eyelids, lips, hands, genitals),
large size (>1 cm), aggressive histology, recurrent
tumors, and ill-defined margins.
2. A 68-year-old female with a 1.5 cm morpheaform
BCC on the left cheek undergoes MMS. The first
stage shows residual tumor at the deep margin only.
Which is the most appropriate next step?
,A) Excise a second stage from the deep margin only
B) Excise a second stage from the peripheral and
deep margins
C) Close the defect primarily
D) Refer for radiation therapy
Correct answer: A
Rationale: In MMS, if the deep margin is positive and
peripheral margins are negative, only the deep
margin is re-excised in the next stage.
3. A 55-year-old male with a 3 cm recurrent
squamous cell carcinoma (SCC) on the right temple
undergoes MMS. The tumor is fixed in paraffin for
permanent sections after mapping. Which is the most
critical step to ensure accurate margin assessment?
A) Color-coding the tissue with different dyes
B) Flattening the tissue to a single plane
C) Sectioning at 4-micron thickness
D) Staining with hematoxylin and eosin (H&E)
Correct answer: A
Rationale: Color-coding (different colored dyes for
different tissue segments) allows precise orientation
and mapping of tumor location.
,4. A 70-year-old female with a 2 cm superficial BCC
on the central forehead undergoes MMS. Frozen
sections show clear margins. Which closure is most
appropriate?
A) Linear closure
B) Full-thickness skin graft
C) Secondary intention healing
D) Advancement flap
Correct answer: A
Rationale: The forehead (central) often allows linear
closure due to skin laxity and RSTLs.
5. A 65-year-old male with a 1.8 cm nodular BCC on
the nasal tip undergoes MMS. The first stage shows
tumor at the deep and peripheral margins. The
second stage after re-excision shows clear margins.
The resulting defect is 2.5 cm. Which repair is most
appropriate for the nasal tip?
A) Bilobed flap
B) Full-thickness skin graft (FTSG)
C) Nasolabial flap
D) Secondary intention healing
, Correct answer: A
Rationale: Bilobed flap is ideal for nasal tip defects up
to 2.5 cm, using adjacent skin from the nasal dorsum
and sidewall.
6. A 62-year-old female with a 1.2 cm infiltrative BCC
on the right medial canthus undergoes MMS. Which
structure is at highest risk for involvement?
A) Punctum
B) Canthal tendon
C) Lacrimal sac
D) Orbital fat
Correct answer: B
Rationale: The medial canthal tendon (canthal
tendon) is a common site of periorbital BCC
extension.
7. A 58-year-old male with a 2.5 cm recurrent SCC on
the left helix undergoes MMS. The tumor extends to
the perichondrium but not through it. Which is the
most appropriate next step?
A) Deepen the excision to include the perichondrium
B) Remove cartilage and reconstruct with conchal
graft
