Dermatology Flashcards
1.
A 15-year-old boy presents to his physician
complaining of a rash. He fi rst noticed a dry,
red patch on his back. Then smaller patches
started to appear on his shoulders, and over the
past week, the rash has spread to his trunk. The
rash itches, but he otherwise feels well. He had
a slightly sore throat 2 weeks ago but denies fe-
ver, cough, or other symptoms of upper respi-
ratory infection. He is sexually active with his
girlfriend and they use condoms. He denies
travel or exposure to tick bites. On examination
there are erythematous scaly papules and
plaques as shown in the image. There are no
other significant findings on examination.
Rapid plasma reagin test is negative. Which of
the following is the most likely diagnosis?
(A) Guttate psoriasis
(B) Lyme disease
(C) Pityriasis rosea
(D) Secondary syphilis
(E) Tinea corporis
- The correct answer is C.
Pityriasis rosea may
be preceded by a prodrome of headache, mal-
aise, and/or sore throat, but is most often as-
ymptomatic. The diagnosis is made based on
history and physical examination. The rash is
pruritic and begins with a herald patch. It then
classically spreads downward or centrifugally
on the trunk and proximal extremities. The
herald patch is erythematous, round, and clears
centrally with a peripheral scale. The following
lesions are oval or oblong, with the long axes
aligned with skin cleavage lines. The rash re-
solves spontaneously within 2–3 months. The
etiology of pityriasis rosea is not well under-
stood but is thought to be virally mediated, pos-
sibly secondary to a reactivation of human
herpesvirus-7.
2.
A 14-year-old girl presents to her primary phy-
sician with an intensely pruritic rash on both
hands and on her right cheek. The rash con-
sists of vesicles on erythematous plaques ar-
ranged linearly with slight crusting. She denies
fever or sore throat and otherwise feels well.
She does not have a history of eczema or sick
contacts. Which of the following is the most likely
diagnosis?
A) Atopic dermatitis
(B) Contact dermatitis
(C) Erythema infectiosum
(D) Impetigo
(E) Seborrheic dermatitis
- The correct answer is B.
Contact dermatitis
causes an acute eczematous rash and results
from a type IV hypersensitivity reaction to an
allergen. In this case, the allergen was likely
poison ivy resin because she presents with a
characteristic rash. In addition, the lesions are
arranged perfectly linearly, suggesting that the
cause is external to the patient (i.e., a plant),
rather than an internal dermatologic disease.
3.
A 42-year-old man presents for evaluation of a
mole on his back that his wife noticed has
changed in size. She is not present but told
him that it used to be smaller. He is fair
skinned and admits to never using sunscreen.
He has always had numerous freckles and
moles but has no personal or family history of
skin cancer. Examination shows the lesion
seen in the image. He also has approximately
30 other small, round nevi on his arms and
back. Which of the following features is most
predictive of poor outcome in this case?
A) Asymmetric shape
(B) Diameter >6 mm
(C) Irregular borders
(D) Tumor thickness
(E) Variation in color
- The correct answer is D.
The lesion pictured
is a malignant melanoma. Melanomas are rec-
ognizable by the
ABCDEs (Asymmetric shape, Borders irregular, Color
variation, Diameter>6 mm, and Enlargement or
Evolution of the lesion). This mnemonic is a useful way
for both patients and physicians to recognize when
a previously ordinary mole should be evaluated
for melanoma. However, this mnemonic is not
useful for determining the prognosis for sur-
vival of a patient with primary melanoma. Tu-
mor thickness (or Breslow depth) determined
on biopsy has been shown to be the most pow-
erful prognostic factor in primary melanomas.
4.
A 26-year-old man presents to the emergency
department with burns on his chest. He had a
fight with his girlfriend and she threw boiling
water at him, splashing his chest and arms. The
burns occurred about an hour ago, and are dis-
tributed on the upper third of his left anterior
trunk and cover most of his left proximal arm.
The patient’s temperature is 37.4°C (99.4°F),
blood pressure is 127/74 mm Hg, pulse is 80/
min, respiratory rate is 18/min, and oxygen satu-
ration is 99% on room air. The burns are quite
painful, swollen, and erythematous, with blister
formation. The application of pressure produces
blanching and is quite painful. Which of the
following is the most appropriate management?
(A) Admission to hospital and intravenous antibiotic administration
(B) Cleaning and dressing of the burns, and analgesics as needed
(C) Lubricant application and analgesics asneeded
(D) Referral to a burn center
(E) Surgical evaluation for debridement and grafting
- The correct answer is B.
The burns described
here are superfi cial partial-thickness burns (also
called second-degree burns, affecting the epi-
dermis and portions of the dermis), involving
approximately 10% of his body surface area
(BSA) according to the “rule of nines” (anterior
trunk represents 18% BSA total, so one-third =
6%, and each arm represents 9%, so one-half =
4.5%). Pain, swelling, and blistering helps dis-
tinguish partial-thickness burns. These burns
can be managed in the ambulatory setting, with
appropriate cleansing, debridement if necessary,
dressing, and appropriate pain management.
These burns should heal in 1 to 3 weeks with
minimal scarring, but may potentially result in
pigmentation changes. First-degree burns, such
as the typical sunburn, affect the epidermis only.
Tissue is erythematous and blanches to pres-
sure, and damage is minimal. Healing occurs
spontaneously. Third-degree burns, or full-thick-
ness burns, affect the entire epidermis and der-
mis. The area of the burn itself is painless,
though surrounding tissue is usually tender due
to adjacent areas of partial-thickness burn. The
skin may be charred or white in color, with vis-
ible blood vessels. Healing is slower than with
less severe burns, because sweat glands and
hair follicles (the source of skin stem cells) are
destroyed. Fourth-degree burns involve under-
lying muscle and/or bone.
5.
A 47-year-old man with no significant past
medical history presents to the office complaining
of a new rash in his armpits. He first no-
ticed it 1 month ago, and since then it has
grown “darker, thicker, and larger.” He reports
that it is occasionally mildly pruritic. His vital
signs are normal. Upon examination he has hy-
perpigmented thick plaques in both axillae
(see image). Physical examination is otherwise
unremarkable. Which of the following is the
most appropriate laboratory test to order?
(A) Cosyntropin stimulation test
(B) Fasting blood glucose
(C) Fasting lipid panel
(D) Serum electrolytes
(E) Thyroid-stimulating hormone
- The correct answer is B.
Acanthosis nigricans
is a dermatologic finding characterized by hy-
perpigmented and thickened patches that are
most often found in the axillae or on the back
of the neck, but that are occasionally found in
other skin fold areas or on the hands. The finding
is most commonly associated with diabetes
mellitus or insulin resistance; thus, the most
appropriate laboratory test would be a fasting
blood sugar level.
6.
A 47-year-old man with a history of recent sub-
clinical hepatitis C infection presents com-
plaining of rash and mouth pain for the past
week. The rash is pruritic. Examination reveals
lesions on his wrists, ankles, and scalp; the le-
sions are shiny, violaceous, sharply demar-
cated, confl uent papules containing fine white
lines in a lacy pattern on their surfaces. Exami-
nation of his oropharynx reveals an erosion on
the left buccal mucosa with the same fine
white reticulation. Which of the following is
the most likely diagnosis?
(A) Erythema multiforme
(B) Hypersensitivity vasculitis
(C) Lichen planus
(D) Secondary syphilis
(E) Viral exanthema
- The correct answer is C.
This is a classic de-
scription of lichen planus; remember the “
5 P’s ”: Purple, Polygonal, Pruritic, and Planar Papules
and Wickham’s striae (the characteris-
tic light grey or white lines or dots seen on the
surface of lichen planus). Lichen planus is an
uncommon disease of unclear though possibly
autoimmune etiology. It affects middle-aged
adults and may be associated with hepatitis C
infection and/or drug exposure (including
β-blockers, penicillamines, angiotensin-convert-
ing enzyme inhibitors, and sulfonylureas). Li-
chen planus is often self limited, resolving
within 8–12 months. Antihistamines and topical
corticosteroids are recommended for milder
cases. Systemic steroids (e.g., intramuscular tri-
amcinolone every 3 months) or oral psoralen
with ultraviolet A light therapy may be effective
for managing severe symptoms; however, the
patient should be made aware of the increased
adverse effects.
7.
A 19-year-old woman presents to her primary
care physician complaining of excessive bruis-
ing on her legs for the past 3 days. She denies
injury. She was treated for streptococcal throat
infection 10 days ago and recently completed
antibiotic therapy. She has had some cramping
abdominal pain, but she is premenstrual and
says the pain is similar to her usual cramps.
She took ibuprofen for the pain, with good re-
lief. She has a boyfriend but is not sexually ac-
tive. She denies previous history of bruising or
bleeding easily. Inspection of her legs reveals
diffuse tender, erythematous, indurated patches
and nodules over the anterior aspects of her
tibias bilaterally. Which of the following is the
most likely cause of her symptoms?
(A) Domestic violence
(B) Erythema nodosum
(C) Henoch-Schönlein purpura
(D) Idiopathic thrombocytopenic purpura
(E) Secondary syphilis
- The correct answer is B.
Pretibial erythema-
tous, tender nodules in a young woman is a
classic presentation of erythema nodosum
(EN), which is caused by infl ammation of sub-
cutaneous fat. Most cases of EN are idiopathic.
The second most common cause of EN is strep
pharyngitis, and other known causes include
hypersensitivity reaction secondary to drugs
(e.g., oral contraceptives and nonsteroidal anti-
inflammatory drugs), sarcoidosis, tuberculosis,
and infl ammatory bowel disease.
8.
A 25-year-old HIV-positive man presents to his
primary physician because he has been ex-
posed to herpes. He is concerned because he
had a friend with AIDS who developed a fatal
disseminated herpes infection and is afraid the
same thing might happen to him. The expo-
sure occurred 2 days ago when he shared an
ice cream bar with his niece, whom he noticed
afterward had an oral lesion. To his knowledge
he has never had an oral lesion. Neither he nor
his partner has ever had “cold sores.” Which of
the following is the most appropriate approach
to this patient?
(A) Admit to hospital for initiation of intrave-
nous anti-herpes simplex virus immunoglobulin therapy
(B) Admit to hospital for intravenous acyclovir therapy
(C) Follow patient closely for development of
complications, but it is too late to initiate
acyclovir therapy
(D) Prescribe oral acyclovir, five times daily for
7 days and follow closely for clinical disease
(E) Reassure him that he is unlikely to develop
severe disease and that he will probably
contract herpes simplex virus-1 sooner or later
- The correct answer is D.
From the history, it is
possible that this is the patient’s first exposure
to herpes simplex virus (HSV). In patients with
HIV, a 7-day course of oral acyclovir has been
shown to reduce the duration and morbidity
associated with HSV infection, and there may
also be a role for acyclovir in prophylaxis if ad-
ministered soon after exposure.
9.
A 68-year-old man presents to his primary care
physician for evaluation of “scabs” on his ear
that have failed to resolve over the past year.
He is a retired vineyard manager and has
worked outside for most of his career. He does
not have any family or personal history of skin
cancer. On examination he has two macular,
scaling lesions on his face, 2 and 4.5 mm in di-
ameter. They are hyperkeratotic with surround-
ing erythema (see image). These lesions should
be biopsied and observed carefully to prevent
which of the following?
(A) Local extension and tissue destruction
(B) Progression to basal cell carcinoma
(C) Progression to malignant melanoma
(D) Progression to squamous cell carcinoma
(E) This lesion does not have malignant
potential and further evaluation is not necessary
- The correct answer is D.
This is a case of ac-
tinic keratosis (AK), which can be differenti-
ated from seborrheic keratosis by the presence
of an erythematous base. In addition, sebor-
rheic keratoses are typically darker, ranging
from brownish-pink to black. The primary risk
factor for development of AK is sun exposure.
The risk of an AK progressing to squamous cell
carcinoma (SCC) is small; however, approxi-
mately half of cutaneous SCCs arise from AK.
10.
A 55-year-old woman presents to her gynecolo-
gist complaining of vaginal discomfort. It first
started approximately 6 months ago and has
fluctuated in intensity, most recently causing
itching and some slight pain when she has in-
tercourse with her husband. She otherwise has
been well. She has been postmenopausal for 3
years. Her older sister recommended an estro-
gen cream, which she has used consistently for
>3 months without any change in symptoms.
On examination the introital mucosa and labia
minora are whitish-pink, with abnormal wrin-
kling and a small fi ssure on the right labia mi-
nora. Which of the following is the most likely
diagnosis?
(A) Candidiasis
(B) Estrogen deficiency
(C) Lichen planus
(D) Lichen sclerosus
(E) Sexual abuse
- The correct answer is D.
Lichen sclerosus
(also called lichen sclerosus et atrophicus) is
most common in postmenopausal women, and
causes itching of the anogenital region. How-
ever, it can occur at all ages and in both sexes
and can be found anywhere on the skin.
Though the etiology is unknown, chronic in-
fl ammation is thought to play a role in causing
the labia to become white, wrinkled, and fragile.
The tissue may be so fragile that minor
trauma may cause petechial bleeding or fissures, as
seen in this case. The patient described
here has early disease. More advanced
disease may cause loss of labial distinction and
fusing of the prepuce, obscuring the urethra
and clitoris. Definitive diagnosis is made by bi-
opsy, and treatment is with an ultrapotent topi-
cal corticosteroid applied daily for several
weeks and then less frequently in the longterm.
