ROSH REVIEW Dermatology | Questions & Answers (100 %Score) Latest Updated
2024/2025 Comprehensive Questions A+ Graded Answers | With Expert Solutions
24-year-old man presents for evaluation of a rash. The patient reports a mildly pruritic
rash on his back and trunk that progressively spread over the last week. You examine
and note the rash seen above. Which of the following historical elements is most likely
to be obtained upon further questioning?
A larger 2 to 5 cm erythematous patch preceded the diffuse rash
Fever preceded the onset of rash
Oral mucosal lesions preceded the onset of rash
Travel to the Southeast USA occurred a week before the rash - Correct Answer ( A )
Explanation:
This patient has pityriasis rosea. This is a mild skin eruption that is self-limited usually
lasting 4 to 7 weeks. There is no clear etiology of the rash although infection with
Herpesvirus 7 or a fungus is suspected. Prior to the onset of the diffuse rash, patients
may recall a herald patch described as a 2 to 5 cm erythematous oval plaque similar to
the smaller more diffuse lesions. The rash is described as following a "Christmas tree"
pattern on the trunk, classically following the skin cleavage lines. There is no indicated
treatment for pityriasis rosea other than antihistamines for symptomatic relief if the rash
is pruritic.
A history of travel to the Southeast USA (D) before the onset of rash should raise an
index of suspicion for an infectious etiology to the rash like Rocky Mountain Spotted
fever, a tick-borne illness caused by Rickettsia rickettsii. This illness occurs most
commonly in late spring and early summer and is characterized by a rash that starts
distally and spreads to the core.
One Step Further
Question: Is the rash of pityriasis rosea contagious? - Answer: No, the rash cannot be
spread by direct contact.
An 18-year-old obese woman presents to your office with a complaint of redness and
pain in her right axilla. Physical exam reveals a solitary nodule, approximately 2 cm in
size, with surrounding inflammation and erythema. She tells you that she's had similar
"boils" in the past. Which of the following is the most likely diagnosis?
Contact dermatitis
Dermoid cyst
Granuloma inguinale
Hidradenitis suppurativa - Correct Answer ( D )
Explanation:
Hidradenitis suppurativa (HS) is a chronic inflammatory skin condition that causes
scarring, keloids, contractures and immobility. Originally believed to be caused by a
defect in the apocrine glands, it may also be due to a defect in the follicular epithelium.
,HS begins in adolescence or adulthood in otherwise healthy individuals. Risk factors for
the development of HS include obesity, genetics, smoking, diet and mechanical stress
on the skin. Onset is insidious, with the first presentation generally being erythema in an
intertriginous skin area, most commonly the axilla. As the disease progresses, formation
of sinus tracts, multiple open comedomes and scarring occur. The initial presentation
can mimic other disorders and individuals often are diagnosed incorrectly with recurrent
furunculosis. Diagnosis is a clinical one. Treatment includes medical management in the
early stages and surgical intervention after the formation of abscesses or sinus tracts.
One Step Further
Question: What is the other name for hidradenitis suppurativa? - Answer: Acne inversa.
A 60-year-old man with a history of diabetes presents to your office with a complaint of
thickened and discolored toenails. He tells you that his toenails have had this
appearance for over a year, and now he is experiencing discomfort when wearing tight-
fitting shoes. Physical exam reveals hyperkeratosis and onycholysis of bilateral great
and second toes. Which of the following is the most appropriate next step in
management?
Begin treatment with oral terbinafine
Check serum aminotransferases
Potassium hydroxide examination of toenail scrapings
Watchful waiting - Correct Answer ( C )
Explanation:
Onychomycosis is a fungal infection of the toenails or fingernails that can involve any
part of the nail including the plate, bed or matrix. There are several subtypes of
onychomycosis, with the most common being distal subungual onychomycosis. This
type presents with the great toe being the first affected. A white, yellow or brown
discoloration can be seen that eventually spreads to the entire nail. Onycholysis, the
separation of the nail from the plate, may also be seen. Onychomycosis is initially a
cosmetic concern, however with time it can cause pain, disfigurement, and decreased
quality of life. Other nail dystrophies can present similarly to onychomycosis, therefore
establishing the presence of a fungal etiology is recommended prior to initiation of
treatment. Diagnosis is with potassium hydroxide (KOH) examination of nail scrapings.
Patients who are immunocompromised or who have diabetes mellitus are at an
increased risk of bacterial infections due to onychomycosis. Treatment should be
considered in these patients to avoid sequelae.
Once a fungal etiology has been determined, first-line treatment is with oral antimycotic
agents such as terbinafine (A). Terbinafine can cause hepatotoxicity, so pretreatment
serum aminotransferases (B) should be measured prior to initiating therapy and then
monitored during the course of treatment.
One Step Further
Question: What is the most common etiology of onychomycosis? - Answer:
Dermatophyte infection.
,A 18-year-old woman presents with a diffuse papulosquamous rash. The rash began
one month prior when she noticed a large patch on her neck that was followed by the
diffuse papulosquamous rash. You inform the patient that the rash will last 5-8 weeks
and prescribe her cetirizine. Which of the following is the most likely diagnosis?
Contact dermatitis
Pityriasis rosea
Scabies
Tinea versicolor - Correct Answer ( B )
Explanation:
Pityriasis rosea is a common acute eruption usually affecting children and young adults;
the cause is unknown. It is characterized by the formation of an initial herald patch,
followed by the development of a diffuse papulosquamous rash. Pityriasis rosea is
difficult to identify until the appearance of characteristic, smaller, secondary lesions that
follow Langer's lines. The rash of pityriasis rosea typically lasts 8 to 12 weeks, with
complete resolution in most patients. An important goal of treatment is to control
pruritus, which may be severe; zinc oxide, calamine lotion, topical steroids, and oral
antihistamines are usually helpful. Systemic steroids are generally not recommended.
Patients should be reassured about the self-limited nature of pityriasis rosea.
Persistence of the rash or pruritus beyond 12 weeks should prompt reconsideration of
the original diagnosis, consideration of biopsy to confirm the diagnosis, and questioning
the patient again about use of medications that may cause a rash similar to that of
pityriasis rosea.
A 16-year-old boy is in the clinic with his father for a sports physical examination. He
participates in wrestling in school. He eats a healthy diet. Family history is negative for
heart disease or sudden death in a relative younger than 50 years of age. He denies
shortness of breath, chest pain, palpitations, or loss of consciousness. On physical
examination, heart rate is 75 beats per minute, respiratory rate is 16 cycles per minute,
temperature is 36.5 oC, body mass index is at the 87th percentile, clear breath sounds,
no murmur, soft abdomen. On skin examination, there is an annular plaque with central
clearing and a raised border measuring about 5 cm in diameter. There are fine scales
present. Which of the following is the most likely diagnosis?
Granuloma annulare
Nummular eczema
Subacute cutaneous lupus erythematosus
Tinea corporis - Correct Answer ( D )
Explanation:
The boy has skin examination findings consistent with tinea corporis. Tinea corporis is a
cutaneous dermatophyte infection occurring in sites other than the feet, groin, face, or
hand. Trichophyton rubrum is the most common cause of tinea corporis. Acquisition of
infection may occur by direct skin contact with an infected individual or animal, contact
with fomites, or from secondary spread from other sites of dermatophyte infection. Tinea
corporis often begins as a pruritic, circular or oval, erythematous, scaling patch or
, plaque that spreads centrifugally. Central clearing follows, while an active, advancing,
raised border remains. The result is an annular (ring-shaped) plaque from which the
disease derives its common name. Multiple plaques may coalesce. Pustules
occasionally appear. A potassium hydroxide (KOH) preparation will show the
segmented hyphae characteristic of dermatophyte infections. The highest yield is
obtained from skin scrapings taken from the active border of a plaque. A fungal culture
is an alternative, albeit slower method for diagnosis.
Granuloma annulare (A) is a benign inflammatory condition that classically presents
with one or more erythematous or violaceous annular plaques on the extremities. Unlike
tinea corporis, scale is absent. Nummular eczema (B) typically presents with highly
pruritic, round, coin-shaped patches of eczematous dermatitis ranging in diameter from
1 to 10 cm. In the acute phase, lesions are dull red, exudative, and crusted. Over time,
they become more dry and scaly, occasionally with central clearing leading to annular
lesions. The legs and the upper extremities are the sites most frequently involved.
Subacute cutaneous lupus erythematosus (C) can be idiopathic or occur in association
with systemic lupus erythematosus or drug exposure. It
Which of the following is the most common infection associated with erythema
multiforme?
Borrelia burgdorferi
Haemophilus influenzae Type b
Hepatitis C virus
Herpes simplex virus - Correct Answer ( D )
Explanation:
Although numerous infections have been reported in association with erythema
multiforme (EM), herpes simplex virus (HSV) is the most common and best
documented. Recurrent EM also is associated with infection with HSV. Demonstration
of prior exposure to HSV by serology and documentation of a cutaneous recurrence of
HSV infection was noted in a series of patients with recurrent EM and was less common
in patients with a single episode. The pathogenesis of EM is incompletely understood,
but evidence increasingly implicates a host-specific, cell-mediated immune response to
an antigenic stimulus that targets keratinocytes at the dermal-epidermal junction. EM
has variable cutaneous manifestations. EM is characterized by the acute onset of a
symmetric, fixed cutaneous eruption of erythematous macules, papules, vesicles, or
bullae most commonly distributed on the palms, dorsal surfaces of the hands and feet,
and extensor surfaces of the arms and legs with relative sparing of the face, trunk and
mucous membranes. Lesions can expand and evolve over several days to assume the
classic annular "target" appearance with a dusky, necrotic center surrounded by a ring
of edema and pallor and an erythematous border.
One Step Further
Question: What is the treatment of choice in those who develop Erythema multiforme? -
Answer: In most cases of EM, supportive treatment is all that is necessary. Oral
antihistamines, steroids, and analgesics may be beneficial.
