Cutaneous Conundrums, Dermatologic Disguises

Case 1:

A nonhealing ulcer recently developedin a painful facial rash that hadworsened over several months. The44-year-old patient is a heavy drinkerwith a history of elevated liver functionlevels. She has had numerousunprotected sexual contacts over theyearsAn oral cephalosporin has hadno effect on the facial eruption.The patient denies the use of othermedications.Which of the conditions in thedifferential is the likely cause?

A.

Bacterial infection secondary toseborrhea.

B.

Squamous cell carcinoma.

C.

Bacterial infection secondaryto rosacea.

D.

Deep fungal infection.

E.

Pyoderma gangrenosum.

F.

Factitial disorder.Which course of action do youpursue?

G.

Perform a bacterial culture.

H.

Perform a fungal culture.

I.

Determine the patient's HIVstatus.

J.

Obtain a hepatitis panel.

K.

Perform a skin biopsy.

Case 2:

Neither oral terbinafine nor oral itraconazole resolved the white patch on a62-year-old woman's fingernail. The condition, which first arose 3 monthsago, causes slight, intermittent tenderness. The patient is otherwise healthyand takes no medications.What is the likely cause of this condition?

A.

Thyroid disease.

B.

Diabetes mellitus.

C.

Onychomycosis.

D.

Candida

onycholysis.

E.

Psoriasis.To confirm your suspected diagnosis, you . . .

F.

Perform thyroid function tests.

G.

Obtain a serum glucose level.

H.

Perform a potassium hydroxide evaluation.

I.

Perform a fungal culture.

J.

Perform a bacterial culture.

Case 1:

Pyoderma gangrenosum

,

E,

was a pathergic response to this patient'sunderlying sebopsoriasis. Shewas predisposed to this reactive processby hepatitis C; serologic testingwas positive for anti-hepatitis C virusantibody,

J.

A skin biopsy,

K,

whichruled out a destructive skin cancer,deep infection, and factitial disease,supported the clinical impression.Prednisone and anti-hepatitis Cvirus therapy were prescribed. Thepatient's condition improved steadilyover several months.All of the diagnostic options arereasonable; however, bacterial infectionsgenerally are much more acutethan this patient's disease. Deep fungalinfections are indolent but rarelyoccur in an immunocompetent host.Rapid ulceration with associated painis not typical of squamous cell carcinoma.Factitial disease is a considerationin this setting.

Case 2:

Distal onycholysis,

D,

usuallyis caused by

Candida

species, whichgrew in the fungal culture,

I,

of aspecimen obtained from this patient'sfingernail. Most patients acquire theinfection from excessive exposure towater; housecleaning and dishwashingare frequent causes. Although oralantifungal agents usually are effective,this patient's repetitive hand washingproduced a favorable environment forreinoculation. The addition of a topicaldrying agent (4% thymol) to an oralantifungal agent, such as itraconazole,fluconazole, or terbinafine, allows the nail to grow out reattached to the nail bed.Diabetes increases the risk of initial episodes and recurrences of onycholysisand onychomycosis. However, the involvement of only a single nail makesdiabetes-as well as thyroid disease-unlikely. The pitting and oil-drop appearanceof psoriasis-affected nails is not seen in this patient. The transverse ridgingof the nail is attributable to trauma to the cuticle, not to the disease process.The thickened nail and subungual debris often seen in onychomycosisare absent here.

Case 3:

A 37-year-old woman presents with her third episode inseveral months of a slightly tender rash on her trunk.She states that the eruption always looks the same, arisesin the same location, and disappears after 2 to 3 weeks.The patient takes vitamins daily, antihistamines for seasonalallergies, and sulfa antibiotics for occasional urinary tractinfections.What is the likely cause of the eruption?

A.

Pityriasis rosea.

B.

Tinea corporis.

C.

Psoriasis.

D.

Fixed drug reaction.

E.

Contact dermatitis.What therapy do you offer the patient?

F.

A corticosteroid cream.

G.

An antifungal cream.

H.

Calcipotriene cream.

I.

Change the antihistamine.

J.

Change the antibiotic.

Case 3:

This rash is characteristic of a

fixed drug reaction,

D:

circular, erythematous lesions that reappear in thesame location after rechallenge with the same medication.The culprit here was the sulfa antibiotic, which was discontinued;a nonsulfa agent was substituted,

J,

and noadditional eruptions occurred.Pityriasis rosea, tinea corporis, and psoriasis lesionsdo not come and go and are usually pruritic, not tender.Contact dermatitis, which can reappear after reexposureto the causative agent, typically is pruritic.

Case 4:

A 12-year-old girl presents with a 3-month history of an itchy, bumpy rashon her legs; initially, it was thought to be eczema. When the outbreak did notrespond to a potent topical corticosteroid, the patient was given ciclopiroxcream, but the antifungal offered no relief.What condition is responsible for the lesions?

A.

Psoriasis.

B.

Contact dermatitis.

C.

Nummular eczema.

D.

Impetigo.

E.

Dermatophyte infection.The potassium hydroxide (KOH) evaluation is negative; your nextstep is to . . .

F.

Perform a fungal culture.

G.

Perform a bacterial culture.

H.

Perform a skin biopsy.

I.

Initiate a trial of an oral antibacterial antibiotic.

J.

Initiate a trial of prednisone in a tapering dosage.

K.

Initiate a trial of an oral antifungal antibiotic.

Case 4:

A deep

dermatophyte infection,

E

, of a hair follicle, or Majocchigranuloma, produces an infectiousfolliculitis that is similar to tinea capitis.Unfortunately, a KOH evaluationis often negative; a skin biopsy,

H,

isneeded to confirm the diagnosis. Thiscondition usually arises as a result ofocclusion, trauma or, as in this patient,shaving. Topical therapy is oftenineffective, and systemic antifungaltreatment is warranted.Contact dermatitis generally does not last for 3 months. Both nummulareczema and psoriasis are more scaly and respond to topical corticosteroids.Impetigo features crusting and is self-limited.

Case 5:

A 48-year-old man presented with apainful rash on his neck of a few days'duration. Despite the patient's denialof trauma or bite, the initial impressionwas that of a brown recluse spiderbite. A second group of vesiclesin a similar distribution arose shortlyafter the first. Levofloxacin and prednisonehave been given for 2 days,but the rash remains.What do you suspect?

A.

Herpes simplex.

B.

Herpes zoster.

C.

Brown recluse spider bite that isunresponsive to the prescribedagents.

D.

Staphylococcal infection.

E.

Contact dermatitis.You prescribe which of the following?

F.

An antiviral agent to cover herpes simplex.

G.

An antiviral agent to cover herpes zoster.

H.

Dapsone.

I.

An oral cephalosporin.

J.

Another tapered course of prednisone.

Case 5:

The appearance of a secondgroup of vesicles on an erythematousbase confirmed the clinical suspicionof

herpes zoster

,

B;

a solitary group ofvesicles on an erythematous base canbe either herpes simplex or herpeszoster.Typically, contact dermatitis ispruritic, not painful. Staphylococcalinfections can be vesicular when impetiginous,but the vesicles are morefragile and more pruritic. Brownrecluse spider bites are necrotic, notvesicular.This patient's eruption resolvedafter the antiviral agent famciclovir,G, was given. Valacyclovir also offers good bioavailability and activity againstherpes zoster and is another option in this setting.

Case 6:

Three days ago, a 26-year-old womanwas given levofloxacin for a mildlypruritic eruption on her posteriorthigh. The rash had appeared a fewdays earlier after she had been in ahot tub. She seeks further evaluationbecause her symptoms have notabated.What are you looking at here?

A.

Partially treated hot tub folliculitis.

B.

Yeast folliculitis.

C.

Contact dermatitis.

D.

Impetigo.

E.

Herpes simplex.Your approach is to prescribe . . .

F.

Tetracycline.

G.

A topical corticosteroid cream.

H.

Penicillin.

I.

A topical allylamine antifungalcream.

J.

A short tapered course ofprednisone.

Case 6:

The distribution of the rash suggests contact dermatitis, C, causedby something the patient sat on. A topical corticosteroid cream, G, resolvedthe eruption.Hot tub folliculitis presents with painful papules and pustules on theinvolved areas. The follicular papules and pustules of yeast folliculitis are morepruritic. Unlike the eruption seen on this patient, impetigo features crustedareas. The grouped vesicles on an erythematous base that characterize herpessimplex were absent here.