DERMATOLOGIC DILEMMAS
| FREQUENTLY MISDIAGNOSED PROBLEMS REFERRED TO DERMATOLOGISTS —John R. T. Reeves, MD,
private practice, Augusta, GA
|
| Itching: notalgia paresthetica— localized intense itch (predominant symptom) on medial aspect of scapula; can also
tingle, burn, or have sensation of numbness; continuous or intermittent; may have pigmentation or rash; stimulation
of pinched nerve responsible for sensation of itch (paresthesia); nerve makes sharp turn near muscle; pinching of
nerve caused by muscle or by spinal problem (vertebral changes sufficient to cause pinching seen on x-ray in 60%
of patients); top of forearm—little or no rash; excoriations; unilateral or bilateral; also common area for neurodermatitis
(stress itching; neurotic excoriations from picking or digging); usually occurs in summer; brachioradial
summer prurigo; patients think problem from sun sensitivity; on x-ray, cervical spine abnormalities in 100%; serial
biopsies labeled for neurotransmitters showed decreased and damaged nerve fibers during summer that returned to
normal in autumn; possibly UV light triggered neuropeptide that damaged nerve; anogenital itching—rule out
other causes, eg, fungus, neurodermatitis, chafing, yeast; may have excoriation, and lichenification; if sensations of
burning, tingling, biting, crawling also present, nerve problem, not skin; x-ray showed degenerative changes; improved
with paravertebral injections of lidocaine with triamcinolone, proving neuritis; topical agents (eg, antipruritics)
not helpful and may cause side effects that exacerbate condition, eg, stabilizers (alcohols) in topical agents
irritate, causing contact dermatitis
|
| Dysesthesias: causalgia paresthetica—anterolateral thigh; itchy, tingly, ticklish feeling; nerve pinched due to spinal
problem, or fabric pressing on inguinal nerve may cause skin and nerve irritation (eg, tight jeans on truck drivers);
burning scalp syndrome, burning mouth syndrome, trigeminal neuralgia—dysesthesias from nerve sensation, not skin
problems; treatment by pain clinic or anesthesiologist with paravertebral injections of lidocaine and triamcinolone;
topical capsaicin, physical therapy, acupuncture, and tricyclic antidepressants (TCAs; eg, amitriptyline, nortriptyline)
used to treat neuralgias and neuritis; gabapentin, doxepin, and carbamazepine also used; TCAs probably
most successful; side effects include sleepiness with amitriptyline and agitation with nortriptyline
|
| Topical capsaicin: depletes nerve fiber of substance P (neurotransmitter); daily application over 2 to 3 wk stops
itching; burns during depletion process; one-third of patients can use successfully; use for postherpetic neuralgia,
diabetic neuropathy, postmastectomy pain syndrome, notalgia paresthetica, and brachioradial pruritus
|
| Antihistamines: have no antipruritic effect; data from 1960s show skin histamine levels elevated; recent studies
show no effect other than sedation (nonsedating antihistamines do not work); may use initially in atopic dermatitis
to help patient sleep while effective therapy (eg, steroids) being initiated; side effects—study with diphenhydramine
(Benadryl) and driving simulator demonstrated impaired coherence; performance impaired for ≥12 hr; contribute to
falls in elderly; use nonsedating antihistamines for histamine-mediated problems, eg, urticaria
|
| Topical steroids: no help for notalgia paresthetica, causalgias, or brachioradial pruritus; steroids anti-inflammatory,
not antipruritic; do work for atopic dermatitis (inflammatory condition); topical steroids work, depending on
strength; use aggressively; aura of dangerousness unwarranted because if used properly, side effects rarely seen;
study— fluticasone cleared chronic atopic dermatitis; participants then switched to 2-day weekly regimen instead
of 7 days/wk, vs placebo 2 days/wk; those on placebo started to relapse, while those on fluticasone did much better,
with no skin atrophy and normal serum cortisol levels; clobetasol (much more potent than fluticasone) may cause
atrophy, depending on where applied; atrophy temporary; potency— study found patients had no real understanding
of potency, but worried about side effects; compliance— patients with psoriasis reported high compliance rates,
but microchip in cap of tube indicated compliance much lower; in childhood eczema trial, compliance one-third;
variable compliance may compromise accuracy of double-blind studies; may represent real world
|
| Seborrheic dermatitis: “little old ladies with itchy heads”; cradle cap (thick scaly substance); dandruff shampoo
helpful or nongreasy liquid topical agents (clobetasol or betamethasone); use daily until cleared up; because steroid
will not penetrate keratin plate, patients with thick scaly area need 25% urea cream or lotion (eg, heel creams); rub
into scalp and sleep with shower cap overnight (each week, on night before professional shampoo at beauty parlor);
use steroid between shampoos
|
| Nails: onycholysis—lifting up or separation of distal nail plate from nail bed; nail bed holds nail down while growing
nail moves across it; attachment loosened by moisture (hands in water frequently) and with age; nail becomes
less attached and strength of attachment weakens; longer nails have more leverage, causing more microseparation
and letting water in; bacteria and yeast colonize area; nail cannot reattach once lifted; treatment—decrease water
exposure; miconazole liquid or tolnaftate (not much yeast coverage); put one drop in cuticle or under nail edge bid;
use until new cuticle formed or nail grows in (3 mo) or until nail edge grows in; exostosis of bone—white area under
nail; hard, not painful; must be ground down by orthopedic surgeon; mucoid cysts—trenches or depressions in
nail; usually one digit, eg, distal interphalangeal joint (DIP) of finger or toe; 2 variants, channel to joint space of
DIP joint (attached) or ball of mucus with pseudo-wall (not attached); mucofibroma that exudes jelly-like material
(synovial product); treatment—repeated incision and drainage by patient; intralesional steroids; destruction by
freezing, electrodesiccation and curettage, or orthopedic excision with ligation; tuberous sclerosis—periungual fibromas
cutaneous sign; dominantly inherited genodermatosis; often asymptomatic, but large fibroma in brain may
cause seizure
|
| COMMON SKIN DISORDERS —Julie A. Letsinger, MD, Assistant Clinical Professor of Dermatology, University
of California, San Francisco, School of Medicine, and Associate Director, UCSF Psoriasis Treatment Center, San
Francisco
|
| Impetigo: Staphylococcus aureus causes 50% to 70% of cases; remainder group A streptococci or Staphylococcus
and Streptococcus combination; types—classic erosion with honey-colored crust (bullous impetigo) always due to S
aureus with exotoxin; most commonly on head and neck, and perioral and perinasal areas; extremities next most
common; treatment—antistaphylococcal antibiotic and topical mupirocin; if localized, mupirocin alone; soak off
crusts with aluminum acetate (Domeboro) solution; first-line treatment β-lactamase-resistant antibiotic for 7 days;
20% to 40% of adults carriers (nasal); for recurrent episodes, consider mupirocin in nares twice daily first week of
month on ongoing basis to eradicate
|
| Methicillin-resistant Staphylococcus aureus (MRSA): for persistent disease or recurrent infection, consider culture
and sensitivity; treatment—doxycycline or minocycline, trimethoprim–sulfamethoxazole (TMP–SMZ; eg,
Septra), clindamycin; rarely use intravenous (IV) vancomycin or linezolid
|
| Tinea: in groin, treat with ketoconazole or terbinafine for 2 to 4 wk
|
| Candida: moist beefy plaques with pustules; may look dry; if moist, use drying agent (eg, Domeboro solution); nystatin
or imidazoles; keep skin folds apart if recurrent; keep dry by separating skin folds with gauze; weight loss
|
| Onychomycosis: discoloration, subungual hyperkeratosis, and crumbling nails; most common cause Trichophyton
rubrum; treatment—may be mainly cosmetic problem or painful; can be portal of entry for bacterial infection, so
treatment indicated in patients with, eg, diabetes, peripheral neuropathy, recurrent cellulitis; confirm diagnosis
with culture or special nail stains because other conditions in differential diagnosis may look identical, and treatments
have side effects;
|
 | Treatment: griseofulvin and ketoconazole no longer used; terbinafine (Lamisil)—first-line treatment 250 mg daily for 3
to 4 mo; can be hepatotoxic; expensive; 2005 study showed continuous therapy better than pulsed; itraconazole
(Sporanox)—pulsed for 1 wk/mo for 3 to 4 mo; has more drug interactions and broader spectrum (covers molds);
“black box” warning for congestive heart failure; hepatotoxic; expensive; efficacy—terbinafine thought to have 70%
mycologic cure (negative culture at end of study); percentage lower for complete cure (nail looks normal and culture
negative); only 40% to 55% cure at ≈18 mo; with itraconazole, ≈25% of patients cured at 18 mo
|
| Tinea capitis: scales, some alopecia; fluorescence shows black dots (broken hairs from fungus); positive KOH test
less sensitive, culture better but takes 1 mo; treatment—start while waiting for culture; griseofulvin gold standard;
examine siblings and parents and treat if suspicious; terbinafine and fluconazole also effective; kerion—
inflammatory hypersensitivity reaction to T capitis; resembles bacterial infection, eg, oozing, boggy, crusting; treat
with griseofulvin; consider prednisone to calm inflammation and reduce scarring
|
| Lyme disease: caused by spirochete, Borrelia burgdorferi; spread by deer tick; first stage rash, erythema migrans
seen 3 to 30 days after tick bite; most patients unaware of bite; in later stages, patient may develop heart block, arthritis,
or chronic neurologic symptoms; treat promptly with doxycycline or amoxicillin; screening enzyme-linked
immunosorbent assay (ELISA) indicated, but do not wait for results; diethyltoluamide (DEET) best for prophylaxis
|
| Scabies: itchy lesions between fingers or polymorphic rash from neck down; worse at night; itchy papules on genitalia
in men considered scabies until proven otherwise; head and neck involved in infants, immunosuppressed, and
elderly; see mites under microscope (typically 12 mites on adult); treatment—educate patient about treating self,
contacts, clothing, and linens; permethrin first-line therapy; category B in pregnancy; repeat in 1 wk; ivermectin
pills for crusted scabies or institutional outbreak; lindane has potential for neurotoxicity; sulfur safe but malodorous
(used for 3 consecutive days)
|
| Body lice: seen in homeless people and in crowded settings; look for lice in seams of clothing (discard clothing);
treatment—pyrethrin (eg, Rid) or permethrin (eg, Nix, Elimite) first-line treatment for head or pubic area;
malathion also used; check eyelashes and treat with petroleum jelly if lice found
|
| Basal cell cancer (BCC): pearly papules or scaly patches; raised threadlike shiny margin; seen in older patients
with fair skin and excessive sun exposure; head and neck area site of predilection; number one malignancy in
United States; rarely metastasizes but invades locally; diagnose with punch or shave biopsy; treatment—if on
nose, margin control surgery (Mohs’ surgery); standard excision for other areas; curettage and desiccation for torso
lesions with less aggressive histology; consider radiation in older patient; 5% imiquimod cream (Aldara) for superficial
BCC on torso
|
| Actinic keratoses: 1% to 2% evolve into squamous cell carcinoma (SCC); treatment—liquid nitrogen, 5-fluorouracil
topically, imiquimod cream; educate patient about skin irritation
|
| Squamous cell carcinoma: 0.5% to 5% metastasize; areas likely to metastasize include lip (≈13%) and scar
(≈30%); lower-risk lesions on back of hand, forehead, areas of cumulative sun exposure; higher-risk lesions in areas
of radiation therapy, burn scars, ulcer or draining sinus, and in immunosuppressed patients, eg, transplant patient
(what usually kills them; stress sun protection); treatment—surgical excision
|
| Pigmented lesions: melanoma; mnemonic—ABCDE, asymmetric, borders irregular, color, diameter, evolution;
risk factors—personal or family history; genetics, many nevi, fair skin, red or blond hair, green or blue eyes, sun
exposure; tanning booths linked to melanoma (base tan does not protect and may increase risk); indicators of worse
outcome include older patient, male sex, axial lesion; thickness of lesion correlates most strongly with outcome; ulceration
of primary lesion next strongest correlation; for tumors >1 mm, sentinel lymph node biopsy recommended
(becomes most important prognostic factor); treatment—complete excision
|
| Inflammatory disorders: eczema, psoriasis, lichen planus; red itchy scaly skin; perform KOH test to rule out
tinea; atopic dermatitis—in infants, cheeks, wrists, ankles; in children, antecubital fossa, popliteal fossa, eyelids; in
adults, chronic hand eczema; affects 15% to 20% of US children <5 yr of age; 70% grow out of it by age 15 yr;
treatment—skin care; topical steroids first line; calcineurin inhibitors—tacrolimus (eg, Protopic) and pimecrolimus
(Elidel); have black-box warning for lymphoma and skin malignancy; officially second-line therapy; use intermittently
in immunocompetent patients >2 yr of age to avoid use of steroids in sensitive areas, eg, eyelids; other
treatments—phototherapy and immunosuppressive drugs for more severe disease
|
| Psoriasis: well demarcated plaques on elbows and knees; thick white scales; 2% to 3% of population affected; 10%
to 30% develop psoriatic arthritis ≈10 yr after onset of skin lesions; predilection for scalp, nails, extensors, gluteal
cleft; usually spares face; treatment—3 levels, topical, phototherapy, internal medicine; based on extent of disease
(5% of body surface area cutoff between mild-localized and severe); topical therapy—topical steroids alone (work
fast but have side effects) or in combination with, eg, calcipotriene (Dovonex), which has slow onset of action;
combination therapy allows tapering of steroids and maintenance with calcipotriene, tar, or tazarotene;
phototherapy—UVB (broad and narrow band), psoralen-UVA (PUVA; linked to SCC and melanoma); oral
drugs—acitretin (Soriatane), methotrexate, cyclosporine, biologic drugs; goal to decrease side effects
|
| Lichen planus: diagnose by 5 “P”s, ie, pruritic, purple, planar, polygonal, papules; Wickham striae, lacy white reticular
pattern on top of lesions, especially in buccal mucosa; etiology unknown, but possibly associated with hepatitis
C; most patients clear in first year; 1- to 2-mo course of systemic steroids usually cures without recurrence;
light therapy used for recurrence
|
Suggested Reading
Krejei-Manwaring J et al: Stealth monitoring of adherence to topical medication: adherence is very poor in children
with atopic dermatitis. J Am Acad Dermatol 56:211, 2007; Leon J et al: An attempt to formulate an evidence
based strategy in the management of moderate-to-severe psoriasis: a review of the efficacy and safety of biologics
and prebiologic options. Expert Opin Pharmacother 8:617, 2007; Rizzo M et al: Treatment of mucous cysts of the
fingers, review of 134 cases with minimum 2 year follow-up evaluation. J Hand Surg 28:519, 2003; Van Der Meer
JB et al: The management of moderate to severe atopic dermatitis in adults with topical fluticasone propionate. The
Netherlands Adult Dermatitis Study Group. Br J Dermatol 140:1114, 1999; Warshaw EM et al:Pulse vs continuous
terbinafine for onychomycosis: a randomized, double-blind, controlled trial. J Am Acad Dermatol 53:578, 2005;
Weiler JM et al: Effects of fexofenadine, diphenhydramine, and alcohol on driving performance, A randomized,
placebo-controlled trial in the Iowa driving simulator. Ann Int Med 132:354, 2000.
Educational Objectives
| The goal of this program is to improve the management of skin conditions. After hearing and assimilating this program,
the clinician will be better able to:
|
| 1. Describe and identify common as well as unusual causes of itching.
|
| 2. Discuss the appropriate use of topical steroids, antihistamines, tricyclic antidepressants, and other agents in the
treatment of pruritic skin conditions.
|
| 3. Diagnose and treat onycholysis and other disorders of the nails.
|
| 4. Manage patients with common skin conditions such as tinea capitis, scabies, impetigo, and psoriasis.
|
| 5. Review appropriate treatment of basal cell carcinoma, squamous cell carcinoma, and pigmented lesions such
as nevi and melanomas.
|
Faculty Disclosure
In adherence to ACCME Standards for Commercial Support, Audio-Digest requires all faculty members to disclose
relevant financial relationships within the past 12 months that might create any personal conflicts of interest. Any
identified conflicts were resolved to ensure that this educational activity promotes quality in health care and not a proprietary
business or commercial interest. For this program, the following has been disclosed: Dr. Letsinger has been
involved in research with Abbott, Astellas, Genentech, and Warner Chilcott.
Acknowledgements
Dr. Reeves spoke at the Medical Masters Class series of lectures sponsored by the North Staffordshire Postgraduate
Education Organization, held in Newcastle-under-Lyme, UK, on June 26, 2007. Dr. Letsinger spoke at Family Medicine
Board Review Course, sponsored by the University of California, San Francisco, School of Medicine on July 12,
2007. The Audio-Digest Foundation thanks the speakers and the sponsors for their cooperation in the production of
this program
|
