Dermatology Flashcards Preview

Renal/Skeletal > Dermatology > Flashcards

Flashcards in Dermatology Deck (134)
Loading flashcards...

Dermatitis herpetiformis

Blistering disease of skin due to immune-complex deposition in papillary dermis
- More common in N. Europeans
- Age of onset= 2nd-3rd decade
- 20% of patients have celiac disease, over 90% have GI findings on endoscopy

Clinical findings:
- Herpetiform (grouped) vesicles symmetrically distributed on knees, elbows, forearms, buttock, scalp (rare)
- May have crusted lesions with non-specific pruritis (like atopic dermatitis, scabies, drug eruption)

1. Circulating antibodies including IgA to:
- Gliadin (antigen= wheat protein)
- Reticulum
- Smooth muscle endomysium
- Tissue transglutaminase
2. Deposition of immune-complexes in mucosa of:
- Small intestine (malabsorption symptoms)
- Papillary dermis of skin (blistering)

1. Antigens in skin:
- epidermal transglutaminase
- antigen-antibody complex deposits in skin
- NON-circulating
2. Skin biopsy
- lesional skin forhisto: subepidermal bulla with neutrophils
- Peri-lesional skin for immunofluorescence study (granular IgA deposition)
3. Tissue transglutaminase Ab in serum
4. DQ2/DQ8 HLA testing
- high prevalence in normal population (low positive predictive value)
- High negative predictive value

- Gluten-free diet (slow improvement)
- Dapsone (anti-neutrophilic for skin symptoms)
- Monitor for enteropathy-associated T-cell lymphoma (due to constant antigenic stimulation); DQ2 homozygotes at high risk


Porphyria Cutanea Tarda

PCT= most common cause of all porphyria
2 forms:

1. Sporadic (80-90%):
- Decreased activity of uroporphyrinogen decarboxylase in liver secondary to underlying liver disease

2. Familial (10-20%):
- Decreased activity of uroporphyrinogen decarboxylase in all tissues, including erythrocytes
** Most gene carriers asymptomatic until sufficient liver damage occurs

- Male, over 40, alcohol
- EtOH, estrogen, hexachlorobenzene, iron overload
- Iron overload (in PCT)-_> decreased uroporphyrinogen decarboxylase activity

- Uroporphyrinogen decarboxylase deficiency--> accumulation of photoactive molecules that absorb visible violet light
- Photo-excited porphyrins in skin--> oxidative damage--> photosensitivity reactions

Clinical manifestations:
- Photosensitivity
- Blisters and skin fragility on sun-exposed sites, dorsa of hands and feet, face
- Shiny skin
- Hypertrichosis (Hairy face)

Associated disease:
- Hep B, C
- Beta-thal
- Hemachromatosis
- Hepatocellular carinoma
- EtOH

- Skin biopsy (pauci-inflammatory subepidermal bulla= epidermal lifting with no inflammation, necrosis)
- Fresh urine (pink to orange-red with Wood's lamp)
- Porphyrin analysis (24 hr urine, plasma, stool)

- Phlebotomy (decrease Fe overload)
- Hydroxycholorquine (anti-malarial)
- Block sun exposure


Panniculitis: Erythema nodosum

Occurs at any age, generally young, healthy adult women
- Tender erythematous nodular eruption (pre-tibial)
- May be accompanied by arthralgia (ankles, knees, wrists)
- Septal panniculitis

Hypersensitivity reaction associated with other diseases, but 1/2 idiopathic
- Infections (strep, viral, fungal)
- Drugs (OCP, sulfonamides, penicillin)

Usually self-limited

- Oral corticosteroids, SSKI (super-saturated potassium iodide)


Panniculitis: Necrobiosis Lipoidica

Unknown pathogenesis

- Plaques with violaceous brown border, atrophic center
- Histiocytes, lymphocytes, plasma cell around blood vessels

- 0.3% diabetic patients have NLD
- 22-65% with NLD have diabetes
- Avg age= 30 years

No effective treatment:
- intralesional steroids
- doxycycline (anti-granulomatous)


Leukocytoclastic vasculitis

ex: Henoch-Scholein Purpura, Behcet's disease

Immune-complex deposition mediated destruction of post-capillary venules

Skin= most common involved organ
- Purpuric papules (palpable purpura)
- Urticarial papules, purpuric macules, vesicles/bullae, pustules, ulcers
- Distal areas, classically bilateral legs

Skin lesions my have systemic signs/symptoms:
- Fever, joint pain, abdominal pain, bloody urine
- may indicate internal organ involvement

Manifestation of diseases/meds:
- Connective tissue diseases
- Viral, bacterial infections
- Malignancies, lymphomas/leukemias

50% cases are idiopathic

Workup: CBC, BUN, Cr, LFT, ESR, RF, ANA, Antistreptolysin, cryocrit, serum protein electrophoresis, hepatitis serologies

- Neutrophils
- Extravasated RBCs
- Fibrin deposition around vessels

NSAIDs, antihistamines
Antibiotics (Dapsone)


Henoch-Shonlein purpura

Form of LCV:
- viral or bacteria-induced
- frequently involves joint, GI tract, kidneys
- Children 3-10 years of age
- Immune complex consists of IgA (vs IgG)

High risk of ESRD:
- Serial urinalysis to detect kidney involvement (hematuria)


Polyarteritis nodosa

Necrotizing neutrophilic vasculitis of small to med-sized vessels with predilection for GI tract, liver, kidneys, skin

- Fevers, arthralgia, myalgia, abdominal pain, mononeuritis multiplex, renovascular HTN, microaneurysms, NO pulmonary involvment
- Skin involved in 50% cases, livedo reticularis, plaques, nodules, ulcerations
- 10% skin-limited

Associated with:
- Hep B (7%)
- Hep C, HIV, strep, CMV, parvo B19
- Most cases idiopathic

- ulceration
- dispigmentation: retiform purpura on legs- worrisome vasculitis/vasculopathy (non-blanching)
- nodules


Antiphospholipid syndrome

APL syndrome seen in women (80%) ~42 years old

1-5% young, health people have Antiphospholipid antibodies without consequences
- Occur with other conditions; IgM are present at low levels (infections, cancer, drugs, hemodialysis)

Group of heterogeneous antibodies:
1. Lupus anticoagulant
- dilute Russell's viper venom time (PTT prolongation)
- Corrects with addition of excess phospholipid/platelets
2. Anticardiolipin
- ELISA on cardiolipin-coated platelet in presence of bovine serum
3. anti-beta2 glycoprotein antibodies (phospholipid binding proteins)
- ELISA for coated platelets

Diagnostic criteria:
- Anticardiolipin or lupus anticoagulant antibodies 2+ times, 6 weeks apart
- Clinical: vascular thrombosis +/- pregnancy complications

Clinical classfication:
- Primary: no associated disease (90%)
- Secondary: SLE, RA

1. Thrombosis of large and small vessels of both arteries and veins of any organs
- deep venous thrombosis= most common
- arterial thrombosis= strokes and TIA
2. Complications
- pulmonary emboli
- emboli of vegetation of cardiac valves
- gynecologic: miscarriages usually during fetal period, premature delivery
3. Acute involvement of small vessels= similar to HUS, TTP
- results in loss of organ function
- Catastrophic antiphospholipid syndrome

Cutaneous manifestations:
- superficial thrombophlebitis
- ulcers
- livedo reticularis
- acrocyanosis

- High intensity warfarin therapy (INR: 3.1-4.0)
- Plasmapheresis and/or IVIG for refractory and “catastrophic” cases


Differential diagnosis for ulcers

malignant neoplasms
vascular insufficiency
diabetic ulcers
pyoderma gangrenosum
factitial ulcers

Work-up: Skin biopsy, swab culture, tissue culture


Pyoderma gangrenosum

Diagnosis of exclusion
Chronic suppurative inflammation resulting in tissue destruction
Size and depth of the ulcers vary

Associated diseases:
- inflammatory bowel disease, especially ulcerative colitis
- IgA monoclonal gammopathy
- leukemia



Almost exclusively seen in patients with end-stage renal disease
- Progressive calcification of small arteries result in ischemic necrosis of the skin
- No effective treatment
- High mortality rate-60 to 80% due to sepsis

Histo: fractured blood vessel lining= calcification

Treatment: difficult (already sick with dialysis


Systemic Amyloidosis

Underlying causes: Multiple myeloma and Waldenstrom’s macroglobulinemia
- Amyloid consists of immunoglobulin light chains
- Deposition may occur in any organs

Skin and mucosal lesions
- deposits in vessels result in purpuras (leaky vessels)
- pink translucent papules and nodules

Classic sign: carpal tunnel syndrome and purpura (e.g. raccoon eye sign, pinch purpura)

1. Skin biopsy
- amorphous pink homogeneous material
- stains with Congo red, which turns bright green fluorescence upon polarization
2. Rectal mucosal biopsy
3. Abdominal subcutaneous fat aspirate


Eruptive Xanthoma

Usually widespread eruption of yellowish papules
- High triglcyeride level due to lipoprotein lipase deficiency, less often seen in patients with diabetes and patients on retinoids (accutaine, isotretinoins)
- Skin biopsy shows lipid laden foamy histiocytes and interstitial deposition
- Complications include pancreatitis and atherosclerosis


Mycosis fungoides

The most common form of T-cell lymphoma of the skin (NOT fungus!)

Clinical stages include patch, plaque, nodular, tumor, and erythrodermic stages
- Unlike psoriasis, which has flares and remission, this is continuous

Most patients have patches for a lifetime and a few will have progressive disease resulting in death

- Neoplastic proliferation of T-helper cells (CD4+)
- Sézary cells (CD4+ cells with convoluted nuclei) are found in the blood in the erythrodermic stages

Treatment will depend on the clinical manifestation, but the disease is incurable


Kaposi's sarcoma

Virally induced (HHV8) vascular hyperplasia rather than a neoplasia
- Metastatic vs multifocal
- AIDS defining disease (HHV8 infection accompanied by immune suppression to manifest)

In immunocompromised individuals, it can be found in the skin and in any visceral organs, especially:
- GI bleeding, pulmonary hemorrhage, lymph nodes

4 types:
1. Epidemic AIDS related
- Usually related to low CD 4 count
2. Classic/ sporadic
- Elderly Mediterranean/ Eastern European men
- Seen in lower extremity
- NOT immune compromised
3. Immunocompromised
- Transplantation
- Sirolimus (mTOR inhibitor- can cause OR treat in transplant patients), anti-VEGF, antiangiogenesis
4. Endemic/ African
- Indolent or aggressive
- Lymphadenopathic form in children

Patch, plaque, nodular, exophytic, infiltrative, lymphadenopathic

- Spindle cell proliferation of endothelial cells with slit-like vascular spaces, extravasated RBCs
- May be more lymphatic in origin than vascular by staining patterns


Sweet's syndrome

Paraneoplastic syndrome (remote effect from primary neoplasm- paraneoplastic pemphigus, necrolytic migratory erythema, erythema gyratum repens)

- Acute febrile neutrophilic dermatosis
Characterized by:
- tender edematous erythematous papules and plaques
- accompanied by fever and peripheral neutrophilia

Skin biopsy:
- band like infiltrate of neutrophils in the dermis with edema of the papillary dermis
- no leukocytoclasis of neutrophils (no dust)

Associated with:
- acute myeloid leukemia
- drugs-GMCSF (neutrophil maturation)
- pregnancy
- inflammatory bowel diseases
- upper respiratory infections

- Corticosteroids (treat infection/ malignancy first)


Acanthosis Nigracans

Velvety hyperpigmentation usually on the neck
- Most frequent association is obesity
- Rarely, association with adenocarcinoma of the GI tract has been described


Fixed drug eruption

Recurrent hyperpigmented patches with repeated use of drug
- Can also see central necrosis in patch--> bullae

Tx: stop offending agent

Common offenders: barbiturates, tetracyclines, pseudoephedrine, nsaids/naproxen, erythromycin, sulfonamides, phenolpthalein


Morbiliform drug eruption

Generalized rash maculopapular with no malaise
- Reaction to drugs started in past 2-3 weeks (unless previously exposed, could be 24-48 hours)

Tx: identify and stop offending agent, topical steroids, +/- prednisone taper

Workup: Monitor for evolution, mucosal involvement, onset ( avg =3 weeks)

* CAN treat patient with same drug again (non life-threatening reaction); sensitize patient to drug in ICU



Drug eruption + Eosinophilia and Systemic symptoms
- Severe drug rash

- widespread morbilliform eruption
- oral mucosa (usually one site only)
- avg time to onset 21 days

Eosinophilia- ~50% cases

Systemic Involvement-
- elevated LFTS,
- renal insufficiency,
- hematologic abnormalities,
- fever

HHV6 association
Common offenders: allopurinol, dapsone, phenytoin


Stevens Johnson Syndrome

Rash: erythematous macules coalescing into vesicles denuding

Pathogenesis: extensive keratinocyte death via apoptosis

Mucosal Involvement: 3 sites

Body surface area Involvement %
SJS: < 10% ;
10% < SJS/TEN 30% involvement

Treatment: Derm Consult.
- Identify and stop offending agent.
- 95% cases due to drug (NSAIDS, Antibiotics (sulfas), Anticonvulsants)
- No good treatment;
- IVIg vs IV corticosteroids early

Supportive care. Transfer to burn unit. Opthalmology consult.

Prognosis: high mortality rate: 5% (SJS), 35% (TEN)

- AIDS- 1000x fold increase
- Slow acetylators
- Immunocompromised
- Brain tumor patients on anti-epileptics with radiation therapy
**screen for HLA-B*1502 in Asian patients to be prescribed carbamazepine


Acne inducers

Even stupid drugs like hormones induce acne vulgaris:
- EGFR inhibitors,
- steroids,
- dilantin,
- lithium,
- halogens,
- INH,
- Vitamins


Embryological development of skin

- Epidermis forms as single layer in first weeks of embryogenesis
- Neural crest elements (melanocytes) migrate to the epidermis (8th week)
- Adnexa (hair, eccrine glands) form around 12th week as invaginations from the epidermis into the dermis
- Sebaceous and apocrine glands sprout from follicular epithelium


Normal skin structure

Epidermis: stratum basale, spinosum, granulosum, lucidum, corneum
- keratinocytes (adnexae)
- melanocytes
- Langerhans cells
- Merkel cells (sensory)

- fibroblasts (elastic fibers)
- Bone- marrow derived cells: Mast cells, B/T lymphocytes
- Vessels (endo and pericytes)
- Neural tissue

Subcutaneous fat


Langerhans cells

APC (antigen-presenting cells) seen in epidermis)
- Characteristic Birbeck granules seen by electron microscopy


Types of epidermal inflammation

Angiocentric: around blood vessels
- Urticaria, necrotizing vasculitis

Spongiotic: increased fluid between keratinocytes (edema)
- Allergic contact dermatitis

Interface: Inflammation between epidermis and dermis
- Lupus, contact dermatitis

Vesiculo-bullous: blistering between epidermis and dermis (lifting)
- Pemphigus

Panniculitis: inflammation of subcutaneous fat
- Erythema nodosum


Responses to skin injury: proliferation

Hyperplasia= Acanthosis
- Psoriasis

Dysplasia= atypical cell

Neoplasia: benign and malignant
1. Benign Epidermal:
- Seborrheic keratosis, Verruca
2. Pre-malignant Epidermal: Actinic keratosis
3. Malignant Epidermal:
- Squamous cell carcinoma, Basal cell carcinoma
4. Benign Melanocytic: Melanocytic nevus
5. “Pre-malignant” Melanocytic:
- Dysplastic/Atypical melanocytic nevus
6. Malignant Melanocytic: Melanoma


Response to skin injury: storage/deposition

Solar elastosis: dense clumpy deposition of elastic fibers due to chronic sun damage

Secondary amyloidosis: deposition of amyloid in skin

Gout: deposition of birefringent uric acid crystals in dermis surrounded by granulomatous inflammation



Angiocentric skin changes
Often young adults
- Transient, lasts < 24 hrs
- Non-purpuric wheals: Edematous, erythematous papule or plaque
- Intensely pruritic (itchy)
- Angioedema (deep)
- Chronic forms: Urticarial vasculitis, Underlying disease

- Dermatographism
Type I hypersensitivity reaction
- Immunologic (IgE-mediated): Mast cell degranulation, Release of histamine, prostaglandins
- Non-immunologic: Mechanical (dermatographism), Temperature

- Mast cells degranulate: release Histamine, prostaglandins, cytokines
--> Vascular dilation, Dermal edema, Endothelial activation
- E-selectin/CLA binding
- Angiocentric inflammation: Lymphocytes, neutrophils, eosinophils
- No epidermal changes


Necrotizing vasculitis

Angiocentric skin changes
Seen on Lower extremities
- Palpable purpura= Red macules and papules with dot-like hemorrhage
- Diascopy

Limited to skin or systemic
- Drugs, infection, connective tissue disease, underlying malignancy (Idiopathic in 50%)

Henoch-Schönlein Purpura: seen after strep, viral illness (hematuria, abdominal pain, vasculitis mediated by IgA)

- Infiltrate of neutrophils with fragmentation (nuclear “dust”)
- Neutrophils chew thru fibrin in vessel walls and lumen (fibrinoid necrosis)
- Hemorrhage due to vessel wall destruction (extravasation--> no blanching)
- Positive DIF (direct immunofluorescence)