Chapter 25: The Differential Diagnosis of Purpura

Sarah Nakib; Monica Rani

INTRODUCTION TO CHAPTER

Purpura is extravasation of red blood cells into the skin or mucous membrane. For this reason, purpuric lesions do not blanch on diascopy (pressing on the lesion with a glass slide or finger). The differential diagnosis for purpura is broad, but it can be quickly narrowed by classifying the lesions based on their morphology, as well as other clinical and laboratory findings.^1,2 The clinical descriptive terms for purpura are listed below, and their respective tables describing the differential diagnosis are referenced.

Petechiae: Flat lesions, macules ≤4 mm (Figure 25-1), typically initially bright red and then fade to a rust color (Tables 25-1 and 25-2).
Ecchymosis: Flat lesions, macules and/or patches, >5 mm (Figures 25-2 and 25-3), typically initially red or purple, but may fade to yellow, brown, or green (Table 25-3).
Palpable purpura: Elevated, round or oval, red or purple papules and/or plaques (Figure 25-4), sometimes barely palpable (Table 25-4).
Retiform purpura: Stellate or branching lesions, with angular or geometric borders (Figure 25-5). These are often palpable plaques, but can present as nonpalpable patches as well (Tables 25-5 and 25-6).

Table 25-1.Causes of petechiae (primary lesion is a macule ≤4 mm) with low platelets (<150,000/μL).

View Table||Download (.pdf)

Table 25-1. Causes of petechiae (primary lesion is a macule ≤4 mm) with low platelets (<150,000/μL).

Disease/Disorder

Clinical Features and Associations

Initial Diagnostic Evaluation

Low platelets (<150,000/μL)

Mucocutaneous bleeding (eg, epistaxis, increased bleeding with menses or minor cuts)

Splenomegaly and lymphadenopathy may be present

CBC with differential and peripheral smear; If anemic, check reticulocyte count, LDH, haptoglobin, and bilirubin

If hemolysis is present, check PTT, PT/INR, fibrinogen, D-dimer, Coombs, ANA. If inconclusive, consider bone marrow biopsy

Immune thrombocytopenia (ITP)³

F > M

Primary: Insidious onset

Secondary: Associated with underlying disease, for example, viral infections

Platelets <100, 000

Diagnosis of exclusion

Primary: Isolated decreased platelets

Secondary: May relate to viral process (can obtain serology for HIV, HCV, HBV, EBV, or PCR for parvovirus and CMV), H. pylori, ANA, pregnancy, APLA, or TSH

Thrombotic thrombocytopenic purpura (TTP)¹

Pentad: thrombocytopenia, hemolytic anemia, changes in mental status, fever, and renal dysfunction. Do not need all 5 for diagnosis

It may be idiopathic, familial, drug-induced, from pregnancy, HIV, autoimmune disease, or hematopoietic stem cell transplant

HUS: Thrombocytopenia, MAHA, and renal dysfunction; usually in children with prodrome of bloody diarrhea

Labs that can be observed: ↓ Platelets and MAHA, schistocytes on p.smear, ↑reticulocyte count, positive hemolysis labs (↑LDH, ↑indirect bilirubin, ↓haptoglobin), nlPTT & INR, ↑creatinine, ↓ADAMSTS13 (in idiopathic TTP)

Disseminated intravascular coagulation (DIC)⁴

Spectrum in hematologic abnormalities can have bleeding and/or thrombosis. May also have soft-tissue bleeding in muscle and joints

May be related to trauma, shock, infection, malignancy, and obstetric complication

↑PT/INR, ↑PTT, ↓ fibrinogen, positive fibrin degradation product/D-dimer, and hemolysis labs

Drug-induced¹

Petechiae, purpura due to drugs such as quinine, bactrim

Generally, isolated thrombocytopenia

Bone marrow suppression¹

Associated with aplastic anemia, MDS, drugs (eg, thiazides and antibiotics), alcohol, cirrhosis, myelofibrosis, granulomas from infections, hematologic, or solid malignancies

Peripheral smear may show pancytopenia, blasts, hypersegmented PMNs, leukoerythroblastic changes (teardrop cells, nucleated RBCs, immature WBCs)

ADAMTS13, a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13; ANA, antinuclear antibody; APLA, antiphospholipid antibody; bx, biopsy; CBC, Complete blood count; CMV, cytomegalovirus; dx, diagnosis; EBV, Epstein–Barr virus; F, female; H. pylori, Helicobacter pylori; HBV, hepatitis B virus; HCV, hepatitis C virus; HIV, human immunodeficiency virus; HUS, hemolytic uremic syndrome; LDH, lactate dehydrogenase; M, male; MAHA, microangiopathic hemolytic anemia; MDS, myelodysplastic syndrome; nRBC, red blood cells; p.smear, peripheral smear; PCR, polymerase chain reaction; PMNs, polymorphonuclear leukocytes; PT/INR, prothrombin time/international normalized ratio; PTT, partial thromboplastin time; TSH, thyroid stimulating hormone; WBC, white blood cells.

Table 25-2.Causes of petechiae (primary lesion is a macule ≤4 mm), with normal to high platelets (>150,000/μL).

View Table||Download (.pdf)

Table 25-2. Causes of petechiae (primary lesion is a macule ≤4 mm), with normal to high platelets (>150,000/μL).

Disease/Disorder

Clinical Features and Associations

Initial Diagnostic Evaluation

Platelet function disorder^5,6

Mucocutaneous bleeding

Look for splenomegaly and LAD

Labs: CBC with differential, peripheral smear, BUN, creatinine, LFTs, and platelet aggregation tests.

If suspect vWD or dysproteinemia, obtain vWF studies or SPEP/UPEP, respectively

Congenital or inherited⁵

vWD: usually AD

vWD: ↓ vW factor, ↓ vWF activity (measured by ristocetin co-factor assay) ↓ factor VIII, confirm with vWF multimer analysis

Acquired (eg, drug-induced, liver disease, uremia, dysproteinemia, acquired vWD)⁵

Associated medications include: ASA, NSAIDS, clopidogrel, ticlopidine

Acquired vWD may be associated with malignancy, autoimmune disease, hypothyroidism, or drugs

Liver disease may show abnormal LFTs or ↑PT/INR, ↑PTT

Uremia will show ↑ BUN

Dysproteinemias will show abnormalities on SPEP/UPEP

Thrombocytosis secondary to myelofibrosis⁶

Myelofibrosis maybe primary or secondary to other malignancy

Massive splenomegaly, ± fatigue, weight loss, and fever

Peripheral smear shows leukoerythroblastic changes and bone marrow biopsy shows a "dry tap" with severe fibrosis

No platelet abnormality

Pigmented purpuric eruptions, capillaritis

Clustered petechial hemorrhage, often with a background of yellow brown discoloration often on lower extremities. Most common in middle aged to older men

For example, Schamberg's disease, "cayenne pepper" appearance

No systemic findings

A biopsy maybe needed to differentiate lesions from vasculitis

Hypergammaglobulinemic purpura of Waldenstrom

Often in women, with recurrent crops of petechiae/purpura on lower extremities that burn/sting

Primary or secondary to autoimmune disease (eg, Sjogren's or SLE), RA, less likely hematologic malignancy

Hypergammaglobulinemia on SPEP

↑ titer of IgG or IgA RF (standard RF tests only detect IgM RF)

↑ESR

± positive ANA, anti-Ro, anti-La

Intravascular, local pressure, or trauma

Can be caused by valsava (eg, from vomiting or constipation) or blood pressure cuff

Can occur without an underlying lab abnormality

AD, autosomal dominant; ANA, anti-nuclear antibody; ASA, aspirin; BUN, blood urea nitrogen; CBC, complete blood count; ESR, erythrocyte sedimentation rate; LAD, lymphadenopathy; LFTs, liver function tests; NSAIDs, nonsteroidal anti-inflammatory drugs; p.smear, peripheral smear; PT/INR, prothrombin time/international normalized ratio; RA, rheumatoid arthritis; RF, rheumatoid factor; SLE, systemic lupus erythematosus; SPEP/UPEP, serum protein electrophoresis/urine protein electrophoresis; vWD, Von Willebrand disease; vWF, Von Willebrand factor.

Table 25-3.Causes of ecchymosis (primary lesion is a macule or patch ≥5 mm).

View Table||Download (.pdf)

Table 25-3. Causes of ecchymosis (primary lesion is a macule or patch ≥5 mm).

Disease/Disorder

Clinical Features and Associations

Initial Diagnostic Evaluation

Procoagulant defects¹

Susceptible to having deeper bleeding, into soft tissue

↑PT/INR, ±↑PTT

Anticoagulant

For example, warfarin

↑PT/INR

Liver disease

History of alcohol abuse, hepatitis, and primary liver disease

↑PT/INR, ↑PTT, abnormal LFTs

Vitamin K deficiency

State of malnutrition (eg, alcoholic), malabsorption (eg, from antibiotics), and liver disease

↑PT/INR

DIC

See Table 25-1

Platelet disorders

See Table 25-1

Decreased dermal support of vessels and minor trauma¹

Solar or senile purpura

Older age and sun damaged skin usually on forearms

None

Corticosteroid therapy (systemic and topical)

Cushing's syndrome stigmata (eg, central obesity, dorsocervical fat pad, moon facies)

Skin may reveal atrophy and telangiectasia

None

Scurvy (vitamin C deficiency)

Diet lacking in vitamin C

Perifollicular hemorrhage, corkscrew hairs, gingival bleeding, and tooth loss

↓Serum ascorbic acid deficiency and possibly other vitamins (eg, B12 and folate)

Systemic amyloidosis

All have hepatosplenomegaly, GI involvement (diarrhea, protein loss), and macroglossia

May also have cardiac, renal, and liver involvement. Periorbital waxy ecchymotic papules, purpura with minor trauma, and "pinch-purpura"

SPEP/UPEP and free light chain, ± bone marrow bx

CBC with differential, LFTs, BUN, creatinine, urinalysis, and EKG

Biopsy of abdominal subcutis fat pad reveals apple-green birefringence on Congo red stain

Consider genetic testing for hereditary form

Genetic disease with collagen or elastin defects

Ehler–Danlos Syndrome: stretchable skin and flexible joints, usually AD inheritance

Pseudoxanthoma elasticum: appearance of "plucked chicken skin" on neck

Genetic testing for specific mutations depending on the suspected condition

AD, autosomal dominant; BUN, blood urea nitrogen; bx, biopsy; CBC, complete blood count; EKG, electrocardiogram; GI, gastrointestinal; LFTs, liver function tests; PT/INR, prothrombin time/international normalized ratio; PTT, partial thromboplastin time; SPEP/UPEP, serum protein electrophoresis/urine protein electrophoresis.

Table 25-4.Causes of palpable purpura, inflammatory.

View Table||Download (.pdf)

Table 25-4. Causes of palpable purpura, inflammatory.

Disease/Disorder

Clinical Features and Associations

Initial Diagnostic Evaluation

Leukocytoclastic vasculitis, small and small-medium vessel vasculitis^7–9

Purpuric papules or plaques typically on distal legs or dependent areas

Skin biopsy for routine histology and another for DIF

Idiopathic (IgG, IgM, or IgA), secondary to drugs or infection

IgA lesions can appear targetoid

In addition to skin biopsies, careful review of medications, and recent/current infections

Henoch–Schönlein purpura

M > F. Usually age <20 years

Tetrad: purpura (universal), arthritis (82%), nephritis (40%), abdominal pain (63%), or gastrointestinal hemorrhage (33%)

May appear targetoid, on extensor areas and buttock

Extension to trunk/upper extremities can indicate renal involvement

Two skin biopsies should be done, one for routine histology and one for DIF

Obtain BUN/Cr, urinalysis

Urticarial vasculitis

Persistence of hive-like lesions >24 hours, often burn > itch. Can have concomitant systemic symptoms (eg, LAD, arthralgia, angioedema, and fever). Can be caused by drug (eg, ACE inhibitors, penicillin, and sulfonamides), autoimmune disease, hematologic or other malignancies, and infections

In addition to skin biopsies, the following lab findings may be helpful:

↓Complement (eg, CH50, C4, C3, Clq) may relate to a variety of systemic processes, for example, SLE, malignancy, and infection

Creatinine and UA. For suspected infection screen for HBV, HCV, and heterophile serology

For suspected autoimmune condition screen with autoantibody test

Mixed cryoglobulinemia (Type II and III)

Usually acral distribution

Weakness, livedo reticularis, leg ulcers, HSM, and Raynaud's phenomenon

Can also have glomerulonephritis and peripheral neuropathy

In addition to skin biopsies, the following labs may be helpful:

Cryoglobulins (proteins that precipitate from serum or plasma when cooled)

Type II: Sjogren's, SLE evaluation.

Type III: Hepatitis C RNA, ESR, and C4, RF

Rheumatic vasculitis (eg, RA, SLE, Sjogren's syndrome)

Digital ischemia, livedo reticularis, pericarditis, bowel ischemia, peripheral neuropathy

In addition to skin biopsies, the following lab findings may be helpful:

+ ANA and ↓complement (SLE)

+ RF, anti-CCP (RA)

+ ANA, RF, anti-Ro or La (Sjogren's)

Anti-neutrophilic cytoplasmic antibody (ANCA) associated

Wegener's granulomatosis

Usually young and middle-aged adults

Can have a nasal or oral (eg, sinusitis, saddle-nose deformity), pulmonary (eg, infiltrate, nodule, and cavity), or renal involvement (hematuria, RBC casts)

In addition to skin biopsies, +ANCA (90%), c-ANCA (anti-PR3)

Churg–Strauss

Usually age 30-40 years, with HLA-DRB4

Can also involve lungs (eg, asthma), peripheral nerves, heart, and kidneys

In addition to skin biopsies, CBC with differential, showing eosinophilia

+ANCA (50%), p-ANCA (anti-MPO), or c-ANCA (anti-PR3)

Microscopic polyangiitis

Can involve the kidney and lungs

In addition to skin biopsies, +ANCA (70%), p-ANCA (anti-MPO)

ANA, antinuclear antibody; anti-CCP, anticitrullinated protein; C, complement; c/p ANCA, cytoplasmic/perinuclear antineutrophil cytoplasmic antibodies; CBC, complete blood count; CH50, Complement H50; Cr, creatinine; DIF, Direct immunofluorescence; ESR, erythrocyte sedimentation rate; HBV, hepatitis B virus; HCV, hepatitis C virus; HSM, hepatosplenomegaly; LAD, lymphadenopathy; MPO, myeloperoxidase; PAS, Periodic acid-Schiff stain; PR 3, proteinase 3; RA, rheumatoid arthritis; RBC, red blood cells; RF, rheumatoid factor; RNA, ribonucleic acid; SLE, systemic lupus erythematosus; UA, urinalysis.

Table 25-5.Causes of retiform purpura with inflammation.

View Table||Download (.pdf)

Table 25-5. Causes of retiform purpura with inflammation.

Disease/Disorder

Clinical Features and Associations

Initial Diagnostic Evaluation

Rheumatic vasculitis (eg, RA and SLE)^1,13

See Table 25-4

PolyarteritisNodosa^1,13

M > F. Age ~ 50 years

Can have palpable subcutis nodules. Often multisystemic (eg, constitutional, renal, abdominal pain, livedo reticularis, peripheral neuropathies). Associated with HBV

In addition to skin biopsy, ↑ESR, CRP, WBC

HBsAg (positive in 30%)

ANCA vasculitides

See Table 25-4

Chilblains^1,13

Acral distribution

Occurs in cold, wet environment

History can be very suggestive. Skin biopsy may be helpful

ANCA, antineutrophil cytoplasmic antibodies; CRP, C-reactive protein; ESR, erythrocyte sedimentation rate; F, female; HBsAg, hepatitis B antigen; HBV, hepatitis B virus; M, male; RA, rheumatoid arthritis; SLE, systemic lupus erythematosus; WBC, white blood cell.

Table 25-6.Causes of retiform purpura, noninflammatory, and related to microocclusive disease.

View Table||Download (.pdf)

Table 25-6. Causes of retiform purpura, noninflammatory, and related to microocclusive disease.

Disease/Disorder

Clinical Features and Associations

Initial Diagnostic Evaluation

Platelet occlusion^1,4,6,10

In addition to a skin biopsy, the following lab findings may be helpful

Heparin necrosis (from heparin or low molecular weight heparin), heparin-induced thrombocytopenia (HIT), type II¹⁰

Often on the abdomen > extremities. Lesions may be distant sites or sites of heparin infusion or injection. Onset 4-10 days after treatment or <24 hours if drug used within 100 days. Postop highest risk. New venous or arterial thrombus (venous > arterial)

(Type I is with platelets >100,000 μL and benign course)

Platelets <100,000 μL or >50% drop from original with a + HIT antibody

Thrombocytosis, from myeloproliferative disorder⁶

See Table 25-2

Paroxysmal nocturnal hemoglobinuria (PNH)

Complement-mediated hemolytic anemia, hypercoagulability state, smooth muscle dystonia, cytopenia, aplastic anemia, MDS, evolution to AML, Budd–Chiari syndrome

CBC with differential and flow cytometry, showing ↓CD55 and CD59

Urine hemosiderosis

TTP

See Table 25-1

Cold-related gelling or agglutination (eg, cryoglobulinemia, cold agglutinins)¹

See Table 25-4. In addition, cryoglobulinemia type I (monoclonal) is associated with multiple myeloma and Waldenstrom's. Cold agglutinins in adults are associated with lymphoproliferative disease and in children infections (eg, Mycoplasma pneumonia, mononucleosis, and HIV)

Occlusion secondary to organism invading vessel¹

Invasive fungus, pseudomonas, strongyloidiasis, or leprosy in immunosuppressed patients or with history of travel to endemic areas

In addition to skin biopsy sent for routine histology, an additional biopsy may be sent for culture

Culture blood and other affected body fluids

Occlusion from systemic coaggulopathies^1,11–13

Inherited hypercoagulable states

Venous or arterial thrombi, miscarriages in women

↑ PT/INR, PTT

Protein C and S, antithrombin III, prothrombin 20210A, factor V Leiden mutation

Warfarin necrosis¹

Onset 1-10 days after exposure

Large irregular bullae with eventual necrosis on breasts, buttocks, thighs, and penile skin. More common in obese women or those with underlying hypercoagulopathy (eg, protein C or S or ATIII deficiency), may be postinfectious. Can have purpura fulminans

Nonspecific

Purpura fulminans¹

Branching palpable purpura leading to peripheral symmetrical gangrene. Can have sepsis with DIC (refer to Table 25-1) or be postinfectious

↑ PT/INR, PTT, D-dimer, fibrin degradation products

↓ Fibrinogen, platelets

Bacteria cultures may be positive. P.smear shows schistocytes

Antiphospholipid antibody or lupus anticoagulant^1,13

Acute and painful purpura, livedo reticularis and racemosa, and anetoderma. Usually age <40 years. Arterial thrombus, recurrent venous thrombi, or spontaneous abortions

Associated with SLE (40%-50% of SLE pts r-w), malignancy, infection, or drugs

+ Anticardiolipin or B2-glycoprotein antibodies

+ Lupus anticoagulant (↑PTT)

Occlusion from emboli¹

Cholesterol

M > F. Acral distribution

Arterial or cardiac catheter, prolonged anticoagulation, acute thrombolytic therapy, artherosclerosis, hypertension, and tobacco use are risk factors

Can be multisystemic

In addition to characteristic skin biopsy findings, CBC with differential, showing eosinophilia

Other lab abnormalities will depend on affected organ

Oxalate crystal

Acral distribution

Other than characteristic skin biopsy findings, may have hyperoxaluria

Endocarditis

Associated with IV drug use and prosthetic valves

Stigmata include Osler's nodes, Janeway lesions, and splinter hemorrhages

Blood cultures, EKG

Transthoracic and/or transesophageal echocardiogram

Occlusion from reticulocytes

Sickle cell disease

Can have symptoms of anemia from chronic hemolysis, infections with encapsulated organism from infracting spleen, osteomyelitis from infracting bone, and pain crisis

CBC shows anemia

Sickle-shaped RBCs or Howell-Jolly bodies on peripheral smear

Hb electrophoresis

Calciphylaxis¹⁴

F > M. Painful lesions leading to well-demarcated nonhealing ulcers. Can localize to extremities. Proximal distribution (eg, on trunk, buttock, and thighs) has poorer prognosis. Associated with chronic renal failure, diabetes, obesity, and poor nutrition

In addition to skin biopsy, the following lab findings are suggestive: hyperphosphatemia, elevated calcium-phosphate product (>70 mg/dL). Can also have ↑PTH, Ca, BUN, alkaline phosphatase

AML, acute myelogenous leukemia; APS, antiphospholipid syndrome; BUN, blood urea nitrogen;Ca, calcium; CBC, complete blood count; DIC, disseminated intercoagulopathy; F, female; Hb, hemoglobin; HIT, Heparin-induced thrombocytopenia; HIV, human immunodeficiency virus; HTN, hypertension; M, male; MDS, myelodysplastic syndrome; PT/INR, prothrombin time/international normalized ratio; PTH, parathyroid hormone; PTT, partial thromboplastin time; SLE, systemic lupus erythematosus.

Figure 25-1.

Petechiae. Bright red macules <4 mm on abdomen.

View Full Size||Download Slide (.ppt)

Figure 25-2.

Ecchymosis. Red, purpuric patches on arm in a 80-year-old male.

View Full Size||Download Slide (.ppt)

Figure 25-3.

Ecchymosis. Resolving purpura leaving red, purple, blue, and yellow patches.

View Full Size||Download Slide (.ppt)

Figure 25-4.

Palpable purpura. Multiple red papules on leg of a patient with Henoch–Schönlein purpura.

View Full Size||Download Slide (.ppt)

Figure 25-5.

Retiform purpura. Purpura on toes with retiform pattern on foot in a patient with cholesterol emboli.

View Full Size||Download Slide (.ppt)

APPROACH TO DIAGNOSIS

Listen

A flow chart for the differential diagnosis of purpura is in Figure 25-6. When considering the differential diagnosis of purpura, it is important to note that some of these conditions are life threatening and require prompt consultation of the appropriate specialty.

Figure 25-6.

Flow chart for the differential diagnosis of purpura.

View Full Size||Download Slide (.ppt)

EVALUATION

Listen

A careful history and review of underlying medical conditions, medications, and a complete physical examination can be crucial to the diagnosis.
Laboratory studies listed in the tables may assist with narrowing the differential diagnosis.
A skin biopsy is often necessary for further evaluation, at which time referral to a dermatologist is recommended. An optimal biopsy involves appropriate selection of the biopsy type, site, timing, and interpretation of results. At times, an additional biopsy needs to be done for direct immunofluorescence (DIF).
- Indications for skin biopsy: Palpable and retiform purpura should prompt a skin biopsy. Other indications include purpura whose cause cannot be determined by history, physical examination, and laboratory testing.
- Timing of biopsy: A new lesion less than 2 days old is ideal for biopsy. It is important to make note of the age of the lesion, as a disease process can appear different on histopathologic examination at various stages. For example, late leukocytoclastic vasculitis (LCV) and early microocclusive purpura can have similar histopathologic findings. It is important to let the pathologist reading the biopsy know how long the process has been present. Distinguishing between vasculitis and microocclusive disease is important because the two disorders require different treatments.
- Biopsy for direct immunofluorescence (DIF): In addition to the standard 4 mm punch biopsy, an additional biopsy should be sent for DIF (in special media) if leukocytoclastic vasculitis (LCV), small and small-medium vessel vasculitis is in the differential. This is particularly useful early in the process of LCV and can assist in the diagnosis of IgA-mediated diseases.
Findings on biopsy: Vasculitis is characterized by inflammation within vessel walls, often leading to extravasation of red blood cells and fibrin deposition in vessel walls. Vasculitis that manifests on the skin is limited to involvement of vessels found in the dermis and/or subcutis. The size of the affected vessels may give clues to the diagnosis.
- Small (eg, Henoch–Schonlein purpura, acute hemorrhagic edema of infancy, and urticarial vasculitis)
- Small-medium (eg, mixed cryoglobulinemia and rheumatic vasculitides)
- Medium (eg, polyarteritis nodosa)

DIF findings can give additional information, relating to the type of antibody visualized, for example, Henoch–Schonlein purpura and acute hemorrhagic edema of infancy show IgA deposition. The presence of granulomas also narrows the differential. Microgranulomas with an eosinophilic infiltrate are found in Churg–Strauss, necrotizing granulomatous inflammation of the vessel in Wegener's disease, and necrotizing pauci immune inflammation in microscopic polyangiitis. In chilblains, lymphocytic vasculitis with edema and thickening of dermal vessel wall is seen. Retiform purpura without inflammation generally reveals bland thrombi with no inflammation of vessel wall. Other retiform purpuras can have specific features, for example, cryoglobulinemia shows Periodic acid-Schiff stain positive hyaline intramural deposits, cholesterol emboli show needle-shaped clefts, and oxalate crystal emboli show yellow-gray birefringent crystals in the subcutis and vessel walls.¹ A skin biopsy for calciphylaxis shows calcification of small and medium vessels.

The online learning center at www.LangeClinicalDermatology.com has clinical self-assessment questions for this chapter.

REFERENCES

Listen

Piette WW. The differential diagnosis of purpura from a morphologic perspective. Adv Dermatol. 1994;9:3–24.
[PubMed: 8060741] .

Piette WW. Hematologic diseases. In: Goldsmith LA, Katz SI, Gilchrest BA, Paller AS, Leffell DJ, Wolf K, eds. Fitzpatrick's Dermatology in General Medicine. 8th ed. New York, NY: McGraw-Hill; 2012:1731–1740.

McCrae K. Immune thrombocytopenia: no longer 'idiopathic'. Cleve Clin J Med. 2011;78(6):358–373.
[PubMed: 21632906] .

Kitchens CS. Thrombocytopenia and thrombosis in disseminated intravascular coagulation (DIC). Hematology Am Soc Hematol Educ Program. 2009;240–246.
[PubMed: 200008204] .

Nichols WL, Hultin MB, James AH, et al. von Willebrand disease (VWD): evidence-based diagnosis and management guidelines, the National Heart, Lung, and Blood Institute (NHLBI) Expert Panel report (USA). Haemophilia. 2008;14(2):171–232.
[PubMed: 18315614] .

Tefferi A. Polycythemia vera and essential thrombocythemia: 2012 update on diagnosis, risk stratification, and management. Am J Hematol. 2012;87(3):285–293.
[PubMed: 22331582] .

Sunderkotter C, Sindrilara A. Clinical classification of vasculitis. Eur J Dermatol. 2006;16(2):114–124.
[PubMed: 16581560] .

Carlson AJ, Chen KR. Cutaneous vasculitis update: small vessel neutrophilic vasculitis syndromes. Am Dermatopathol. 2006;28(6):486–506.
[PubMed: 17122493] .

Gonzalez-Gay MA, Garcia-Porrua C, Salvarani C, Lo Scocco G, Pujol RM. Cutaneous vasculitis: a diagnostic approach. Clin Exp Rheumatol. 2003;21(6 suppl 32):S85–S88.
[PubMed: 14740432] .

10.

Ortel TL. Heparin-induced thrombocytopenia: when a low platelet count is a mandate for anticoagulation. Hematology Am Soc Hematol Educ Program. 2009;225–232.
[PubMed: 200008202] .

11.

Wysong A, Venkatesan P. An approach to the patient with retiform purpura. Dermatol Ther. 2011;24(2):151–172.
[PubMed: 21410606] .

12.

Weinstein S, Piette WW. Cutaneous manifestations of antiphospholipid antibody syndrome. Hematol Oncol Clin North Am. 2008;22(1):67–77, vi.
[PubMed: 18207066] .

13.

Khenifer S, Thomas L, Balme B, Dalle S. Livedoid vasculopathy: thrombotic or inflammatory disease? Clin Exp Dermatol. 2010;35(7):693–698.
[PubMed: 19874344] .

14.

Mathu RV, Shortland JR, Nahas AM. Calciphylaxis. Postgrad Med J. 2001;77(911):557–561.
[PubMed: 11524512] .

Pop-up div Successfully Displayed

This div only appears when the trigger link is hovered over. Otherwise it is hidden from view.

Chapter 25: The Differential Diagnosis of Purpura

Send Email

Citation

Jump to a Section

INTRODUCTION TO CHAPTER

Figure 25-1.

Figure 25-2.

Figure 25-3.

Figure 25-4.

Figure 25-5.

APPROACH TO DIAGNOSIS

Figure 25-6.

EVALUATION

REFERENCES

Pop-up div Successfully Displayed