Purpura refers to purple or red-brown spots, bruises, or bleeding under the skin. Purpura occurs when small blood vessels leak blood into the skin or mucous membranes. There are several different causes of purpura, including benign causes like medications, infections, and blood disorders like leukemia. So while purpura can sometimes indicate leukemia, it has many other potential causes as well.
What is Purpura?
Purpura occurs when small blood vessels called capillaries rupture and leak blood into the surrounding tissue. This causes the characteristic purple, red, or brown spots or bruises on the skin, mucous membranes, or organs.
Some key facts about purpura:
- Caused by bleeding under the skin from broken capillaries
- Leads to purple, red, or brown spots or bruises on the skin or mucous membranes
- Size of purpura spots can vary from pinpoint to several centimeters
- Does not blanch (go away) when pressure is applied
- Often seen on lower legs, forearms, trunk, mucous membranes
Types of Purpura
There are several different ways to classify the types of purpura:
By cause:
- Non-thrombocytopenic purpura – normal platelet levels
- Thrombocytopenic purpura – low platelet levels
By duration:
- Acute purpura – sudden onset, lasts days to weeks
- Chronic purpura – persists longer than 6 weeks
By vessel type:
- Capillaritis – capillaries affected
- Vasculitis – larger vessels affected
Some common specific types of purpura include:
- Senile purpura – chronic purpura in elderly patients, often on forearms, hands
- Exercise-induced purpura – acute purpura after strenuous exercise, mainly on legs
- Henoch-Schönlein purpura – IgA-mediated vasculitis, common cause of acute purpura in children
- Primary immune thrombocytopenia – autoimmune low platelets, can cause purpura
Identifying the specific type of purpura can help determine the underlying cause.
What Causes Purpura?
There are several potential causes and risk factors for developing purpura:
Medications
Many medications can cause purpura as a side effect, including:
- Anticoagulants like heparin or warfarin
- Antiplatelet drugs like aspirin, clopidogrel
- Corticosteroids like prednisone
- Antibiotics like penicillin, sulfonamides
- NSAIDs like ibuprofen
These drugs affect platelet function or blood clotting, increasing the risk of capillary leakage.
Infections
Infections can also trigger vasculitis and capillaritis that lead to purpura:
- Bacterial infections like streptococcus, staphylococcus
- Viral infections like hepatitis C, HIV, herpes simplex
- Fungal infections like aspergillosis
- Parasitic infections like malaria
Infections provoke inflammation and immune responses that damage blood vessels.
Inflammatory Conditions
Inflammatory disorders can cause immune-mediated blood vessel damage:
- Autoimmune disorders like lupus, rheumatoid arthritis
- Inflammatory bowel disease like Crohn’s or ulcerative colitis
- Vasculitis syndromes like Henoch-Schönlein purpura
Blood Disorders
Hematologic conditions that affect platelets and coagulation often cause purpura:
- Thrombocytopenia – low platelet count
- Disseminated intravascular coagulation (DIC) – widespread clotting
- Congenital coagulation disorders like hemophilia
- Leukemia and myeloproliferative neoplasms
These make patients prone to bleeding and capillary leakage.
Senility
Fragile capillaries in elderly patients often cause chronic senile purpura.
Other Causes
Less common causes include:
- Blood vessel fragility disorders like scurvy, amyloidosis
- Platelet function disorders like Bernard-Soulier syndrome
- Solid cancers like lung, pancreatic, ovarian cancer
- Diabetes mellitus
- Kidney disease
- Liver disease like cirrhosis
Identifying the underlying cause is key to proper treatment.
Is Purpura Related to Leukemia?
Leukemia and related blood cancers are one potential cause of purpura. Here’s an overview of the link between purpura and leukemia:
- Acute leukemias cause thrombocytopenia (low platelets) which can lead to purpura.
- Chronic leukemias less often cause severe thrombocytopenia or purpura.
- Acute promyelocytic leukemia specifically causes DIC with bleeding.
- Leukemia infiltration into skin can also damage vessels causing purpura.
- Chemotherapy for leukemia can sometimes cause thrombocytopenic purpura.
So purpura can be associated with both acute and chronic leukemias, but is more typical of acute conditions. Key types of leukemia that can lead to purpura:
Acute Myeloid Leukemia (AML)
– AML causes cytopenias including thrombocytopenia in over 60% of patients.
– 1/3 of patients have platelet counts under 20,000 at diagnosis.
– This severe thrombocytopenia contributes to bleeding risk including purpura.
Acute Promyelocytic Leukemia (APL)
– APL is a subtype of AML with severe DIC in over 90% of cases.
– Widespread clotting consumes platelets and clotting factors.
– Causes extensive purpura, mucosal bleeding, internal bleeding.
Acute Lymphoblastic Leukemia (ALL)
– ALL can lead to thrombocytopenia and anemia.
– Up to 20% of adults have platelet counts under 20,000.
– Low counts increase risk of purpura and bleeding.
Chronic Myeloid Leukemia (CML)
– CML less often causes severe thrombocytopenia than acute leukemias.
– Around 5-10% of patients have platelet counts under 100,000.
– Mild thrombocytopenia can still increase purpura risk.
So in summary, both acute and chronic leukemias can be associated with increased risk of purpura, but this is more common and severe with acute conditions, especially APL.
How is Purpura Diagnosed?
Diagnosing the cause of purpura involves evaluating:
Medical History
Important details include:
- Medications
- Recent infections
- Family history of bleeding or autoimmune disorders
- History of leukemia, lymphoma, or myeloproliferative neoplasms
Physical Exam
Looking for:
- Rash characteristics – location, pattern, color
- Other skin lesions suggestive of vasculitis
- Enlarged lymph nodes, spleen
- Joint swelling or deformities
Blood Tests
To evaluate:
- Complete blood count – low platelets or hematocrit?
- Coagulation testing – elevated D-dimer or PT/PTT?
- Electrolytes, creatinine – kidney function
- Liver enzymes – liver function
- ESR, CRP – inflammation markers
- Blood cultures – infection
Biopsy
May include:
- Skin biopsy of purpura rash
- Bone marrow biopsy to rule out leukemia
Imaging
Such as:
- CT scan to check for organ bleeding or lymph node enlargement
- Ultrasound to assess spleen size or look for joint damage
Putting together the results of the history, exam, and testing can determine if leukemia or another condition is the cause.
How is Purpura Treated?
Treatment depends on the underlying cause:
Medication-Related
May involve:
- Stopping suspected causative medication
- Avoiding drugs that impair platelet function
- Short course of corticosteroids if severe
Infections
Requires:
- Treating underlying infection with appropriate antibiotics or antivirals
- Corticosteroids if vasculitis component
Inflammatory Disorders
Includes:
- Treating underlying condition – autoimmune disorder, IBD, etc.
- Immunosuppressants like corticosteroids, cyclophosphamide
- IVIG for severe cases
Thrombocytopenia
May need:
- Platelet transfusions if counts very low
- Medications to increase platelet production
- Plasma exchange for TTP
- Immunosuppressants for ITP
Leukemia
Requires:
- Chemotherapy for acute leukemias
- Targeted therapy for chronic leukemias
- Platelet transfusions as needed
Anticoagulation
If bleeding risk is high, may use:
- Supportive care – rest, compression
- Antifibrinolytics like tranexamic acid
- Recombinant factor concentrates
So treatment focuses on resolving the underlying cause while providing supportive care.
What is the Prognosis for Purpura?
The prognosis for purpura depends on:
- Cause – medications often resolve quickly, while serious conditions like leukemia have a poorer prognosis.
- Severity – mild purpura often resolves well, while extensive bleeding indicates poorer prognosis.
- Patient factors like age, comorbidities, treatment response.
Some key prognostic factors:
Medication-Related
Usually resolves within days to weeks of stopping medication, excellent prognosis.
Infections
Progresses with treatment of underlying infection. Resolves within weeks if treated promptly.
Inflammatory Disorders
Variable, depends on severity of vasculitis and response to immunosuppression. Many improve over weeks to months.
Thrombocytopenia
Depends on etiology. ITP often improves but relapses. TTP has over 80% survival with prompt plasma exchange.
Leukemia
Relies on response to chemotherapy and hematopoietic cell transplant if eligible. Prognosis depends on leukemia type and risk factors.
Conclusion
In summary, purpura can have many causes including medications, infections, inflammatory conditions, thrombocytopenia, and leukemia. While not all purpura indicates leukemia, acute leukemias often cause bleeding including purpura due to low platelets. Determining if leukemia is the underlying cause relies on clinical examination and diagnostic testing. Treatment focuses on resolving the primary condition while providing supportive care. Prognosis depends greatly on the specific etiology. Purpura from medications or infection generally carries a good prognosis, while purpura from hematologic malignancies like leukemia has a more guarded outlook.