37-year-old South American Male Case Study Mini-Series

The purpose of this mini-series is to get in the mind of a treating physician when a patient such as this presents to the clinic or the ED in this case. The first part of this series is the introduction of the case with case history and initial lab testing. Please don’t hesitate to leave comments on what you think the diagnosis is and what other confirmatory tests need to be done if any as well as what treatment should consist of. This is mean’t to stimulate a discussion and there are no wrong answers. I am in no way a physician or at that level or have that education. I am a student with a passion for molecular diagnostics and creating these cases is a good way for me to practice real life scenarios through careful and diligent research as well as help others who think the same way. This case is no way real and all lab values are made up to the best of my knowledge. If anything is incorrect please do not hesitate to email me or  leave a comment.

CASE:

A 37-year-old South American male presented to his annual physical with his primary care physician with general fatigue, decreased appetite and weight loss over the past three weeks. The patient mentioned to his physician that he has had multiple nosebleeds throughout the last few weeks, an occurrence of multiple a week. The patients past medical history is unremarkable. No family history of bleeding tendencies. He is not taking any prescription medication and denies use of recreational drugs and only social use of alcohol. His physician ordered a CBC and a prothrombin time/activated partial thromboplastin time (PT/aPTT). Results are in table 1.

Two days later the patient presented to the emergency room with fever and heavy fatigue, he explained to the attending that it has been hard to do anything the last few days, and has been bed-ridden. Physical exam revealed bilateral bruising on the upper arms and forearms with purpura and petechiae. The attending physician ordered a full coagulation panel, platelet function tests (Ristocetin cofactor assay), bleeding time test for vWD, and full CBC with peripheral blood smear analysis. Results are summarized in table 2.

Later that evening the patient developed a high fever, and back/flank pain and was moved to the ICU. Blood cultures, CRP and a procalcitonin was ordered, results are in table 3.

Positive cultures for Staphylococcus aureus were found after 48-96 hours and the patient was started on a course of vancomycin and monitored closely.

Patient results indicated he was pancytopenic with a hemoglobin of 9.7 g/dL (Ref. 13.5-18.0 g/dL) and RBC count of 3.7×10^3/uL (Ref. 4.20-6.00×10^6 uL) with severe thrombocytopenia at 37×10^3/uL (Ref. 150-450×10^3/uL).

Initial coagulation results revealed significantly elevated PT and aPTT. The bleeding time test along with the results from the RCO indicate platelet dysfunction or acquired inhibition of platelets by accelerated destruction. Platelet aggregation studies were normal. RCO studies indicate factor VIII inhibition or consumption.

The peripheral blood smear confirmed leukopenia and thrombocytopenia and revealed abnormal promyelocytes with abundant azurophilic granulation and multiple auer rods in bundles. RBC morphology showed schistocytes and fragmented cells.

The attending followed up by ordering a complete fibrinogen, D-dimer and a plasminogen panel. Results are in table 4.

The significantly elevated D-dimer, elevation in t-PA and u-PA in combination with the significant decrease in fibrinogen, and plasminogen levels indicates primary hyperfibrinolysis.

The attending sent a blood sample to the Blood Bank laboratory and asked for units of packed red cells, platelets, and fresh frozen plasma (FFP) to be transfused. With the additional blood components, the patient was able to regain control over the thrombocytopenia, hemoglobin, fibrinogen and coagulation factor levels.

A bone marrow aspirate was ordered including cytology, cytochemistry, immunophenotyping, FISH (Fluorescence in situ hybridization), cytogenetics (chromosomal analysis and FISH) and RT-PCR for PML/RARA quantification of transcripts. The attending started the patient on all-trans retinoic acid (ATRA) as induction therapy.

FISH revealed the PML-RARA fusion gene present which was later quantified and confirmed by RT-PCR. PCR sequencing revealed a bcr-3 PML-breakpoint. Chromosomal analysis of the bone marrow identified a t(15;17) classic translocation. Cytochemistry revealed intensely positive reacting cells to myeloperoxidase and Sudan black B. Immunophenotyping results are in table 5.

Table 1:

RBC: 4.10×10^6/uL             4.20-6.00×10^6/uL          

HGB: 12.9 g/dL                    13.5-18.0 g/dL        

HCT: 38.7%                          40-54%

MCV: 88 fL                            80-100 fL

MCH: 33.2 pg                        26-34 pg

MCHC: 32.3 g/dL                  32-36 g/dL

RDW: 13.5%                         11.5-14.5%

RETIC: 0.8%                          0.5-2.5%

NRBC: 0/100 WBC               0

WBC: 6.3×10^3/uL              3.6-10.6×10^3/uL

NEUT: 3.6×10^3/uL             1.7-7.5×10^3/uL

LYMPH: 1.9×10^3/uL          1.0-3.2×10^3/uL

MONO: 0.7×10^3/uL           0.1-1.3×10^3/uL

EO: 0.1×10^3/uL                  0.0-0.3×10^3/uL

BASO: 0                                 0.0-0.2×10^3/uL

PLT: 111×10^3/uL              150-450×10^3/uL

MPV: 7.3 fL                           7.0-12.0 fL

 

PT: 21 seconds                    11-14 seconds

aPTT: 37 seconds               25-35 seconds

Table 2:

RBC: 3.7×10^3/uL              4.20-6.00×10^3/uL

HGB: 9.7 g/dL                     13.5-18.0 g/dL                    

HCT: 28.9%                          40-54%

MCV: 71 fL                            80-100 fL

MCH: 31.8 pg                       26-34 pg

MCHC: 33.1 g/dL                 32-36 g/dL

RDW: 15.1%                        11.5-14.5%

RETIC: 2.3%                         0.5-2.5%

NRBC: 0/100 WBC               0

WBC: 2.5×10^3/uL             3.6-10.6×10^3/uL

NEUT: 1.3×10^3/uL           1.7-7.5×10^3/uL    

LYMPH: 0.7×10^3/uL         1.0-3.2×10^3/uL

MONO: 0.3×10^3/uL          0.1-1.3×10^3/uL

EO: 0.1×10^3/uL                 0.0-0.2×10^3/uL

BASO: 0.1×10^3/uL            0.0-0.3×10^3/uL

PLT: 37×10^3/uL               150-450×10^3/uL

MPV: 19.3 fL                       7.0-12.0 fL

 

Myeloblasts: 7%                  0%

Promyelocytes: 54%         0%

Myelocytes: 3%                    0%

Metamyelocytes: 5%           0%

Bands: 0%                             0%

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PT: 33 seconds                   11-14 seconds

aPTT: 63 seconds              25-35 seconds

BT: 13 minutes                   1-9 minutes

RCO: 30%                              50-150%

Platelet aggregation studies: Normal

Table 3:

Blood Cultures: POS Staph aureus          NEG

Procalcitonin: 0.25 ng/mL                        <0.15 ng/mL

CRP: 23 mg/L                                                0-10 mg/L

Table 4:

Fibrinogen: 67 mg/dL

Plasminogen: Reduced

a2-Antiplasmin: Reduced

t-PA: Elevated

u-PA: Elevated

D-Dimer: >19,000 ng/mL    

Table 5:

CD2                NEG

CD4                NEG

CD13              POS

CD14              NEG

CD16              NEG

CD19              NEG

CD33              POS

CD34              NEG

CD45              POS

CD56              NEG

CD64              POS

CD117            POS

HLA-DR         NEG

 

-Caleb

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Disseminated Intravascular Coagulation

Disseminated intravascular coagulation (DIC) is a generalized activation of homeostasis secondary to a systemic disease. There are multiple different diseases that can activate different homeostatic factors that can contribute to DIC. Conditions such as physical trauma and endothelial cell damage exposing tissue factor that finds its way into circulation; or being exposed to tissue factor through vasodilation from hypovolemic shock, malignant hypertension or even heat stroke. There is a long list of secondary conditions that can set off an array of events that can lead to DIC. DIC involves all aspects of homeostasis; the vascular intima, platelets, leukocytes, coagulation, coagulation regulation, and fibrinolysis. DIC is often called a consumptive coagulopathy as it is consuming platelets at a rapid rate that form fibrin microthrombin that partially occlude small vessels. These thrombi that form are small and ineffective so systemic hemorrhage occurs which is often the first sign of DIC or one of the first signs prevalent.

To understand the pathophysiology of DIC its important to have a handle on normal primary and secondary homeostasis in the body. Normal physiological coagulation initiation begins on tissue-bearing cells such as fibroblasts and the subendothelial cells. This is called the extrinsic tenase complex which is composed of tissue factor, factor VIIa, and calcium. When tissue factor that is released from damaged subendothelial cells comes into contact with coagulation factor VII it activates it and that complex produces factors Xa, and IX and miniscual amounts of thrombin. There is also a minute amount of factor VIIa that is circulating in the blood that is resistant to breakdown from tissue factor pathway inhibitor (TFPI) and can bind to tissue factor to start coagulation. The initiation phase and the small amount of thrombin produced starts the initial fibrin formation by splitting the fibrinogen peptides A and B from fibrinogen and activates platelets through cleavage of protease activated receptors PAR-1 and Par-4, cofactors, factor Va released from the platelet alpha granules, factor VIIIa to be released by vWF, and procoagulants such as factor IX to be used further in propagation.

Coagulation Cascade

Propagation is where more than 95% of the thrombin is generated and occurs on the surface of the platelets. Initiation attracts a copious amount of platelets to adhere to the site of the injury from both the low-level thrombin released and exposed collagen. These initial platelets are sometimes called COAT-platelets or platelets partially activated by collagen and thrombin. The COAT-platelets have a higher level of procoagulant activity than platelets activated by collagen alone. These platelets also provide a surface for the intrinsic and prothrombinase tenases to form. Factors Va and VIIIa that were activated by thrombin in initiation bind to platelet surfaces and become receptors for factors IXa and Xa. Factor IXa binds to VIIIa and forms in the intrinsic complex. The intrinsic complex then activates factor Xa, which binds to factor Va that forms the prothrombinase complex. The prothrombinase complex activates prothrombin which generates thrombin. Thrombin activates factor XIII to stabilize the fibrin clot by covalently cross-linking the fibrin polymers initiated by the extrinsic tenase, binds to its cofactor thrombomodulin to activate the protein C pathway and also activates thrombin activatable fibrinolysis inhibitor (TAFI) to inhibit fibrinolysis to protect the formation of the fibrin clot.

Platelets as mentioned above have an important role in homeostasis. Platelet activation occurs once the platelet binds to collagen or the vWF that is present on the surface of the damaged endothelial cells. Adhesion occurs through the integrin GP IX V platelet receptor. Upon binding they secrete their primary granules that secretes molecules such as ADP, epinephrine, serotonin, and calcium. Calcium and other molecules like ADP activate phospholipase A2 through GCPRs otherwise known as 7 transmembrane receptors. Thomboxane A2 (TXA2) is then synthesized by thromboxane synthase in multitude of events. TXA2 generates secondary messengers DAG and IP3. DAG helps mediate actin contraction for shape conformational changes and IP3 binds to the IP3 receptors in the dense tubular system that opens calcium channels to allow release of more calcium. The activation of DAG and IP3 induces a conformational change that activates the fibrinogen receptor GP IIb/IIIa which allows adjacent platelets to aggregate and form the initial platelet plug. Platelets are also important in that they allow a surface for propagation of coagulation to occur.

With a basic background of primary and secondary homeostasis it will now be easier to understand what actually occurs during DIC. Triggering events may activate coagulation at any point in its pathway. Circulating thrombin that is released activates platelets, activates coagulation proteins that have positive feedback loops within the coagulation cascade and catalyzes fibrin formation. The fibrinolytic system enzymes such as plasminogen and TPA may become active subsequent to fibrin clot formation. Monocytes may also be induced to released tissue factor caused by inflammation in DIC. Normally thrombin cleaves fibrinogen creating fibrin monomers which spontaneously polymerize to from this insoluble gel which is strengthened through factor XIII. In DIC, a high percentage of the fibrin monomers fail to polymerize and just circulate in plasma as soluble monomers. These circulating monomers coat platelets and coagulation proteins which doesn’t allow any binding creating an anticoagulant effect. Plasmin, which is the activated form of plasminogen is a part of the fibrinolytic system. In normal homeostasis plasmin only cleaves the solid fibrin clot formed. Although in DIC, plasmin circulates in the plasma and degrades all forms of fibrin. It is because of this that fibrin degradation products, otherwise known as D-dimers become detectable in the plasma in concentrations commonly exceeding 20,000 ng/mL. The normal range for the D-dimer is 0-240 ng/mL. At the same time coagulation pathway control is lost as protein C, protein S, and anti-thrombin are consumed by the plasmin. Plasmin also digests factors V, VIII, IX, and XI. The platelets become enmeshed within the fibrin monomers and become exposed to thrombin which triggers platelet further platelet activation and consumption. Plasmin can also trigger complement which causes hemolysis and the kinin system which triggers inflammation and hypotension and as an end result shock.

It is important to diagnose DIC early and as a physician be aware of the early signs. A lot of times the symptoms of DIC are masked by the underlying disease and may be chronic or acute. The initial laboratory testing includes a platelet count, blood film examination, PT, aPTT, D-dimer and fibrinogen assay. The PT time is usually >14 seconds (Ref. 11-14) aPTT is usually >35 seconds (Ref. 25-35). These time intervals clue in that there is a coagulation issue as the PT tests the function of the extrinsic pathway and the aPTT tests the function of the intrinsic pathway. The platelet count is lower than 150,000 uL (Ref. 150,000-450,000 uL). The D-dimer as noted previously is significantly elevated. Although a D-dimer alone can’t diagnose DIC because a D-dimer is elevated in other conditions such as inflammation, pulmonary embolism and deep vein thrombosis. The fibrinogen levels may drop below 220 mg/dL (Ref. 220-498), but that provides little diagnostic information because in a lot of cases the fibrinogen level may not rise or may become elevated because of the level of inflammation occurring while the patient is in DIC. A peripheral blood smear confirms thrombocytopenia as well as the presence of schistocytes. Schistocytes are broken red blood cells because the microvessel walls are occluded they get shredded while passing through the blood vessels. Although not one test result can rule in DIC or rule it out, a panel of specialized tests can help in the diagnosis. It’s important to get the whole picture.

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Treatment of chronic DIC is to diagnose and treat the underlying condition. This may include surgery, anti-inflammatory agents, or antibiotics to stabilize homeostasis. Supportive therapy to maintain fluid and electrolyte balance is important in the treatment of chronic DIC. In acute DIC where there is multi organ failure from microthrombi and hemorrhagic bleeding therapies are targeted at slowing the clotting process and to replace the consumed coagulation factors and proteins. Unfractionated heparin is commonly used for its anti-thrombotic properties. Normally the aPTT is used to monitor heparin therapy, but in the case of DIC other assays must be used so it’s important to pay close attention to the patient when administering heparin as it can aggravate bleeding tendencies. Physicians may also order fresh frozen plasma (FFP), platelets, and red cell transfusions as needed. FFP will replace the coagulation factors and proteins. The platelets will correct for the thrombocytopenia and the red cells are transfused because of the resulting anemia. Cryoprecipitate can also be administered to replace the low levels of fibrinogen. A physician may use an INR to figure out the best way to treat the DIC as well as monitor the therapy. The INR or international normalized ratio is a way of standardizing the PT results, regardless of test methods and where the testing occurred. A normal INR should be between 2-3. An INR too low puts the patient as risk for blood clots, on the contrary and INR too high puts the patient as too high of a risk for bleeding. As the underlying condition begins to stabilize the DIC will begin to subside and patient will slowly recover.

There will be more covered about DIC and how it relates to different leukemias and solid tumor cancers. This article provides an overview and how it affects normal homeostasis.

-Caleb