Page 535 - Clinical Hematology_ Theory _ Procedures ( PDFDrive )

CHAPTER 26 ■ Disorders of Primary Hemostasis and Thrombosis Vasculature and Platelets 519

T e MPNs are interre ate c ona he ato oietic ste ce ay be generate by extra e u ary, robab y s enic he a-

isor ers characterize by excessive ro i eration o one or to oiesis. One abnor a ity o the egakaryo oiesis in bone

ore ature ye oi ce ines, or exa e, granu ocytes, arrow tissue, however, is ronounce eo or his o the

erythrocytes, egakaryocytes, or ast ce s. egakaryocytic ce ine consisting o giant or s, icro-

Acquire ate et ys unction is co on y seen in the egakaryocytes, an nake ( yknotic) nuc ei. Another

ye o ro i erative syn ro es (see Cha ter 23): E , PV, an aturationa abnor a ity is the issociation o nuc ear-cyto-

i io athic brosis. P ate et aggregation atterns are o en not as ic aturation, inc u ing the a ount o ense granu es,

characteristic an cou re resent any co bination o ate- an the eve o ent o the e arcation e brane syste

et aggregation e ects. as we as the occurrence o e eri o esis (i.e., interna iza-

tion o he ato oietic ce s) a rea y in i ature or ega-
Polycythemia Vera karyob astic e e ents.

Patients with PV requent y e onstrate a co ex o A striking variety in the a earance o ense granu es o

he orheo ogica isor ers (high b oo viscosity at i er- the a ha ty e a so requent y exists. T ro bocytes show

ent rates o eviation, intensi e RBC aggregation, an giant or s with either hy ertro hy o the o en cana icu ar

ecrease e or abi ity o these ce s) an he ocoagu ation syste or an abun ance o ense granu es an beta g yco-

isor ers. gen accu u ation. Other re arkab e eatures inc u e a oca

Co ications o PV inc u e thro bosis an ara oxi- s onge- ike ro i eration o the o en cana icu ar syste

ca he orrhage. T e thro bosis see s to be re ate to the in any o the arge ate ets an giant an use granu es

height o the re ce vo u e with a subsequent increase in o the a ha an os io hi ic ty e. T ese abnor a ities in

b oo viscosity. Who e b oo viscosity ursues a rather inear egakaryocytes an thro bocytes ay have certain unc-

rate o rise, an ost hysicians re er to kee the atient’s tiona i ications (e.g., he orrhage an thro bosis) that

he atocrit be ow 45%. Increase who e b oo viscosity con- are o en encountere out o ro ortion to the ate et counts

tributes to vascu ar occ usions an reversib e esions, inc u - in this isor er.

ing cerebra an yocar ia in arction, as we as shortness o In a ition, those ano a ies in icate a isorganization

breath an hot f ushes, robab y cause by circu atory istur- o egakaryo oiesis, which ay contribute to the abnor-

bance. Patients with a b oo viscosity higher than twice the a re ease o actors ( ate et- erive growth actor an

nor a ean va ue ay be in anger o vascu ar occ usion. PF4) re o inant y invo ve in the rocess o ye o bro-

A corre ation has been revea e a ong the ara eters o sis. It has been ostu ate that ate et- erive growth ac-

RBC rheo ogica ro erties, he ostasis, an isease severity. tor an PF4 are invo ve in the i ba ance o the echanis

In so e cases, isor ers in the rheo ogica heno ena o o e u ary stro a aintenance, which triggers the bone
RBCs are a triggering echanis in the eve o ent o the arrow ye o brotic rocess. A re ationshi exists between

DIC syn ro e. the resence o ye o brosis an abnor a eve s o beta-

In the chronic hase o PV, atients with thro bohe or- thro bog obu in, PF4, an itogenic activity o ate et

rhagic co ications have higher ate et counts, ore severe ro uction.

ate et aggregation e ects, an increase as a eve s o

beta-thro bog obu in an brino e ti e A co are with Essential or Primary T rombocythemia (E )

atients who o not have co ications. However, thro bo- Essentia or ri ary thro bocythe ia (see Cha ter 23 or a

he orrhagic co ications are not re ictab e by changes u iscussion o E ) is characterize by a signi cant increase

in these ara eters in in ivi ua atients uring the chronic in circu ating ate ets, usua y in excess o 1,000 × 10 /L.
9
isease hase. P ate et or ho ogy revea s a nor a iscoi -sha e

T e as a eve o tissue as inogen activator anti- ce ; b ee ing ti e is nor a . In a ition, seu ohy erka e-

gen (t-PA-Ag) is signi cant y ecrease in atients with PV ia ay resu t uring the re aration o seru . Potassiu

co are with hea thy in ivi ua s. In contrast, atients with ro ate ets is not re ease uring the aggregation hase

s urious o ycythe ia an secon ary o ycythe ia exhibit but uring the egranu ation hase o the coagu ation

signi cant y increase concentrations o t-PA-Ag. T ere is rocess.

no signi cant i erence in t-PA-Ag eve s in o ycythe ic In atients with thro bocythe ia, the ean extent o

atients with or without thro boe bo ic isease. aggregation in uce by e ine hrine, co agen, or ADP is sig-

ni cant y ower than in nor a contro s. In ore than ha
Primary Myelof brosis o atients with thro bocythe ia, the ate et-rich as a

In a ition, the evo ution o e u ary brosis is thought to oes not res on to e ine hrine. T e tota ca ciu content

be associate with the striking re o inance o arge, aty i- o ate ets is a so signi cant y ower.

ca , ossib y overage , an hy er o y oi egakaryocytes

but not with an increase in recursor ce s. Miscellaneous Acquired Disorders Associated with

Dys egakaryocyto oiesis ea ing to an over ro uction Platelet Dysfunction

o e ective ate ets is the ost constant eature o ye o - Acquire e ects are seen in autoi une isor ers, such

brosis. Research n ings i y that the signi cant increase as SLE, rheu atoi arthritis (RA), I P, an sc ero er a.

in circu ating rogenitor ce s o the egakaryocyte ineage Fibrinogen egra ation ro ucts or brinogen s it ro ucts