Page 482 - Clinical Hematology_ Theory _ Procedures ( PDFDrive )

466 PART 6 ■ Neoplastic Disorders

signif c ntly shorter surviv l ti e th n those with he o-

globin concentr tion gre ter th n or equ l to 10 g/ L. A BOX 23-4

pl telet count less th n 100 × 10 /L lso i plies signif c ntly
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shorter surviv l ti e n is o prognostic signif c nce within

the f rst 6 onths o i gnosis. P tients with osteo yeloscle- Criteria for Diagnosis of Essential

rosis, s e onstr te on r iogr ph o the skeleton, h ve Thrombocytosis/ Essential

signif c ntly better prognosis co p re to those without Thrombocythemia *

osteo yelosclerosis. T e presence o osteo yelosclerosis 1. Persistent elev tion o pl telets (less th n 450 × 10 L)
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e erges s vor ble p r eter t 3 n 5 ye rs. Using in peripher l bloo

these three p r eters n spleen size, prognostic scoring 2. Signif c nt incre se (hyperpl si ) o eg k ryocytes in

syste h s been esigne ; it c tegorizes p tients into three the bone rrow

prognostic groups with highly i erent surviv l ti es (low- 3. Not eeting criteri o other MPNs

risk group, 69 onths; inter e i te-risk group, 33 onths; 4. De onstr tion o JAK2V617F or rel te ut tion, or

high-risk group, 4 onths). in the bsence o JAK2V617F, no evi ence or re ctive

In ition, jor thro boe bolic co plic tions th t thro bocytosis, or ex ple, in tion

contribute to shortene surviv l ti es re seen in pproxi-

tely one f h o p tients. *Di gnosis requires eeting ll three jor n two inor criteri .

Gener lly, chronic ph se o MF is ch r cterize by either

peripher l bloo or bone rrow bl st count less th n

10% co p re to the cceler te ph se o 10% to 19% n s re ctive pheno enon, secon ry to v riety o syste ic

the bl st ph se with ≥20%. P tients in the bl st ph se h ve con itions, or they y represent essenti l thro bocythe-

poor prognosis esti te t 3 to 5 onths. re t ent i , pri ry isor er o the bone rrow.

with in uction regi ens oes not i prove outco es,

unless it is ollowe i e i tely by he topoietic ste cell Diagnostic Characteristics

tr nspl nt tion.

T e i gnosis o essenti l thro bocythe i is i cult n

Treatment relies on the exclusion o other yeloproli er tive st tes n

nonhe tologic l illnesses ssoci te with n incre se
Asy pto tic p tients require no tre t ent. re t ent o concentr tion o pl telets. M jor criteri n ncill ry f n -

yelof brosis c n consist o perio ic tr ns usions o p cke ings ni este in essenti l thro bocythe i re presente

re bloo cells, n rogens, cytotoxic gents, n pl telet in Box 23.4.

re uction by pl teletpheresis. A inistr tion o prophyl c-

tic ntibiotics y lso be consi ere . Reco bin nt inter- Epidemiology

eron lph y be e c cious when use in the cellul r (i.e.,

proli er tive) ph se but less so when the rrow is f brotic Essenti l or pri ry thro bocythe i (essenti l thro -

or osteosclerotic. Mo er te oses o r i tion ther py to bocytosis) is the le st co on MPN. Essenti l thro bo-

the spleen h ve been e ective in controlling sy pto s. cythe i occurs ost requently ong persons in the

However, clinic l i prove ent er irr i tion is slow, f h n sixth ec es o li e. Men n wo en re equ lly

gr u l process. ecte .

Splenecto y y be ppropri te in so e circu st nces

(e.g., ssively enl rge spleen). Splenecto y in p tients Pathophysiology

with yelof brosis is ssoci te with n oper tive ort l-

ity r te o 13.4%, n e rly orbi ity r te o 45.3%, n Essenti l thro bocythe i is clon l isor er o ulti-

l te orbi ity r te o 16.3%. Al ost ll p tients with port l potenti l cell origin n belongs to the MPNs th t inclu e

hypertension n p in ul spleno eg ly, but only bout h l PRV, CML, n PMF. T is r re isor er inclu es uco-

o those with thro bopeni n ne i , h ve experience cut neous he orrh gic i thesis n thro boe bolic

relie o sy pto s or signs er splenecto y. T ere is no events. Both thro bocytosis n pl telet ys unction c n be

evi ence th t splenecto y ects surviv l in yelof brosis. responsible or the thro bohe orrh gic pheno en exhib-

Splenecto y in p tients with v nce yelof brosis is ite by p tients with this ise se. However, qu lit tive pl te-

p lli tive proce ure th t c rries subst nti l risk. let bnor lities r ther th n thro bocytosis re believe to
be the in c use o thro boe bolic events.

ESSENTIAL THROMBOCYTOSIS/ Karyotype

ESSENTIAL THROMBOCYTHEMIA

At le st three ourths o p tients h ve nor l k ryo-

Essenti l or pri ry thrombocythemia is ch r cterize by type. T e b l nce o p tients e onstr tes v ri ble chro-

signif c nt incre se in circul ting pl telets, usu lly in excess oso l bnor lities, with neuploi y being the ost

o 1,000 × 10 /L. Elev te pl telet counts y be encountere co on.
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