▁are ▁usually ▁d ys pl astic . ▁ ▁Di agn osis ▁Ep ide mi olog ically , ▁the ▁dis order ▁usually ▁develop s ▁slowly ▁and ▁is ▁mainly ▁observed ▁in ▁people ▁over ▁the ▁age ▁of ▁ 5 0 . ▁It ▁may ▁also ▁develop ▁as ▁a ▁side - effect ▁of ▁treatment ▁with ▁some ▁dru gs ▁that ▁target ▁h emat ological ▁dis orders , ▁such ▁as ▁poly cy th emia ▁ver a ▁or ▁chron ic ▁my el oid ▁le uk emia . ▁Di agn osis ▁of ▁my el of ib ros is ▁is ▁made ▁on ▁the ▁basis ▁of ▁b one ▁mar row ▁bi ops y . ▁A ▁physical ▁exam ▁of ▁the ▁ab d omen ▁may ▁reve al ▁en larg ement ▁of ▁the ▁s ple en , ▁the ▁li ver , ▁or ▁both . ▁ ▁Blood ▁tests ▁are ▁also ▁used ▁in ▁diagn osis . ▁Primary ▁my el of ib ros is ▁can ▁begin ▁with ▁a ▁blood ▁picture ▁similar ▁to ▁that ▁found ▁in ▁poly cy th emia ▁ver a ▁or ▁chron ic ▁my el oid ▁le uk emia . ▁Most ▁people ▁with ▁my el of ib ros is ▁have ▁moder ate ▁to ▁severe ▁an emia . ▁Event ually ▁th rom b oc yt open ia , ▁a ▁decrease ▁of ▁blood ▁plate lets ▁develop s . ▁When ▁viewed ▁through ▁a ▁mic ros cope , ▁a ▁blood ▁sm ear ▁will ▁appear ▁marked ly ▁ab normal , ▁with ▁presentation ▁of ▁p ancy t open ia , ▁which ▁is ▁a ▁reduction ▁in ▁the ▁number ▁of ▁all ▁blood ▁cell ▁types : ▁red ▁blood