▁vessels . ▁ ▁T issue ▁for ▁diagn osis ▁can ▁be ▁obtained ▁via ▁fine - need le ▁asp iration , ▁skin ▁bi ops y , ▁or ▁ex cis ional ▁bi ops y . ▁ ▁Under ▁the ▁mic ros cope , ▁I H s ▁are ▁un enc aps ulated ▁aggreg ates ▁of ▁closely ▁pack ed , ▁thin - w alled ▁cap ill aries , ▁usually ▁with ▁end oth el ial ▁l ining . ▁Blood - filled ▁vessels ▁are ▁separated ▁by ▁sc ant ▁connect ive ▁t issue . ▁Their ▁lum ina ▁may ▁be ▁th rom b osed ▁and ▁organized . ▁Hem os ider in ▁p ig ment ▁de position ▁due ▁to ▁vessel ▁ru pt ure ▁may ▁be ▁observed . ▁ ▁The ▁GL UT - 1 ▁hist och em ical ▁marker ▁can ▁be ▁helpful ▁in ▁distingu ishing ▁I H s ▁from ▁other ▁items ▁on ▁the ▁differential ▁diagn osis , ▁such ▁as ▁v asc ular ▁mal form ations . ▁ ▁Tre at ment ▁ ▁Most ▁I H s ▁disappear ▁without ▁treatment , ▁leaving ▁minimal ▁to ▁no ▁visible ▁marks . ▁This ▁may ▁take ▁many ▁years , ▁however , ▁and ▁a ▁proportion ▁of ▁les ions ▁may ▁require ▁some ▁form ▁of ▁ther apy . ▁Ind ic ations ▁for ▁treatment ▁include ▁functional ▁imp air ment ▁( i . e . ▁visual ▁or ▁feed ing ▁comprom ise ), ▁ble eding , ▁potentially ▁life - th re aten ing ▁comp lications ▁( air way , ▁card iac , ▁or ▁he p atic ▁disease ), ▁and ▁risk ▁of ▁long - term ▁or ▁permanent ▁dis figure