The best replacement for spleen is pancreas.

The best alternatives to spleen are rated as following:
★★★★★  pancreas
★★★★  liver
★★★  kidney
★★  lymph node
★★  gallbladder
★  thymus
★  rib pain
  normal spleen
  rib injury
  lymph nodes
  liver enlargement

Your alternative for spleen is not listed? Suggest!
Speaking about spleen, one probably shouldn't forget about mono.

Other search terms related to spleen and their ratings are:
★★★★★ mono
★★★★ low platelet count
★★★ normal blood count
★ mononucleosis
★ lymphoma
★ anemia
granulomas
You have in mind a companion for spleen and it is not yet here? Propose!



Google Trends

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spleen
pancreas
liver