- Cystic - see also condition
- Cysticerciasis 123.1
- Cysticercosis (mammary) (subretinal) 123.1
- Cysticercus 123.1
- Cystinosis (malignant) 270.0
- Cystinuria 270.0
- Cystitis (bacillary) (colli) (diffuse) (exudative) (hemorrhagic) (purulent) (recurrent) (septic) (suppurative) (ulcerative) 595.9
- Cystocele (-rectocele)
- Cystoid
- Cystolithiasis 594.1
- Cystoma (M8440/0) - see also Neoplasm, by site, benign
- Cystoplegia 596.53
- Cystoptosis 596.8
- Cystopyelitis (see also Pyelitis) 590.80
- Cystorrhagia 596.8
- Cystosarcoma phyllodes (M9020/1) 238.3
- Cystostomy status V44.50
- Cystourethritis (see also Urethritis) 597.89
- Cystourethrocele (see also Cystocele)
- Cytomegalic inclusion disease 078.5
- Cytomycosis, reticuloendothelial (see also Histoplasmosis, American) 115.00
- Cytopenia 289.9
