- Unicentric Castlemans: unknown etiology.
- Multicentric Castlemans: Systemic illness from dysregulation of cytokines; > 50% idiopathic
- Multicentric Castlemans: 40-50% related to HHV8 infxn in immuncompromised patients (e.g HIV); often hx other autoimmune dz.
- Unicentric: : usually focal adenopathy; sometimes sx related to compression of adjacent structures; sometimes mild systemic sx.
- Multicentric: F, C, sweats, adenopathy; can be recurrent; Can be very ill
- Unicentric: single focus of LN enlargement
- Multicentric: F, generalized ill appearance, diffuse adenopathy, organomegaly.