epipygus

ep·i·py·gus

(ep'i-pī'gŭs),
Unequal conjoined twins in which the smaller, incomplete parasite is attached to the buttock of the larger autosite. See: pygomelus, conjoined twins.
[epi- + G. pygē, buttocks]
Farlex Partner Medical Dictionary © Farlex 2012

epipygus

(ep?i-pi'gus) [Gr. epi, upon, + pyge, buttocks]
A developmental anomaly in which an accessory limb is attached to the buttocks.
See: pygomelus
Medical Dictionary, © 2009 Farlex and Partners