Pelvic digit, also known as a pelvic rib, pelvic finger or 11th finger, is a rare congenital abnormality where there is development of bony tissue in the soft tissue pelvis and less commonly in the abdomen. They can be associated with one or more pseudo-articulation. They are usually unilateral.
Pathogenesis is unknown but is thought to occur during early embryogenesis from non-fusion of the vertebral column and the superior part of the coccyx and subsequent independent development of the intervening cartilaginous segment 4.
Treatment and prognosis
It is a benign entity and if incidentally discovered no further investigation is required.
General imaging differential considerations include:
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- 4. Pandey V, Thakur AS, Acharya KK, Rao PS. The pelvic digit "eleventh finger". Indian journal of orthopaedics. 43 (1): 97-8. doi:10.4103/0019-5413.45332 - Pubmed