A pelvic digit, pelvic finger, or pelvic rib is a rare congenital abnormality

Congenital abnormality

A congenital anomaly is a condition which is present at the time of birth which varies from the standard presentation....

 in humans, in which bone tissue

Osseous tissue

Osseous tissue, or bone tissue, is the major structural and supportive connective tissue of the body. Osseous tissue forms the rigid part of the bone organs that make up the skeletal system.-Formation:Bone tissue is a mineralized connective tissue...

 develops in the soft tissue

Soft tissue

In anatomy, the term soft tissue refers to tissues that connect, support, or surround other structures and organs of the body, not being bone. Soft tissue includes tendons, ligaments, fascia, skin, fibrous tissues, fat, and synovial membranes , and muscles, nerves and blood vessels .It is sometimes...

 near the pelvis, resembling a rib

Rib

In vertebrate anatomy, ribs are the long curved bones which form the rib cage. In most vertebrates, ribs surround the chest, enabling the lungs to expand and thus facilitate breathing by expanding the chest cavity. They serve to protect the lungs, heart, and other internal organs of the thorax...

 or finger

Finger

A finger is a limb of the human body and a type of digit, an organ of manipulation and sensation found in the hands of humans and other primates....

 and often divided into one or more segments with pseudo-articulations. Pelvic digits are typically benign and asymptom

Symptom

A symptom is a departure from normal function or feeling which is noticed by a patient, indicating the presence of disease or abnormality...

atic, and are usually discovered accidentally. Approximately 40 cases have been reported.

The pelvic digit was first reported by Sullivan and Cornwell in 1974. Pelvic digits may be located at any level of the pelvis, the lower ribs, or even the anterior abdominal wall. It is theorized that pelvic digit anomalies arise during the mesenchymal stage of bone growth, within the first six weeks of embryogenesis

Embryogenesis

Embryogenesis is the process by which the embryo is formed and develops, until it develops into a fetus.Embryogenesis starts with the fertilization of the ovum by sperm. The fertilized ovum is referred to as a zygote...

. Their formation may result from a failure of the primordium

Primordium

A primordium , in embryology, is defined as an organ or tissue in its earliest recognizable stage of development. Cells of the primordium are called primordial cells...

 of the coccyx

Coccyx

The coccyx , commonly referred to as the tailbone, is the final segment of the vertebral column. Comprising three to five separate or fused vertebrae below the sacrum, it is attached to the sacrum by a fibrocartilaginous joint, the sacrococcygeal symphysis, which permits limited movement between...

 to fuse to the vertebral column

Vertebral column

In human anatomy, the vertebral column is a column usually consisting of 24 articulating vertebrae, and 9 fused vertebrae in the sacrum and the coccyx. It is situated in the dorsal aspect of the torso, separated by intervertebral discs...

, leading to the independent development of a proto-rib structure.

External links

• Radiographs of a pelvic digit
• "Case report 32 " in Skeletal Radiology (full text requires subscription)
• "The pelvic digit: five new examples of an unusual anomaly" in Skeletal Radiology (full text requires subscription)
• "The Pelvic Digit – A Rare Developmental Anomaly" in Acta Radiologica (full text requires subscription)