A Case of Coccygeal Pad with a History of Coccygeal Protrusion since Birth: Review of the Literature and Reconsideration of Pathogenesis

Abstract

Coccygeal pad is a densely collagenous lesion arising in the sacrococcygeal area with unclarified etiology. We report a case of a 20-year-old man with a 60×30 mm, pink nodule in his coccygeal region. He had noticed the lesion 5 years previously, although the skin-colored protrusion in the coccygeal region had been observed by his mother since birth. Imaging studies including X-ray radiography and CT scans of the pelvis revealed that the coccyx was sharply angulated forward between the first and second segments, almost perpendicular to the axis. Furthermore, the lower half of the sacrum showed a straight line without the posteriorly convex curvature seen in a normal spine.

We reviewed the literature and disclosed that more than 40% of such patients that were reported with evaluable imaging studies exhibited a loss of the normal convex curvature in the lower part of the sacrum. Abnormal spinal curvature of the lower sacrum could be one of the congenital etiological factors of the development of coccygeal pad and also of anterior angulation of the coccyx, by strengthening mechanical stimulation.