Incidental finding of a true human tail in an adult: a case report

True human tails are rare vestigial structures that are typically removed in childhood. Here a case is presented in which an inconspicuous sacrococcygeal tail was incidentally discovered in late adulthood. A 56-year-old man with no significant past medical history presented to a dermatology clinic with a chief complaint of a hyperpigmented lesion on his central back. However, on full body skin exam, a separate flesh-colored 0.7 cm × 0.5 cm appendage was discovered in the midline sacrococcygeal region. This lesion had been present and unchanged since childhood. This particular lesion was removed via shave biopsy. Microscopic exam found it to be consistent with a diagnosis of a true human tail. There were no apparent involved spinal cord structures, and no further treatment was thought to be necessary. Human tails are congenital anomalies associated with occult spinal lesions in about 50% of cases. Therefore, it is in these patients' best interest to thoroughly evaluate for spinal cord involvement prior to biopsy. There is a relative lack of literature published on the topic, and a greater awareness of human tails would be helpful to ensure their inclusion in a differential diagnosis for persistent sacrococcygeal lesions in patients of any age.