Coccyx Pain Diagnostic Workup: Necessity of MRI

American Journal of Physical Medicine and Rehabilitation

2010 April; 89 (4): S33.

Patrick M. Foye, M.D.

Tailbone Pain Center, UMDNJ-New Jersey Medical School, Physical Medicine and Rehabilitation, 90 Bergen Street, DOC-3100, Newark, NJ, United States, 07103. Phone: (973)972-2802. Fax: (973)972-2825.


Case presentation: A 54 year old male presented to a University-based, outpatient, musculoskeletal/pain physical medicine and rehabilitation practice. His chief complaint was several months of coccyx pain (tailbone pain), which began without any trauma. His pain was progressively worsening despite treatment by his primary physician, chiropractic treatments and use of nonsteroidals. He was otherwise healthy, without significant past medical history. Colonoscopy shortly after symptom onset was essentially unremarkable. Physical exam revealed no tenderness in the lumbar region, sacrum, sacroiliac joints, piriformis muscles, ischial bursae, or greater trochanters. However, there was exquisite focal tenderness along the distal coccyx. Sacral radiographs were essentially unremarkable.

Initial imaging studies with x-rays (radiographs): Coccygeal x-rays revealed that the distal coccygeal segment angled backwards (posteriorly) rather than the normal anterior angulation, thus seeming to correspond to his presenting symptoms and his site of tenderness to palpation.

Initial treatment: A fluoroscopically-guided focal steroid injection was provided there in an attempt to provide symptomatic relief, while insurance authorization was sought for a sacrum/coccyx MRI. The local anesthetic aspect of the injection provided 78% relief, per visual analog scale (pre-injection versus immediately post-injection).

Eventual MRI diagnosis: For two months, he declined the recommendations to undergo the MRI, but eventually did so due to worsening coccyx pain. The sacrum/coccyx MRI revealed a mass causing bony destruction of the left inferior sacrum at approximately S2 through S4, measuring 4.0 x 3.7 x 3.4 cm. Follow-up MRI with and without contrast confirmed the malignant, destructive nature of the mass, which extended into the soft tissue both anterior and posterior to the sacrum. The coccyx appeared uninvolved. Physical exam still revealed only coccyx, not sacral, tenderness.

Surgical treatment: He was sent for surgical and oncology consults, confirming an aggressive local malignancy (a primary bone cancer) needing surgical resection.

Conclusions: This case illustrates the importance of MRI in detecting cancers in patients with coccyx pain, especially in patients with worsening pain, non-traumatic onset, and/or failure to respond to initial treatments.

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