An Unusual Cause of Pelvic Pain

Case Presentation


A 33 y/o F p/w 2 day hx rectal and pelvic pain.  Patient awoke with dull rectal pain that became acutely worse with exertion. Pain is constant, dull, pressure-like pain with intermittent episodes of sharp pain starting on the right side of the rectum and extending into the buttock/sacrum. Worse with bowel movements, twisting, abduction of legs and walking; improved with recumbence. Last bowel movement day PTA. No melena/hematochezia. No anal intercourse or trauma. No abdominal pain/nausea/vomiting. No anorexia. No dysuria/hematuria/vaginal discharge. No fevers/chills.  No history of similar pain in the past.  No history of ovarian pathology or ruptured or hemorrhagic cysts. Patient has tried NSAIDS for pain control with mild relief.

PMH/PSH:  hypothyroidism, multinodular goiter, s/p thyroidectomy
Meds: none
Allergies: penicillin (rash)
SHx: denies tobacco, etoh, or illicits


VS- 36.6°C temporal, HR 88, RR18, BP 106/75, sat 99%RA
Gen:  lying supine, appears uncomfortable
Abd:  soft, normal bowel sounds, no distention, no mass, +ttp suprapubic region bilaterally without guarding or rebound, no cva ttp
Rectal: brown stool guaiac negative, +ttp anterior rectal wall, no fissures or external hemorrhoids
GU: normal external genitalia, no lesions/vesicles, no vaginal discharge, cervical os closed, no cmt, no adnexal tenderness, +palpable fullness cul de sac

ED Actions Taken

CT scan of the abdomen/pelvis was performed with IV and PO contrast and later in the patient course an MRI of the lumbosacral spine was done.


What findings are present on CT and MRI images?



Bonus: What incidental finding is outlined in 3 CT images below?



CT scan and MRI images demonstrate large Tarlov cysts on the S1, S2 nerve roots bilaterally measuring up to 3.8 cm extending out of the neural foramina into the pelvis causing mild compression of the rectum without evidence of obstruction.


Bonus answer: CT images 5-7 outline a horseshoe kidney.

Background Information

  • Tarlov cysts are spinal extradural CSF-filled perineural cysts.
  • The pathogenesis of Tarlov cysts is unknown.
  • Inflammation within the subarachnoid space, traumatic hemorrhage, pseudomeningoceles, diverticula from persistent embryonic fissures or hydrostatic cerebrospinal fluid pressures are frequently cited theories.
  • Pain is caused when cyst distention activates neural, dural, or bone nociceptors or causes compression on adjacent structures.
  • Tarlov cysts are common findings on imaging with a reported incidence on MRI ranging from 1.5-4.6%.Symptomatic Tarlov cysts, however, are rare accounting for <1 % of the total.
  • Tarlov cysts occur most frequently at the sacral levels, but can occur anywhere along the spinal canal and are often multiple and bilateral.
  • Tarlov cysts can cause sacral pain, back pain, radicular pain, abdominal pain, urinary and fecal incontinence, dyspareunia, and paresthesias.
  • The diagnosis of a symptomatic Tarlov cyst is made when a large Tarlov cyst is in proximity to structures that are linked with a patient’s symptoms in the absence of other pathology.
  • Treatment is controversial and varies from medical management and pain relief to surgery.


  • It is important to pursue further workup and imaging when pathology is suspected even if a specific suspected diagnosis is elusive or uncertain.
  • Consider symptomatic Tarlov cysts as a cause of symptoms when they are present on imaging and a thorough workup does not demonstrate other pathology.

Case Resolution

The patient’s pain persisted, and a few months after presentation she underwent elective surgical resection of the Tarlov cysts with resolution of symptoms.


  • Cantore G et al. “Sacral Tarlov Cyst.” World Neurosurgery 2013; 79(2):381-389.
  • Hiers RM et al. “Hiding in Plain Sight: A Case of Tarlov Perineural Cysts.” The Journal of Pain 2010; 11(9):833-837.
  • Kim K, Chun SW, Chung SG. “A Case of Symptomatic Cervical Perineural (Tarlov) Cyst: Clinical Manifestation and Management.” 2012; 41:97-101.
  • Murphy KJ et al. “Tarlov Cysts: An Overlooked Clinical Problem.” Seminars in Musculoskeletal Radiology 2011; 15(2): 163-167.
  • Oaklander AL et al. “Case 7-2013: A 77-Year-Old Women with Long-Standing Unilateral Thoracic Pain and Incontinence.” N Eng J Med 2013; 368(9):853-861.
  • Park HJ et al. “Two Cases of Symptomatic Perineural cysts (Tarlov Cysts) in One Family – a Case Report.”Journal of the Korean Neurosurgical Society 2008; 44(3): 174-177.
  • Sen RK et al. “ Tarlov Cysts: A Report of two cases.” Journal of Orthopaedic Surgery 2012; 20(1):87-89.
  • Tarlov IM. “Perineural Cysts of the Spinal Nerve Roots.” Arch Neurol Psychiatry 1938; 40:1067-1074.
Edited by Adaira Landry

One thought on “An Unusual Cause of Pelvic Pain”

  1. Would consider the surgery but cost is too great. Doc said I’d need two to get at all the cysts and I can’t even afford one. Getting the word out that tarlov cysts do indeed cause pain is a step in the right direction for all of us.

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