Retrorectal Epidermal Inclusion Cyst A Rare Cause Of Coccydynia

World Journal of Colorectal Surgery
Volume 4, Issue 4
2014
Article 2
Retrorectal Epidermal Inclusion Cyst A Rare
Cause Of Coccydynia Diagnosed By
Transperineal Ultrasonography
Mithilesh K. Pandey∗
Debajit R. Barman†
Kaushik Roy‡
Parimal Tripathy∗∗
∗
Nil
Ratan
Sirkar
Medical
College
and
Hospital,
[email protected]
†
Nil Ratan Sirkar Medical College and Hospital, Kolkata, India
‡
Nil Ratan Sirkar Medical College and Hospital, Kolkata, India
∗∗
Nil Ratan Sirkar Medical College and Hospital, Kolkata, India
c
Copyright 2015
The Berkeley Electronic Press. All rights reserved.
Kolkata,
India,
Retrorectal Epidermal Inclusion Cyst A Rare
Cause Of Coccydynia Diagnosed By
Transperineal Ultrasonography
Mithilesh K. Pandey, Debajit R. Barman, Kaushik Roy, and Parimal Tripathy
Abstract
Chronic coccydynia, local pain at coccygeal area, is a difficult problem diagnostically and
therapeutically. The term was coined by Simpson in 1861. It mostly labelled as idiopathic or
post-traumatic in origin. Various unusual pathological conditions have been described as a cause
of coccygodynia. We report a case of retrorectal cyst diagnosed with transcutaneous perineal ultrasonography in a 50 years-old female presenting as chronic coccydynia. Excision of the cyst
relieved her all symptoms. Histopathology concluded the lesion to be an epidermal inclusion cyst
. This report suggests that transperineal ultrasound can be considered an inexpensive alternative to more expensive imaging techniques when constrained by financial concerns. Precoccygeal
retrorectal epidermal inclusion cyst should be considered as arare differential diagnosis of coccygodynia, besides others retrorectal cysts.
KEYWORDS: : Coccygodynia, coccydynia, retrorectal cyst, precoccygeal epidermal inclusion
cyst, Transcutaneous perineal ultrasonography, coccygectomy
Pandey et al.: Retrorectal Epidermal Inclusion Cyst A Rare Cause Of Coccydynia D
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INTRODUCTION
Pain in the vicinity of the coccyx has numerous aetiologies like trauma, local infection, and tumours.
However, majority of coccygeal pain is idiopathic in nature. Precoccygeal epidermal inclusion cyst
presenting as a coccydynia was first reported by Jaiswal et.al in 2008 [1]. Presacral cysts are divided in
two major groups, teratomas and developmental cysts [2]. These presacral developmental cysts are rare
congenital lesions and the most common retrorectal cystic lesions identified in adults, occurring mostly
in middle-aged women [2, 3]. According to their origin and histopathologic features these are classified
as epidermoid cysts, dermoid cysts, enteric cysts (tailgut cysts and cystic rectal duplication), and
neuroenteric cysts [3]. Plain and contrast pelvic computed tomography (CT) or magnetic resonance
imaging (MRI) can locate the cyst adequately. Although less commonly utilized, transperineal
ultrasonography (USG) can be helpful in establishing diagnosis as is done in the present case.
CASE REPORT
We present the case of a 50 year-old female who was suffering from refractory coccydynia for 3 years.
She was not getting relief with conservative treatments. She was referred to department of
neurosurgery to rule out any neurological cause for her chronic suffering. The pain was localised at
coccygeal region, without any radiation, and mild in intensity. The pain increased with sitting/ squatting
posture especially during defecation. There was also history of recurrent episodes of acute severe pain
along with feeling of sense of heaviness and discomfort at natal cleft. There was no history of injury to
the local area. Clinically there was no neurologic deficits.
A vague induration was detected in the coccygeal region. Digital rectal examination the coccyx was
tender, and no intra/ extraluminal mass palpable. Patient was advised to undergo MRI of the pelvis but
could not because of financial constraints. Transcutaneous perineal USG was performed. USG
demonstrated a hypoechoic mass of 2.2cm x 1.5 cm in the retrorectal precoccygeal region with
extension in the subcutaneous plane Figure 1 [A,B,C]. On that basis, the cyst excision was planned
through posterior approach in prone position. A longitudinal posterior midline incision was performed
and a cystic lesion was dissected from precoccygeal retrorectal space Figure 2 [A, B]. The coccyx was
healthy and the cyst was adhered to it. Cyst was excised without any difficulty and coccyx was not
removed. The histopathologic examination confirms it as epidermal inclusion cyst Figure [3]. The patient
has been followed for 2 years and remains asymptomatic.
DISCUSSION
Intractable coccydynia can be a very debilitating disorder. It is generally labelled as idiopathic or posttraumatic in origin. Initially thought to be neurotic disorder, other suggested aetiologies of idiopathic
coccydynia are spasm of the muscles of the pelvic floor, anomalies of the soft tissues in the mid-sacral
region, chronic inflammation of an adventitious coccygeal bursa, and arachnoiditis of the lower sacral
nerve roots. Morphological abnormality of the coccyx, including increased intercoccygeal angle, spicule,
retroversion, and scoliosis, may be possible causes of idiopathic coccydynia [1].
The presacral space, which contains different types of embryonic tissue, is a potential site for several
tumour types including epidermoid cyst [2]. Most of the cystic neoplasms arising in the retrorectal
presacral space are congenital [4]. Epidermal inclusion cyst refers to those cysts that result from the
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Vol. 4, Iss. 4 [2014], Art. 2
implantation of epidermal elements in the dermis [3]. An epidermoid cyst is a common occurrence in
the skin. Such a cyst occurring in the retrorectal space, however, is extremely rare [5]. Our case appears
to be of the congenital variety, as there is no history of any antecedent trauma or local injections.
They become inflamed or secondarily infected which is partly due to chemotactic induction of
polymorphs by horny layer in the cyst [6]. Infective complications may occur and the increasing volume
of the cyst can cause clinical symptoms [4]. As in this case, intermittent acute exacerbation of coccygeal
pain occurred due to increasing volume of the cyst causing pressure on the coccyx.
More chronic cysts may exhibit calcification or a foreign body reaction. More rarely, malignancies,
including basal cell carcinoma, Bowen’s disease, squamous cell carcinoma, and even mycosis fungoides,
have developed in epidermal cysts with a possible role of repetitive trauma and inflammation [1, 3, 6].
They have a slowly-progressive growth that only lately can cause clinically remarkable symptoms. Most
patients are middle-aged women, as in our case. They are often asymptomatic and discovered
incidentally during evaluations such as USG, CT, MRI, and gynaecologic examination [4].
Transrectal ultrasonography (TRUS) appears to have utility in establishing the diagnosis of a retrorectal
tumour. Tomographic imaging, with either CT or magnetic resonance imaging (MRI), has become the
standard for the preoperative evaluation of retrorectal tumours. MRI with an endorectal coil can
provide detailed images depicting the relationship of the tumor with sacral nerve roots, the coccyx, and
the musculature of the pelvic floor [7]. Jaiswal et al was suggested, that patients with intractable
coccydynia should have a magnetic resonance imaging to rule out treatable causes of coccydynia [1].
In our case, MRI was advised but not performed due to patient financial constraints. As there was an
induration in the skin of coccygeal region there was a suspicion of perirectal abscess. Therefore we
proceeded with the less expensive transperineal USG which revealed a well defined cystic lesion in
retrorectal precoccygeal location.
Transperineal USG is well tolerated and uses generally available transducers that most radiography
practices already possess. Similar to TRUS, transperineal USG is low cost, high resolution, multiplanar,
and real time. Benefits include visualisation of perirectal processes several centimetres from the rectal
lumen. Transperineal USG is preferentially performed with a 5 to 10 MHZ linear array, curved linear
array, or sector transducer operating at the highest frequency that penetrates the desired anatomy [8].
Differential diagnoses that need to be considered are anal fistula, perirectal abscess, pilonidal disease,
other types of retrorectal congenital tumours, neurogenic tumours and osseous tumours [9]. A
multidisciplinary team with extensive knowledge of pelvic anatomy and expertise in pelvic surgery
including colorectal surgeons, neurosurgeons, and radiation oncologists is likely to improve the rate of
successful treatment [7].
There is almost no role for biopsy of a resectable retrorectal tumour prior to surgical resection and it is
considered by many to be contraindicated [2, 7]. There may be a limited role for biopsy in select lesions
suspicious for malignancy that may benefit from neoadjuvant radiotherapy to improve resectability or
local recurrence. In appropriate surgical candidates, all retrorectal tumours should be resected, even if
asymptomatic [7]. Surgical excision should be performed not only for relief of symptoms and diagnosis
but also to rule out uncommon and occasional malignancy [3].
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Three described approaches to resection are abdominal, perineal (transsacral), and combined or
abdominoposterior, each with its specific indications such as tumour size, location, presence of
malignancy, and bony invasion. The perineal-only approach is typically reserved for smaller retrorectal
tumours that lie mostly caudal to the S4 level. An abdominal-only approach may be utilized for high
retrorectal tumours that do not involve the sacrum and lie above S4. However, most large lesions are
best treated with a combined abdominoperineal approach [2, 7]. Posterior approach is indicated for low
or mid presacral space tumours. It is the most commonly utilized approach as done in our case [4].
Whether coccygectomy decreases recurrence rates is unclear. Various authors offer differing opinions
[10]. When the cyst is adhered to the coccyx or becomes malignant and invades the coccyx the residual
cells can cause recurrence [9]. Neoplastic cells are reported to develop easily in the coccyx; hence, a
coccygectomy is essential to cure the disease in such cases [9]. As in our case coccyx was healthy with
minimal adhesion to cyst wall so a coccygectomy was not performed and the patient was completely
relieved from her symptoms. Retrorectal precoccygeal epidermal inclusion cyst should be considered in
differential diagnosis of secondary coccydynia. Though the MRI, CT, and TRUS are the preferable
radiologic investigations perineal USG can be helpful in establishing the diagnosis. Transperineal USG
should be considered as a less expensive alternative in developing countries and for patients without
the economic means to undergo the preferred radiologic investigations. The selection of appropriate
patients before surgery for coccygectomy is extremely important.
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Zambrano- Medina L . Giant epidermoid presacral and retrorectal cyst: case report. Cir. 2009; 77(1):6972.
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6. Takematsu H, Terui T, Toinuki W, Tagami H. Leukocyte chemotactic properties of soluble horny
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about Retrorectal Developmental Cysts in Adults. J Korean Soc Colproctol 2011; 27(6):303-314.
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USG of the perineum was showed a hypoechoic mass in the retrorectal precoccygeal region.
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USG of the perineum was showed a hypoechoic mass in the retrorectal precoccygeal region.
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World Journal of Colorectal Surgery
USG of the perineum was showed a hypoechoic mass in the retrorectal precoccygeal region.
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Pandey et al.: Retrorectal Epidermal Inclusion Cyst A Rare Cause Of Coccydynia D
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Operative photograph of the posterior midline incision with exposure of the coccyx.
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World Journal of Colorectal Surgery
Operative photograph cyst dissection from the coccyx.
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Histopathology: The cyst wall was lined by stratified squamous epithelium and filled with keratinous material.
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