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, Kolkata, India, [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

Copyright c 2015 The Berkeley Electronic Press. All rights reserved. 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 ul- trasonography 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 alterna- tive to more expensive imaging techniques when constrained by financial concerns. Precoccygeal retrorectal epidermal inclusion cyst should be considered as arare differential diagnosis of coccy- godynia, 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 1

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 post- traumatic 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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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.

REFERENCES

1. Jaiswal A, Shetty A P, Rajasekaran S; Precoccygeal epidermal inclusion cyst presenting as coccygodynia. Singapore Med J. 2008; 49(8):214. 2.Sierra-Montenegro E, Sierra-Luzuriaga G, Leone-Divanna G, Salazar-Menendez V, Quinonez-Auria C, Zambrano- Medina L . Giant epidermoid presacral and retrorectal cyst : case report. Cir. 2009; 77(1):69- 72. 3. Vishal Yadav, Raviraj Jadhav, Ali Reza Shojai, G. S. Narshetty. Post Anal Epidermoid Cyst - Obscure Cause For Low Backache. World Journal of Colorectal Surgery. Vol. 3, Iss. 1 [2013], Art. 15. 4. Negro F, Mercuri M, Ricciard V, Massari M, Destito C, Mafucci S, Coza T. Presacral epidermoid cyst . A case report . Ann Ital. Chir. 2006; 77(1):75-7. 5. Sasaki A, Sugita S ,.Horimi K, Yasuda K, Inmata M, Kitano S. Retrorectal epidermoid cyst in an elderly woman: report of a case . Surg. Today. 2008; 38(8):761-4. 6. Takematsu H, Terui T, Toinuki W, Tagami H. Leukocyte chemotactic properties of soluble horny contents in epidermal cysts. Arch Dermatol Res. 1987; 279(7):449–53. 7. Sean C. Glasgow, David W. Dietz. Retrorectal Tumors. Clin Colon Rectal Surg. 2006; 19(2): 61–68. 8. Rubens DJ , Strang JG, Bogineni misra S, Wexler LE. Transperineal sonography of the rectum: anatomy and pathology revealed by sonography compared with CT and MR imaging .AJR Am J Roentgenol. 1998; 170(3):637-42. 9. Sung Wook Baek, Haeng Ji Kang, Ji Yong Yoon, et al. Clinical Study and Review of Articles (Korean) about Retrorectal Developmental Cysts in Adults. J Korean Soc Colproctol 2011; 27(6):303-314. 10 . Ng E W, Porcu P, Loehrer P J. Sacrococcygeal teratoma in adults: case reports and a review of the literature. Cancer. 1999; 86:1198–1202.

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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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USG of the perineum was showed a hypoechoic mass in the retrorectal precoccygeal region.

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Operative photograph of the posterior midline incision with exposure of the coccyx.

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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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