Retroperitoneal congenital epidermoid cyst misdiagnosed as a solid pseudopapillary tumor of the pancreas:A case report

INTRODUCTION

Epidermoid cysts are tumor-like benign lesions that can be divided into congenital and acquired lesions.Congenital tumors often occur in the central nervous system and reproductive system and originate from the ectoderm of the skin at an early stage of the embryo.Acquired tumors are mostly caused by trauma and surgery wherein the epidermis is introduced into deep tissue.Epidermoid cysts are commonly found in the brain,trunk and neck and less commonly reported in the testis,penis,spleen and kidney[1,2].

The incidence of retroperitoneal epidermoid cysts is less than 1/40000,and most of them grow in the presacral region[3].Retroperitoneal epidermoid cysts are less common at the back of the pancreatic neck or the root of mesenteric vessels.Because of the atypical location in this case,the cyst was misdiagnosed as a solid pseudopapillary tumor of the pancreas(SPTP)before laparotomy.

CASE PRESENTATION

Chief complaints

A 25-year-old Chinese woman experienced a one-month history of upper abdominal pain,abdominal distension and vomiting.

Every morning I used to go the place where the incident happened. It was Monday morning again and the weather was bad. It was extremely6 bad! When I started to step my foot the rain started to fall. I stepped backward7 for I didn’t want to get wet. The man far behind me was wet. I got cold. I got my umbrella in my bag and started walking to the man’s direction. I was surprised the man standing is the man that I’ve been looking for! He smiled and said, “It was a year I been waiting this moment and praying someday we are going to meet again and this is it...”

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History of present illness

There were several reasons for the mass to have been misdiagnosed as an SPTP.First,the patient was a young woman.Second,the mass was mainly located on the left side of the pancreatic head and behind the pancreatic neck,which led us to believe that the cyst may have originated from the pancreas.Third,preoperative images of retroperitoneal epidermoid cysts are similar to those of SPTPs.

The patient had no previous history of pancreatitis,trauma,surgery or a malignant tumor.

History of past illness

She rang the bell, and scarcely had she touched it before she found herself in a chamber2 where a bed stood ready made for her, which was as pretty as anyone could wish to sleep in

Personal and family history

The authors declare that they have no conflicts of interest.

Physical examination

The physical examination revealed a firm abdominal mass reaching the navel,and the rest of the examination revealed no abnormalities.

Laboratory examinations

Laboratory tests were normal.

Imaging examinations

Computed tomography(CT)detected a 98 mm × 63 mm × 54 mm subcircular mass in the uncinate process of the pancreas;the boundary was clear,and the adjacent tissue was pressed upon,with multiple spots and granular dense shadows observed.The dual-phase CT values were approximately 30 to 36 HU,and the density of the mass(which was considered to be an SPTP)was inhomogeneous(Figure 1A).

The incidence of retroperitoneal congenital cysts is approximately 1/40000-1/63000.The main types of these cysts are epidermoid cysts,dermoid cysts,cystic hamartomas,teratomas and malignant teratomas[5].

During the Great Depression,work was Hard to find, so Grandpa did whatever jobs he could. He dug ditches during the week and on weekend he and Grandma dug a garden to grow some of their own food.

FINAL DIAGNOSIS

Postoperative pathology showed an epidermoid cyst.

TREATMENT

The patient underwent a median incision of the upper abdomen under general anesthesia.When the transverse colon was lifted upward,we observed a large cystic mass of approximately 100 mm × 70 mm × 60 mm with an intact wall.The lesion was located behind the pancreas neck,with the superior mesenteric artery(SMA)and horizontal part of the duodenum under compression;the right margin adhered closely to the superior mesenteric vein(SMV),and the left margin was close to the inferior mesenteric vein(IMV),caudally extending to separate the SMV and SMA(Figure 2A).We performed complete resection of the tumor.The cyst was excised after mobilization of the SMV and splenic vein(SV),which were found on the right side and cephalic side,respectively,of the tumor.During surgery,special attention was given to the connection between the lesion and the pancreas.The incidence of recurrence for retroperitoneal cysts is higher than that of other forms of cysts,as their proximity to major blood vessels and vital structures can make retroperitoneal cysts difficult to completely excise.Grossly,the cyst was approximately 10 cm in the largest dimension(Figure 2B).

OUTCOME AND FOLLOW-UP

The patient recovered well and was discharged one week after the operation.Postoperative pathology showed an epidermoid cyst(Figure 3A).Two months later,enhanced CT revealed a normal shape of the SMV and SMA,no intravascular thrombus,no pseudoaneurysm,no obvious peripancreatic effusion,and no tumor recurrence or metastasis(Figure 3B).

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DISCUSSION

The case was diagnosed as a retroperitoneal congenital epidermoid cyst for several reasons.First,the tumor was located at the back of the neck of the pancreas and the root of the SMA;second,the patient had no history of trauma or surgery.

The wall of the epidermoid cyst was composed of stratified squamous cells.The keratin and cholesterol that filled the cyst were gray–white,caseous,keratinized substances mixed with shed,broken epidermal cells.Epidermoid cysts are slow-growing benign tumors composed of epithelial cells[4].

Magnetic resonance imaging(MRI)detected one 91 mm × 72 mm × 63 mm mass below the pancreas,which appeared hypointense on T1-weighted imaging and hyperintense on T2-weighted imaging,T2-weighted fat suppression imaging,and diffusion-weighted imaging(DWI;b1200).The wall of the mass showed progressive enhancement.The tumor was adjacent to the pancreas,and the uncinate process was suspected to be the initial site of the tumor(which was considered to be an SPTP)(Figure 1B).

Informed written consent was obtained from the patient for publication of this report and any accompanying images.

CT features of epidermoid cysts include discrete lesions,thin and smooth cystic walls and homogeneous liquid density shadows[6].On MRI,these cysts appear hypointense on T1-weighted imaging and hyperintense on T2-weighted imaging.However,some scattered low-density foci can be observed on T2-weighted imaging,which may be related to keratin in the cyst[6].Because there are no vessels in the cysts,the masses are not enhanced by contrast medium.Retroperitoneal epidermoid cysts are rare and lack imaging specificity;therefore,it is difficult to distinguish them from other cystic tumors.

The first report of SPTP was by Frantz in 1959.SPTPs are mostly benign or low-grade malignant tumors and often occur in women,mainly between the ages of 20 and 30 years[7,8].SPTPs are mostly circular or subcircular and can be located in any position on the pancreas[9].SPTPs can be divided into three types: Solid,cystic-solid and cystic.On CT,the cystic type appears as an area of low density and is not enhanced by contrast medium.On MRI,the cystic type is hypointense on T1-weighted imaging,hyperintense on T2-weighted imaging,somewhat hyperintense on DWI imaging,and marginally strengthened on enhanced imaging.

The patient developed epigastric pain without obvious cause one month prior,and she had symptoms of nausea and vomiting.She experienced no hematemesis or bloody stool,no chills or fever,and no significant weight loss.

Surgery is the main method of treatment for retroperitoneal epidermoid cysts.Because this disease is rare,it is easily confused with other types of tumors of the abdominal cavity.Misdiagnosis can lead to inappropriate surgery,increasing the risks of postoperative complications and mortality and thereby leading to significantly worse quality of life of patients.In the present case,careful exploration during the operation revealed that the tumor originated from the root of the SMA and failed to invade the pancreas;thus,fortunately,the woman avoided pancreaticoduodenectomy or middle pancreatectomy.In addition,with the continuous growth of lesions,inflammatory adhesion occurs around vital vessels and organs,which makes the lesions difficult to completely excise.

CONCLUSION

In summary,retroperitoneal epidermoid cysts around the pancreas are easily misdiagnosed as a cystic SPTP.Because of their different biological characteristics and surgical methods used for retroperitoneal epidermoid cysts and SPTP,surgeons should pay more attention to preoperative diagnosis to reduce severe surgical complications and improve the quality of life of patients.

FOOTNOTES

Ma J wrote and edited the original draft;Zhu L contributed to data collection and analysis;Zhou CP reviewed the literature,Zhang YM reviewed and approved the final manuscript;all authors have read and approve the final manuscript.

I believe honesty is one of the greatest gifts there is. I know they call it a lot of fancy names these days, like integrity and forthrightness1. But it doesn t make any difference what they call it; it s still what makes a man a good citizen. This is my code, and I try to live by.

In the years to follow, the answers began to arrive, clear and satisfying beyond my most optimistic anticipation21. One of the answers was Enchanted22 Hills, where my nurse friend and I have the privilege of seeing blind children come alive in God’s out-of-doors. Others are the never-ending sources of pleasure and comfort I have found in friendship, in great music, and, most important of all, in my growing belief that as I attune23 my life to divine revelation, I draw closer to God and, through Him, to immortality24.

Patients with retroperitoneal epidermoid cysts may have related symptoms,such as abdominal distension,abdominal pain,vomiting and constipation,depending on the location and volume of the tumor.Female patients are easily misdiagnosed with gynecological diseases.Some patients without clinical symptoms are diagnosed as a result of imaging examination.

The patient had her menarche at the age of 14,and her menstrual cycle was regular.Her parents had no related diseases.

The authors have read the CARE Checklist(2016),and the manuscript was prepared and revised according to the CARE Checklist(2016).

This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers.It is distributed in accordance with the Creative Commons Attribution NonCommercial(CC BYNC 4.0)license,which permits others to distribute,remix,adapt,build upon this work non-commercially,and license their derivative works on different terms,provided the original work is properly cited and the use is noncommercial.See: http://creativecommons.org/Licenses/by-nc/4.0/

This was my third year selling fireworks for the Chaparral High School Band Booster Club, and I took pride in my knowledge of these treats for the eyes and ears. Thanks to my son, I know what every one of these does or at least what it was designed to do.

China

Jun Ma 0000-0003-2547-8257;Ya-Ming Zhang 0000-0002-7020-7379;Chao-Ping Zhou 0000-0001-6610-2091;Lei Zhu 0000-0002-7855-2011.

Ma YJ

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She took her sons shopping. Clerks gasped14 when her sons made grunting15 sounds. And now, she knew about the other women. Sometimes her husband didn t bother to come home. Her friends quit calling her and Marianne felt a biting loneliness.

Ma YJ