British Journal of Radiology (2006) 79, e120-e122
© 2006 British Institute of Radiology
doi: 10.1259/bjr/33507627
Primary extragonadal retroperitoneal teratoma in an adult
K Taori, MD
J Rathod, MBBS
A Deshmukh, DMRD, DNB
V Singh Sheorain, MBBS
R Jawale, MBBS
R Sanyal, MBBS
M Bhagat, MBBS
and
S Jumle, MBBS
Department of Radiology, Government Medical College, Nagpur, 440003, India
Correspondence: Dr Kishor Taori, Department of Radiology, Government Medical College, Nagpur, 440003, India. E-mail: veeru_5{at}yahoo.com; kishortaori{at}yahoo.co.in.
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Abstract
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Primary retroperitoneal teratoma is a rare entity in adults. It has a distinctive imaging appearance. We describe a case of a 22-year-old patient who was referred to our hospital with the complaint of abdominal distension. Radiological work-up disclosed a retroperitoneal teratoma. Laparotomy with tumour resection was performed. Pathological examination revealed a benign cystic teratoma. The patient is doing well at follow-up.
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Introduction
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Teratomas are congenital tumours that contain derivatives of all three germ layers. They generally arise in the gonads, but several cases were found in extragonadal sites such as the sacrococcygeal region, mediastinum, neck and retroperitoneum [1].
Retroperitoneal teratomas often occur in infancy and childhood. In adults, retroperitoneal teratomas are rare. In this article, we describe an unusual case of a retroperitoneal teratoma in a 22-year-old patient with successful surgical treatment. Its clinical presentation, diagnosis and treatment are reviewed.
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Case report
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A 22-year-old male suffered from abdominal distension for 2 years. There was no abdominal pain, weight loss, bowel or urinary complaints. On examination, a large mass was palpable in the epigastric area extending to the central abdomen. The rest of the examination was unremarkable. Routine blood tests and urinalysis were all within normal limits. The serum levels of tumour markers alpha-fetoprotein (AFP) and carcinoembryonic antigen (CEA) were not raised.
A plain abdominal radiograph showed a well defined, predominantly lucent lesion with sheet-like calcification in the left upper and central abdomen with displacement of bowel loops (Figure 1
). Ultrasound demonstrated a large, complex, densely echogenic mass, suggestive of a fatty nature to the mass with sheet-like and curvilinear calcifications (Figure 2). Ultrasound of the testes did not show any evidence of primary or burned out testicular tumour.
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Figure 1. Plain abdominal radiograph shows large lucent lesion with sheet like calcification in the left upper and central abdomen with displacement of bowel loops.
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There was no ascites. Axial non-contrast enhanced CT of the abdomen (Figure 3a) in addition revealed multiple fat fluid levels. A rounded bunch of linear isodense elements possibly representing hair-plug was also seen. Splenic artery and vein were stretched and displaced anteriorly (Figure 3b). There was no lymphadenopathy.
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Figure 3. (a) Non-contrast enhanced axial CT of upper abdomen shows complex fat-density mass-lesion with fat-fluid levels (black arrow), rounded bunch of linear isodense elements possibly representing hair-plug (arrowhead), and curvilinear and sheet like calcifications (white arrow). (b) Contrast enhanced axial CT of abdomen shows anterior displacement of pancreas and splenic vessels (arrow).
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Exploratory laparotomy revealed a large cystic mass behind the descending colon and pancreas. It was located in the retroperitoneal compartment and extended from the left hemidiaphragm down to the iliac blades, and it was crossing the midline. The entire tumour was excised. Macroscopically, the encapsulated mass measured 20 cmx12 cm. Microscopically, it presented as a cystic tumour comprising squamous epithelium, skin adnexa, bone, marrow tissue, ciliated columnar epithelium, fat and nerve. It was compatible with the diagnosis of benign cystic teratoma. Post-operative course was uneventful.
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Discussion
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Overall retroperitoneal teratomas constitute less than 10% of all primary retroperitoneal tumours [2]. They are rare in adults. Less than 20% of these patients develop tumours over the age of 30 years. They usually occur more in children. Approximately half of the cases are found in the first decade of life. The incidence of retroperitoneal teratoma in females is twice that in males [3]. In Taiwan, three similar cases of adult onset retroperitoneal teratoma have been published previously [4–6].
Teratomas arise from germ cells that fail to mature normally in the gonadal locations. These totipotent cells can differentiate into tissue components representing derivatives of mesoderm, ectoderm and endoderm [2]. The distribution of teratomas are described in order of decreasing frequency: in the ovaries, the testes, the anterior mediastinum, the retroperitoneal space, the presacral and coccygeal areas, pineal and other intracranial sites, the neck and abdominal viscera other than the gonads [1]. The migratory property of germ cells would explain teratomas in these extragonadal sites, which generally occur along midline structures [2]. Retroperitoneal teratomas are often located near the upper pole of the kidney, with preponderance on the left side [1].
Retroperitoneal teratomas are usually asymptomatic. When compression of the surrounding structures occurs, patients may have abdominal distension and pain, nausea and vomiting [2]. Malignant teratomas tend to progress rapidly [3].
Malignant change in teratomas was higher in adults than in children, with incidences of 26% and 10%, respectively [1, 7]. Malignant teratomas may cause a rise in serum AFP [8]. The differential diagnosis of retroperitoneal teratomas include ovarian tumours, renal cysts, adrenal tumours, retroperitoneal fibromas, sarcomas, haemangiomas, xanthogranulomas, enlarged lymph nodes and perirenal abscesses [3, 9]. Scholz et al suggested that a high percentage of extragonadal germ cell tumours have signs of burned out or active tumour in the testis. However, it was not so in our case [15].
Plain abdominal radiograph always shows a soft tissue mass. Calcifications appear in 53–62% of teratoma cases and are useful for the pre-operative diagnosis. It may be within the tumour or on the rim of the cyst wall [2, 3, 7]. Even though 74% of benign teratomas contain calcification, they also occur in 25% of malignant teratomas.
Ultrasound can identify the cystic, solid or complex components of the tumour. The acoustic shadow induced by calcification in the teratoma, and occasionally fat-fluid levels, are described [10]. The cystic portion may contain sebum, non-fat fluid and structures resembling fetal parts. Fluid may fill the dependent portion of the tumour producing a fat–fluid interface with the sebum. Ultrasound does not permit definite differentiation among the fat, other forms of soft tissue and calcific deposits [10].
CT gives more specific information on the fat, proteinaceous fluid and calcification using the Hounsfield values determination. The presence of fatty portions of the tumour in the horizontal interface with dependant fluid, which probably represents sebum, is virtually pathognomon of a teratoma [8, 10]. CT is better than ultrasound at defining the teratomas extent to the surrounding organs and in evaluating the cyst wall [10].
MRI with coronal and sagittal scans are superior to ultrasound and CT for demonstrating the anatomical relationship with adjacent organs such as abdominal aorta or spinal cord and local tumour spread [11, 12].
In addition, MRI is unable to show calcification, but it can distinguish fluid, fat, calcium and soft tissue elements, and predict resectability and evaluate recurrence [13].
Angiography can detect the blood supply and the presence of hypervascularity, arterial encasement and organ invasion, often suggesting malignancy [14]. Macroscopically, teratomas can be divided into either cystic or solid. Cystic teratomas are mostly benign, containing sebaceous materials and mature tissue types. On the other hand, solid teratomas are usually malignant and composed of immature embryonic tissues in addition to adipose, cartilaginous, fibrous and bony components [7].
The prognosis is excellent for benign retroperitoneal teratoma if complete resection can be accomplished [3]. Conversely, malignant teratoma usually recurs despite surgical intervention, with a median survival of 18 months [7].
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Conclusion
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Primary retroperitoneal (RP) teratoma is a rare entity, which has a distinctive imaging appearance. We describe herein the rare case of a 22-year-old male in whom a retroperitoneal teratoma was found to have classical imaging morphology by ultrasound and CT. The tumour was resected and histopathological examination confirmed the diagnosis of primary benign retroperitoneal teratoma.
Received for publication July 15, 2005.
Revision received October 11, 2005.
Accepted for publication October 13, 2005.
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References
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Abstract
Introduction
