Mature cystic teratoma of the retroperitoneum

Case contributed by Dr Jan Frank Gerstenmaier


This otherwise healthy patient presented with abdominal fullness which developed during his twenties.

Patient Data

Age: 29
Gender: Male

CT organized by GP


There is an extremely large mass with various densities including fat located in the abdomen and pelvis to the right, possibly within the retroperitoneum. The right kidney is displaced across the midline.

Heterogeneous mass with mixed echogenicity and fat corresponding to the abnormality seen on CT. No internal color doppler signal.

The patient underwent elective resection of the mass

Gross pathological specimens


CLINICAL NOTES: R retroperitoneal tumor resection. ?Teratoma. MACROSCOPIC DESCRIPTION: "Retroperitoneal tumor": The specimen is a grey fluctuant cystic mass, 7753g and 335x270x60mm with adrenal gland 60x25x10mm stretched over the surface. A separate rounded mass 20x15x10mm and loose tissue 35x20x10mm are also present in the container. The main mass has two locules 170x100mm and 280x200mm containing sebaceous material and hair. The cyst content is photographed and discarded. The cyst wall ranges from 2-10mm in width. The separate mass is also cystic, with locules ranging from 2-10mm in maximum dimension. BLOCK DESIGNATION: A - rounded mass. B-E,G - main cystic mass, with thicker areas of wall. F - loose tissue. H - adrenal. I,K,L - rounded mass J,M-R - main cystic mass, with remaining thicker areas of wall. S,T - loose tissue. P17. (GS) 



MICROSCOPIC DESCRIPTION: The locules of the main mass are lined partly by skin-like tissue with epidermis and skin adnexae, but there are areas with hollow viscus-like structures composed of various types of mature glandular epithelium, including respiratory epithelium, small bowel epithelium and cuboidal epithelium, with adjacent layers of smooth muscle. There is also mature neural tissue including nerve bundles and ganglion cells, mature adipose tissue and clustered blood vessels. The thicker parts of the cyst wall and the separate rounded fragment contain spaces lined by glandular epithelium and surrounded by smooth muscle. A few lymphoid aggregates are present. Immature elements are not seen. The adrenal gland is normal and the loose tissue is congested but otherwise unremarkable soft tissue. COMMENT: Primary retroperitoneal teratomas are rare (Gatcombe et al, J Surg Oncol 2004;86:1007-113) and metastasis from a testicular primary should be excluded clinically. Although no immature or malignant component has been identified, mature teratomas in adult males may not be completely benign. As the lesion was received in at least two pieces, completeness of excision cannot be assessed. DIAGNOSIS: Retroperitoneal tumor: Mature cystic teratoma.

Case Discussion

On cutting the resected tumor, literally buckets full of sebaceous material emerged. Unusual about this case is the off midline location and the occurrence in a male. The CT appearances are diagnostic.

Gross pathology and histology images credits: Dr Gabriel Scripcaru, Pathology Registrar at Royal Melbourne Hospital

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