Indian Journal of Pathology and Microbiology

: 2015  |  Volume : 58  |  Issue : 1  |  Page : 124--125

Sacrococcygeal teratoma with ectopic immature renal tissue

Shatavisha DasGupta, Ranajoy Ghosh, Ram Narayan Das, Uttara Chatterjee 
 Department of Pathology, Institute of Post Graduate Medical Education and Research, Kolkata, West Bengal, India

Correspondence Address:
Dr. Shatavisha DasGupta
15A/7, East Road, Santoshpur, Kolkata - 700 075, West Bengal

How to cite this article:
DasGupta S, Ghosh R, Das RN, Chatterjee U. Sacrococcygeal teratoma with ectopic immature renal tissue.Indian J Pathol Microbiol 2015;58:124-125

How to cite this URL:
DasGupta S, Ghosh R, Das RN, Chatterjee U. Sacrococcygeal teratoma with ectopic immature renal tissue. Indian J Pathol Microbiol [serial online] 2015 [cited 2021 Apr 15 ];58:124-125
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The occurrence of renal tissue in sacrococcygreal teratomas has rarely been reported in the literature. Sacrococcygeal teratoma is a rare childhood tumor with an incidence of one in 35,000-40,000 births. Extra-renal presence of structures consistent with ectopic immature renal tissues (EIRTs) have rarely been reported, both in teratomas or unassociated with a teratoma. [1] A broad nomenclature has been used for these unusual findings: EIRT, mesonephric remnant tissue, hamartoma with primitive renal tissue, extrarenal nephrogenic rests, extrarenal nephrogenic blastema, heterotopic nephrogenic rests, ectopic nephrogenic rests and extrarenal nephroblastomatosis. [2],[3] From a histological standpoint, EIRTs are generally described as aggregates of blastemal tissues, tubules and occasional glomeruli with a variable amount of admixed fibrous stroma.

A full term baby girl, born at 38 weeks of gestation, was noted to have a lump at the base of the spine. She presented to the outpatient department at 9 months of age. Her ultrasound scans and magnetic resonance imaging showed a large sacrococcygeal mass with an intrapelvic component showing solid and cystic areas. The mass was removed along with the coccyx. The alpha-fetoprotein (AFP) values were marginally raised, and human chorionic gonadotrophin values were within normal limits. Grossly, the mass measured 10 cm across with solid and cystic areas. Microscopic examination showed the presence of varying admixture of tissues. There was skin with appendages, glial tissue, bone, cartilage along with colonic and respiratory epithelium. In addition, immature neural tissue was noted with presence of neuroblastic foci [[Figure 1]a and b]. In focal areas, there was the presence of renal tissue in the form of immature glomeruli, tubules and blastemal components [[Figure 1]c and d]. A diagnosis of immature teratoma with the rare finding of the renal differentiation was made.{Figure 1}

Ectopic immature renal tissue probably represents metanephric remnants displaced during embryonic development. Its peculiar presence in the lumbosacral region, in cases of spinal dysraphism, supports the hypothesis that neural tube abnormalities may interfere with migration and morphogenesis of bystander renal tissue. [4],[5]

The strict similarity of ectopic immature renal structures to the foci of perilobar and intralobar nephrogenic rests/nephroblastomatosis occasionally found in neonatal kidneys and recognized potential source of nephroblastoma, could be a matter of concern and diagnostic uncertainty. [6] Generally, nephrogenic rests tend to form expanding, spherical nodules, surrounded by a fibrous pseudocapsule while EIRT usually consists of small multiple microscopic nests and islets. From a cytological point of view, only frank atypia is a reliable characteristic of nephroblastoma, since high mitotic rates and moderate pleomorphism are also found in EIRT. Therefore, if the immature renal tissue in a teratoma lacks obvious features of malignancy it should be considered as an "immature component," in analogy with the more common primitive neuroectodermal component of immature teratomas. In fact, it has been also proposed that areas reminiscent of nephroblastoma present in teratomas should be reported as nephroblastoma-like, when it involves half or more of a microscopic field seen with a ×4 objective, and as an immature component when smaller. [7] Glomerular differentiation can also pose a diagnostic problem with yolk sac tumor with Schiller-Duval bodies in cases of mixed germ cell tumours. Serum AFP levels and staining for AFP can be useful in such cases, however, bearing in mind small elevations, which can be associated with the presence of gut or respiratory epithelium in teratomas.

Ectopic immature renal tissue, without an associated teratoma in the pediatric age group does not usually have a sinister prognosis. A diligent follow-up protocol seems to be adequate for their management. However, immature renal tissue, when encountered within a teratoma necessitates a closer attention. Presence of atypia or other features of malignancy portends the possibility of a nephroblastoma, whereas if such features are lacking, EIRT should be considered likewise to any other immature embryonal-type components.


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