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     Journal of Indian Association of Pediatric Surgeons
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Year : 2023  |  Volume : 28  |  Issue : 6  |  Page : 541-543

A rare case of extragonadal mixed germ cell tumor of the Sacrococcygeal Region with mature thymic tissue in the teratoma component

1 Department of Pathology, Maulana Azad Medical College and Associated Hospitals, New Delhi, India
2 Department of Pediatric Surgery, Maulana Azad Medical College and Associated Hospitals, New Delhi, India

Date of Submission10-Jul-2023
Date of Decision10-Aug-2023
Date of Acceptance10-Aug-2023
Date of Web Publication06-Oct-2023

Correspondence Address:
Reena Tomar
Room 54, Department of Pathology, Pathology Block, Maulana Azad Medical College, Bahadur Shah Zafar Marg, New Delhi - 110 002
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jiaps.jiaps_150_23

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A rare extragonadal mixed germ cell tumor of the sacrococcygeal area presenting with mature thymic tissue in the teratomatous component, a rare finding and the first reported case of such an association.

Keywords: Extragonadal germ cell tumor, sacrococcygeal, thymic tissue in teratoma

How to cite this article:
Chaturvedi A, Tomar R, Balhara K, Khurana N, Ratan SK, Mitra A. A rare case of extragonadal mixed germ cell tumor of the Sacrococcygeal Region with mature thymic tissue in the teratoma component. J Indian Assoc Pediatr Surg 2023;28:541-3

How to cite this URL:
Chaturvedi A, Tomar R, Balhara K, Khurana N, Ratan SK, Mitra A. A rare case of extragonadal mixed germ cell tumor of the Sacrococcygeal Region with mature thymic tissue in the teratoma component. J Indian Assoc Pediatr Surg [serial online] 2023 [cited 2023 Nov 28];28:541-3. Available from: https://www.jiaps.com/text.asp?2023/28/6/541/387397

   Introduction Top

Germ cell tumors (GCTs) are heterogeneous tumors arising from primordial germ cells, encompassing both benign and malignant entities. Whenever they are extragonadal, they can be found in various midline locations.[1] Mixed GCTs are uncommon and account for 8% of all malignant GCTs, including two or more types of malignant, primitive, or germ cell components. The combination of yolk sac tumor and dysgerminoma is the most prevalent subtype.[2]

   Case Report Top

The Outpatient Department of this institute received a visit from a 5-year-old girl who had a sacral mass that had been present since birth, starting out as an olive-sized mass and gradually growing to its current size. Only two weeks before the hospital visit, the sacral mass had been accompanied by pain.

Clinical examination of the sacrococcygeal region revealed swelling of size 11 cm ×10 cm ×6 cm, 5 cm away from the posterior superior iliac spine and 3 cm away from the coccyx. Externally, the swelling was nodular with overlying dilated veins, and no ulceration/discoloration was present. The anal opening was caudally displaced. The swelling was firm to hard in consistency and tender and had restricted mobility. The patient did not have any complaints regarding feeding, defecation, and urination.

The preoperative alpha-fetoprotein (AFP) level was >500 ng/mL, and beta-human chorionic gonadotropin (HCG) levels were within the normal range. Magnetic resonance imaging (MRI) showed a large well-defined heterogeneous mass at the midline of the lower coccygeal region measuring 10 cm ×7.5 cm. No metastatic disease was noted. A primary clinical diagnosis of sacrococcygeal teratoma, Altman Type III, was made.

A tiny core needle biopsy from the mass was sent for histopathological examination. Microscopic examination, of the very tiny tru-cut biopsy from the swelling, showed features of only a yolk sac tumor, having sheets of polygonal cells with large vesicular nuclei with prominent nucleoli, brisk mitosis, and clear-to-eosinophilic cytoplasm. These cells were positive for AFP on immunohistochemistry.

Surgical excision was planned after four cycles of chemotherapy – bleomycin, etoposide, and cisplatin (BEP) regimen. Post four cycles of chemotherapy, the AFP level dropped drastically to 2 ng/mL; however, not much change was noted in the size of the mass.

The mass was surgically completely excised and sent for histopathological examination. Grossly, the specimen received was a gray-brown, globular, solid-cystic soft-tissue mass measuring 9 cm ×7.5 cm ×6 cm. On cutting open, it revealed solid areas measuring 6 cm ×6 cm ×4.5 cm and grossly showed the presence of hair follicles and cartilage. The cyst contained pultaceous material. The wall thickness of the cyst varied from 0.1 to 0.3 cm. Microscopic examination of multiple sections from the specimen showed the presence of mature cartilage, fibrocollagenous and fibroadipose tissue, skeletal muscles, vessels, stratified squamous epithelium, and mature nerve fibers [Figure 1] along with the rare presence of mature thymic tissue (ectopic) with Hassall's corpuscles [Figure 2]. There was a presence of necrosis and a small focus of malignancy was identified, indicating a near-total response to chemotherapy of the yolk sac tumor component.
Figure 1: (a) Cartilage. (b) Skin (inset - muscle, adipose tissue). (c) Nerve. (d) Immature tumor remnant; (H and E, ×400)

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Figure 2: (a) Tumor cells (H and E, ×100). (b) Alpha-fetoprotein-positive tumor cells. (c) Mature thymic tissue (H and E, ×40). (d) Hassall's corpuscle (H and E, ×400)

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Hence, a diagnosis of mixed GCT (>90% teratoma, <10% yolk sac tumor) was made. The postoperative course was uneventful. The patient was followed up clinically and radiologically, every 3 months for the 1st year, and biannually after that for 3 years. The latest MRI, done at 3-month follow-up, reported no obvious residual or recurrent mass.

   Discussion Top

Primary extragonadal GCTs are rare, and the actual incidence of this form of cancer is unclear. It is believed that they account for 3%–5% of all GCTs.[1] Mixed GCTs are uncommon and consist of at least two malignant GCT components.

The clinical course is unpredictable, and there is a chance of significant metastases and aggressive behavior.[2] Regular imaging is frequently used to detect sacrococcygeal germ cell tumors in utero, and if they are large enough, they may impede labor or induce hydrops fetalis. It typically presents as an external, palpable lump in newborns, but it can result in severe morbidity; therefore, any midline tumor should be examined to rule out a diagnosis of a germ cell tumor. The current case presented with lower back swelling and pain.

The serum AFP level, morphology, and immunohistochemistry staining are all needed to strongly suggest the diagnosis of mixed GCT.

Depending on the components of the tumor, mixed GCTs produce AFP and beta-HCG. AFP of the current case was elevated (>500), while beta-HCG was normal. A biopsy is necessary for a definite diagnosis and treatment of extragonadal GCTs.

Teratoma is the most common benign histology of sacrococcygeal GCTs accounting for 32%–66%,[3] and the most common malignant histology is the yolk sac tumor, which is frequently admixed with teratoma,[2] as was present in our case.

The treatment of mixed GCTs concentrates on the most malignant components. Complete surgical excision is the primary therapy for children with endodermal sinus tumors with adjuvant chemotherapy,[2] as was done in the current case. If tumor biomarkers return to normal, but there is a residual lump larger than 1 cm, surgery should be undertaken as in the current case.

Mixed GCTs, which mostly consist of teratomas with other malignant components (other GCTs, carcinomas, or sarcomas), have been observed to be more aggressive. Many of the relapses occur within a year after the diagnosis. Thus, a careful follow-up with serial AFP-level monitoring should be performed for at least 2 years.[2]

The occurrence of ectopic tissues in sacrococcygeal teratomas has been reported in various published case reports, but the occurrence of mature thymic tissue is the first such reported case. Ectopic brain tissue and immature renal tissue are two notable ectopic tissues in pediatric teratomas.[4] An instance of adrenal gland heterotopic tissue in the same region has also been documented.[5] A more thorough literature search reveals a case of immature teratoma in the lumbosacral area made up of immature Wilms' tumor and mature teratomatous components.[6] A mature teratoma with a rudimentary heart has been documented, but ectopic mature thymic tissue was only recorded in a case of ovarian teratoma.[6]

In conclusion, the occurrence of primary mixed GCT in the sacrococcygeal region is a rare condition. Proper initial surgery with proper staging biopsies, followed by combination chemotherapy, can significantly improve these patients' prognosis. A thorough review of the literature published already reveals that this is the first such case of a mature teratoma with ectopic mature thymic tissue, which is an incredibly rare occurrence.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

   References Top

Chen SH, Du CJ, Lai JY, Chang TY, Yang CP, Hung IJ, et al. Malignant sacrococcygeal germ cell tumors in children in Taiwan: A retrospective single-center case series. Medicine (Baltimore) 2021;100:e24323.  Back to cited text no. 1
Sabr WN, Kakamad FH, Salih AM, Salih RQ, Salih KM, Abdullah BA, et al. Mixed germ cell tumor of sacrococcygeal region; A case report with literature review. Ann Med Surg (Lond) 2022;74:103247.  Back to cited text no. 2
Nasreen S, Rahman M, Mosarrat S, Sharmin T, Rahman M. Malignant sacrococcygeal teratoma with yolk sac differentiation in a child – A case presentation. Open J Pathol 2018;8:60-7.  Back to cited text no. 3
Coli A, Angrisani B, Chiarello G, Massimi L, Novello M, Lauriola L. Ectopic immature renal tissue: Clues for diagnosis and management. Int J Clin Exp Pathol 2012;5:977-81.  Back to cited text no. 4
Mandal B, Chatterjee G, Bhattacharya K, Roy D, Das RN, Chatterjee U. Sacrococcygeal teratoma with complete adrenal gland. J Cancer Res Ther 2015;11:1040.  Back to cited text no. 5
Sharma MC, Jain D, Sarkar C, Bhatnagar V, Rishi A, Suri V, et al. Lumbosacral Wilms' tumor as a component of immature teratoma associated with spinal dysraphism – A rare case and short literature review. Fetal Pediatr Pathol 2009;28:201-8.  Back to cited text no. 6


  [Figure 1], [Figure 2]


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