Miserable 9 Years of Life: a Misdiagnosed and Mismanaged Case of Large Retroperitoneal Teratoma

Introduction

Germ cell tumors (GCTs) predominantly occur in the gonads, and the most frequent extragonadal site remains the sacrococcygeal region while the retroperitoneum is rare. Primary retroperitoneal GCTs account for less than 4% of all GCTs and up to 11% of all retroperitoneal neoplasms [1]. Rarely neural tissue can be present in GCT because of which biopsies can be mistakenly reported as neuroblastoma, which is the most common pediatric retroperitoneal tumor. Both these tumors have radiological heterogeneity, and calcifications are common in both. However, the treatment of GCT and neuroblastoma is vastly different, and making an accurate diagnosis is paramount before initiating any form of therapy.

Case Report

A 4-month-old male child was evaluated elsewhere for gradual abdominal distension. A computerized tomography (CT) scan revealed a retroperitoneal mass, which was biopsied. The histology was reported as poorly differentiated neuroblastoma at two tertiary care centers. Bone marrow evaluation was negative for involvement. The child received carboplatin and etoposide as 1st-line chemotherapy for 4 cycles. Since the reassessment scan did not report any regression, the chemotherapy was supplemented with vincristine and cyclophosphamide. Despite this, the mass remained unchanged and was deemed unresectable; hence, whole abdominal radiotherapy was administered without relief. The child subsequently went on receiving non-allopathic therapies for 6 years without benefit. Distension progressed gradually, and percutaneous drainage of the cystic component was done on multiple occasions with temporary benefit. At the age of 9 years, the child presented to us with massive abdominal distension, a discharging sinus draining malodorous fluid. The child was nutritionally depleted, and the mass occupied all of the abdomen and pelvis (Fig. 1). Previous biopsy tissues were unavailable for review. Considering NB as a working diagnosis, an FDG–PET (18-fluorodeoxyglucose–positron emission tomography) CT was performed that revealed a 25 × 18 × 19 cm mass with solid and cystic components with areas of fat density and calcifications. It was displacing all major abdominal viscera without infiltration (Fig. 2). The infrahepatic inferior vena cava (IVC) was not visualized, and the right kidney was displaced superiorly with hydronephrosis, thinned cortical parenchyma, and delayed contrast uptake and excretion. There was low-grade, non-uniform FDG avidity with an SUV (standardized uptake value) maximum of 4.2. Serum ferritin and lactate dehydrogenase were normal.

Fig. 1.

Clinical picture showing gross abdominal distension, discharging sinus, and dilated vein

Fig. 2.

Axial and coronal computed tomography images showing a large predominantly cystic and solid mass with chunky calcification and areas of fat density within. The right kidney is grossly hydronephrotic (arrows) and pushed up by the tumor. The mass almost fills the abdominal cavity with the displacement of the bowels and the major vessel to the left

The patient was discussed in the multidisciplinary clinic and based on radiological findings; a diagnosis of primary retroperitoneal teratoma was made. The child was nutritionally optimized and was taken up for surgery. Intraoperatively, a 25-cm thin-walled, solid cystic mass displaced all intraperitoneal structures to the left. The right kidney and ureter were inseparable from the mass. IVC was thinned out and draped over the mass without an identifiable plane for dissection. Multiple collaterals replaced the infrarenal IVC. Posteriorly, the mass was densely adherent to the psoas and the right diaphragmatic crus. Excision of the mass with en bloc nephrectomy, infrarenal caval resection without reconstruction, limited diaphragmatic and psoas muscle resection, and in continuity removal of the sinus tract was performed (Fig. 3). The surgical duration was 5 h with 150 ml of blood loss. The patient endured an uneventful recovery and was discharged on postoperative day 5. The histopathology revealed mature teratoma containing bone, cartilaginous, and glial tissues. No adjuvant therapy was offered, and the child remains disease-free in 4-month follow-up.

Fig. 3.

Intraoperative pictures showing the left renal vein (small white arrow) and suprarenal inferior vena cava (arrowhead) plastered over the mass. The infrarenal inferior vena cava is replaced by a small-caliber vein. The ligated stump of the right renal vein and infrarenal inferior vena cava is shown by the long white arrow

Discussion

The differential diagnosis of large cystic abdominal masses in children is extensive. They can mimic a pancreatic congenital cyst, pseudocyst, multicystic dysplastic kidney, neuroblastoma, large Wilms’ tumor, mesenteric cyst, or a lymphangioma. Teratoma displays no pathognomonic signs or symptoms, and their clinical manifestation depends largely on their size and location. The diagnosis of a retroperitoneal lesion is usually made on imaging. CT can identify and quantitatively assess various components like soft-tissue density, fat, and sebaceous content based on the Hounsfield unit. Retroperitoneal GCTs are typically large at presentation. Encasement, displacement, and compression of abdominal vessels are common [1, 2]. A combination of calcification, fat, fluid, and soft tissue in a mass is diagnostic of teratoma, and calcifications are seen in 80–90% of cases [2]. Pressure on adjacent bones may cause vertebral bodies or pedicle thinning. Neuroblastoma instead tends to encase vessels and may have an invasion of adjacent organs [3]. But both these tumors are heterogeneous with calcifications and can be difficult to differentiate at times.

Immature teratomas contain at least the foci of embryonal structures or incompletely differentiated tissues. The occurrence of neural tissues in benign mature cystic teratoma is well known [4, 5]. Most frequently primitive neuroectodermal tissue is detected and consists of primitive neurotubuli, rosette-like structures, and even neuroblastomatous foci because of which they can mimic neuroblastoma on pathology. The report of Marcial-Rojas and Medina showed 22–47% peripheral nerves, 25–41% brain tissues, 19–25% ependymal cells, and 19–22% ganglionic cells in mature cystic teratoma [4]. In general, the degree of immaturity correlates with mitotic activity and proliferation rate assessed by Ki67 immunostaining [6]. Somatic-type malignancies develop in 3 to 6% of GCT with teratomatous differentiation [7, 8]. Exclusively, there are case reports of NB arising from GCTs. Unal et al. reported a case of neuroblastoma arising from an unresected sacrococcygeal teratoma in a 6-year-old girl [9]. In another study, Niwa et al. reported 2 cases of ovarian neuroblastoma arising from mature cystic teratomas of the ovary [10].

In this particular case, the patient attended a hospital at the age of 4 months. If an accurate diagnosis was established, it could have been probably resected without a nephrectomy and avoiding the morbidity of futile treatments and that of an expanding abdominal tumor for 9 years. To the best of our literature search, there are no pediatric cases where teratoma was misdiagnosed for neuroblastoma in the abdomen. Teratomas have been reportedly confused with other pathologies. Chuan Li et al. reported a case of intrapulmonary teratoma, which was initially treated as intrapulmonary aspergilloma based on CT thorax findings which showed fungal ball with air crescent sign and serum galactomannan assay [11]. Indistinguishably, Liu et al. published reports of 3 patients in which ruptured mediastinal teratoma was misdiagnosed as pneumonia and subsequently as tuberculosis and treated for the same. When symptoms did not improve, surgical resection was performed which revealed mature teratoma [12]. Yoshida et al. reported a middle-aged female with greater omentum mass treated as an ovarian cyst that turned out to be a mature cystic teratoma on pathology [13].

The significant theme is that when the primary line of treatment for a suspected pathology does not reap benefits, the diagnosis should be strongly questioned. Review of the case in multidisciplinary meets, revisiting the clinical details, imaging, and pathology should be done. Skepticism on chemotherapy responsive tumors should be placed when chemotherapy fails. Surgical excision should be considered early for such lesions even if the working diagnosis is neuroblastoma. Expert surgical reference should be sought in centers with experience in pediatric solid tumors as the majority of retroperitoneal GCTs are overwhelming with significant displacement of vessels and viscera [1].

Conclusion

Timely surgical intervention for all pediatric solid tumors is prudent since they are rare tumors with varied presentations. Multidisciplinary discussions prevent futile and prolonged treatment. Delay in diagnosis leads to increased morbidity from ineffective treatment and consequent extensive surgery. Chemotherapy-sensitive tumors should be questioned when first-line chemotherapeutics agents fail. Many of the deemed inoperable tumors can be resected at a high volume surgical center; thus, opinion should be sought before consideration of non-surgical options.

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All data and material are available within the manuscript.

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The authors declare that they have no conflict of interest.

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